Hydrogenated multi-block linear styrene-butadiene copolymers, process for their preparation and use as viscosity index improver additives

Abstract

Hydrogenated multiblock linear styrene-butadiene copolymers having the general formula (I) or (II): (EB)1-S1-(EB)3-S2-(EB)2 (I), (EB)1-S1-(EB)2 (II) Wherein: - (EB)1, (EB)2 and (EB)3 represent hydrogenated polymer blocks derived from 1,3-butadiene; - S1 and S2 represent polymer blocks derived from styrene; wherein: - In general formula (I), the amount of polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 56% to 74% by weight, preferably 64% to 70% by weight, relative to the total weight of the copolymer, said amount being defined as the sum of [(EB)1 + (EB)2], the amount of polymer block (EB)3 derived from 1,3-butadiene is 1% to 4% by weight, preferably 1% to 2% by weight, relative to the total weight of the copolymer, and the amount of polymer blocks S1 and S2 derived from styrene is 25% to 40% by weight, preferably 29% to 34% by weight, relative to the total weight of the copolymer, said amount being defined as the sum of S1 + S2; - In general formula (I), the amount of polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 56% to 74% by weight, preferably 64% to 70% by weight, relative to the total weight of the copolymer, said amount being defined as the sum of S1 + S2; - In general formula (I), the amount of polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 1% to 4% by weight, preferably 1% to 2% by weight, relative to the total weight of the copolymer, said amount being defined as the sum of S1 + S2; - In general formula (I), the amount of polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 25% to 40% by weight, preferably 29% to 34% by weight, relative to the total weight of the copolymer, said amount being defined as the sum of S1 + S2; - In general formula (I), the amount of polymer blocks (EB)1 In formula (II), the amount of polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 60% to 75% by weight, preferably 66% to 71% by weight, relative to the total weight of the copolymer, the amount being defined as the sum of [(EB)1 + (EB)2], and the amount of polymer block S1 derived from styrene is 25% to 40% by weight, preferably 29% to 34% by weight, relative to the total weight of the copolymer; - in the polymer blocks (EB)1, (EB)2 and (EB)3 derived from 1,3-butadiene, the content of polybutadiene units having configurations 1,2 is 45% to 70% by weight, preferably 50% to 65% by weight, relative to the total weight of the butadiene units, and the content of units having configurations 1,4 is 30% to 55% by weight, preferably 35% to 50% by weight, relative to the total weight of the butadiene units. The aforementioned hydrogenated multiblock linear styrene-butadiene copolymer can be advantageously used as a viscosity index improver (VII) additive for lubricating oil compositions, such as those for diesel and gasoline passenger cars or heavy-duty diesel engines, as well as functional fluids, such as manual or automatic transmission fluids and hydraulic fluids.

Description

[0001] This invention relates to hydrogenated multiblock linear styrene-butadiene copolymers.

[0002] More specifically, the present invention relates to hydrogenated multiblock linear styrene-butadiene copolymers having a specific multiblock structure (i.e., having a specific general formula (I) or (II) reported below).

[0003] The aforementioned hydrogenated multiblock linear styrene-butadiene copolymer can be advantageously used as a viscosity index improver (VII) additive for lubricating oil compositions, such as those for diesel and gasoline passenger cars or heavy-duty diesel engines, as well as functional fluids (e.g., manual or automatic transmission fluids and hydraulic fluids).

[0004] The present invention also relates to a method for preparing the hydrogenated multiblock linear styrene-butadiene copolymer.

[0005] The present invention also relates to a concentrated solution comprising at least one of the above-mentioned hydrogenated multiblock linear styrene-butadiene copolymers in at least one lubricating base oil, wherein the lubricating base oil is selected from mineral-derived, synthetic-derived, animal-derived, plant-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-described hydrogenated multiblock linear styrene-butadiene copolymers (as is or in a concentrated solution) and at least one lubricating base oil selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof.

[0007] As is well known, the viscosity of lubricating oil changes with temperature. Many lubricating oils must be used over a wide temperature range, so it is important that the lubricating oil is not too viscous at low temperatures and does not flow too much at high temperatures. The change in lubricating oil viscosity with temperature is expressed by a viscosity index value: the higher the viscosity index value, the lower the change in lubricating oil viscosity with temperature.

[0008] It is also known that polymer-based additives are used as viscosity index improvers (VII) of lubricating oils to adjust the viscosity of the lubricating oil as temperature changes, i.e., increasing the viscosity at high temperatures and limiting the increase in viscosity at low temperatures as much as possible.

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

[0010] For example, the following US patents describe the synthesis of hydrogenated linear polymers of conjugated dienes and conjugated styrene-diene copolymers in lubricant compositions and their use in lubricants: US 3,554,911 (hydrogenated atactic butadiene-styrene copolymer); US 3,668,125 (hydrogenated or saturated block copolymers having at least three blocks, e.g., hydrogenated polystyrene-polybutadiene, hydrogenated polystyrene-polyisoprene); US 3,772,196 (biblock 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 (hydrogenated “conical” isoprene-styrene copolymer); US 3,835,053 (hydrogenated polyisoprene homopolymer); EP 585269 [hydrogenated butadiene-diene copolymers, for example, hydrogenated butadiene-isoprene copolymers, possibly having a star-shaped structure] and EP 578725 (hydrogenated polybutadiene block copolymers comprising 1,4-butadiene monomer units and 1,2-butadiene monomer units).

[0011] US Patent 9,133,413 relates to polymers suitable for use as viscosity index improvers in lubricating oil compositions, comprising:

[0012] - A linear polymer, characterized by the formula:

[0013] D'-PA-D''; and

[0014] - Star-shaped polymer, characterized by the formula:

[0015] (D'-PA-D'' )n -X;

[0016] Wherein D' represents a block derived from at least one diene selected from isoprene and butadiene; PA represents a block derived from styrene; D'' represents a block derived from at least one diene selected from isoprene and butadiene; n is 10 to 20 and represents the average number of arms per star polymer; and X represents the polyolefin coupling agent core.

[0017] At least one of the diene blocks D' and D'" is a copolymer block derived from a mixture of diene monomers, wherein about 72% to about 85% by weight of the incorporated monomer units are derived from isoprene, and about 15% to about 28% by weight of the incorporated monomer units are derived from butadiene, and wherein at least about 80% by weight of the butadiene is incorporated in a 1,4 configuration; and

[0018] The number-average molecular weight of D' is about 20,000 to about 60,000 Daltons; the number-average molecular weight of PA is about 10,000 to about 35,000 Daltons; and the number-average molecular weight of D” is about 5,000 to about 30,000 Daltons. The polymers described above are claimed to be suitable as viscosity index improvers for lubricating oil compositions, including lubricating oil compositions for passenger cars and heavy-duty diesel engines as well as marine diesel engines, and functional fluids (e.g., automatic transmission fluids).

[0019] US patent application US 2021 / 0171853 relates to viscosity modifier (VM) concentrates, which comprise:

[0020] - Approximately 60 to approximately 95 parts of diluted oil; and

[0021] - About 5 parts to about 40 parts of a linear triblock copolymer, characterized by the formula:

[0022] D'-PA-D'';

[0023] Wherein D' represents a diene-derived block, PA represents a block derived from a monoalkenyl aromatic hydrocarbon, D” represents a diene-derived block, and the linear triblock copolymer is present in an effective amount for altering the kinematic lubricating viscosity (KV100) of the concentrate at approximately 100°C.

[0024] The concentrate contains at least 50% by weight of diluent oil, and the effective amount of the linear triblock copolymer results in the concentrate containing at least 6% by weight of the linear triblock copolymer.

[0025] The diluent oil has a KV100 of about 2 cSt to about 40 cSt, the concentrate has a KV100 of about 2000 cSt or less, and the concentrate has a beaker pour of at least 87% and / or a tanδ of at least 1.8 at about 80°C. The linear triblock copolymer described above is claimed to be suitable as a viscosity modifier / viscosity index improver for lubricating oil compositions, including lubricating oil compositions and functional fluids (e.g., manual / automatic transmission fluids) for passenger cars, heavy-duty diesel engines, and marine diesel engines.

[0026] For each of the above-mentioned (co)polymers, the weight-average molecular weight (M) is... wThe increase in viscosity index (CPI) corresponds to an increase in thickening capacity (TP), thus reducing the amount of (co)polymer required to achieve a certain increase (thickening) in the viscosity index of the lubricating oil composition at high temperatures. For a (co)polymer 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, maintaining 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]. It is well known that, in contrast to thickening capacity (“TP”), the mechanical shear stability of a (co)polymer increases with its weight-average molecular weight (M). w The viscosity index decreases with increasing viscosity, therefore, the selection of viscosity index improver (“VII”) additives is usually based on the use of a large amount of mechanically shear-stabilized (co)polymers with low weight-average molecular weight (Mw) [i.e., low shear stability index (SSI) value] but low thickening ability (TP) and a small amount of polymers with high weight-average molecular weight (Mw). w A trade-off between (co)polymers with poor shear stability (i.e., high shear stability index (SSI) value) but high thickening capacity (TP).

[0027] It is also desirable to have (co)polymers that not only effectively improve the viscosity index of the lubricating composition (VII) and have good mechanical shear stability [i.e., a good shear stability index - SSI value], but also have dispersing properties for carbonaceous particles (“soot”) formed in the lubricating oil due to its operation in the engine. These carbonaceous particles (“soot”) formed due to oxidation processes in the lubricating oil are insoluble in the lubricating oil itself because they contain carbon particles with polar functional groups. These carbonaceous particles with polar functional groups tend to aggregate to form larger particles (agglomerates), which can precipitate to form deposits, primarily in the colder parts of the engine (e.g., the oil pan), where the lubricating oil resides for the longest time. Typically, to limit the formation of carbonaceous particle deposits (“soot”), dispersing additives (e.g., polyisobutylene succinimide (PIBSI)) are used, which coat the surface of the carbonaceous particles, thereby preventing them from agglomerating and precipitating.

[0028] Therefore, it would be highly advantageous for (co)polymers to also function as dispersants of carbonaceous particles (“fly ash”) and viscosity index improvers (VII) of lubricating oils, thereby enhancing the dispersibility of lubricating oils when necessary while reducing the amount of dispersing additives contained in the lubricating oil. It is also desirable that such (co)polymers be inexpensive and readily manufactured using industrially feasible methods.

[0029] Therefore, the problem faced by the applicant is to find an annual index improver (VII) copolymer for lubricating oils that, in addition to having good shear stability index (SSI) and thickening capacity (TP) values, can also be used as a dispersant for carbonaceous particles (“soot”) and, when used in concentrated solutions in lubricating base oils, can provide a clear and homogeneous solution even at low temperatures without forming gel-like compounds.

[0030] The applicant has now discovered a hydrogenated multiblock linear styrene-butadiene copolymer having a specific multiblock structure, namely having the specific general formula (I) or (II) reported below, which can be used as a viscosity index improver (VII) for lubricating oils. Besides having good shear stability index (SSI) and thickening capacity (TP) values, it can also be used as a dispersant for carbonaceous particles (“soot”) and, when used in concentrated solutions in lubricating base oils, provides a clear and homogeneous solution even at low temperatures without forming gel-like compounds. The aforementioned hydrogenated multiblock linear styrene-butadiene copolymer can be advantageously used as a viscosity index improver (VII) additive for lubricating oil compositions, such as those for diesel and gasoline passenger cars or heavy-duty diesel engines, as well as functional fluids (e.g., manual or automatic transmission fluids and hydraulic fluids). Furthermore, the aforementioned hydrogenated multiblock linear styrene-butadiene copolymer can be advantageously used as a dispersant for carbonaceous particles (“soot”) in lubricating oil compositions, such as those for diesel and gasoline passenger cars or heavy-duty diesel engines. Therefore, the aforementioned hydrogenated multiblock linear styrene-butadiene copolymer is particularly useful in the engine field, where proper lubrication is increasingly important for extending engine life (especially in diesel engines, and also in the latest direct-injection gasoline engines) and reducing fuel consumption: thus, proper lubrication has direct benefits for sustainability and reducing engine emissions.

[0031] Therefore, the subject of this invention is hydrogenated multiblock linear styrene-butadiene copolymers having general formula (I) or (II):

[0032] (EB)1-S1-(EB)3-S2-(EB)2 (I)

[0033] (EB)1-S1-(EB)2 (II)

[0034] in:

[0035] - (EB)1, (EB)2 and (EB)3 represent hydrogenated polymer blocks derived from 1,3-butadiene;

[0036] - S1 and S2 represent polymer blocks derived from styrene;

[0037] in:

[0038] - In general formula (I), the amount of polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 56% to 74% by weight, preferably 64% to 70% by weight, relative to the total weight of the copolymer, said amount is defined as the sum of [(EB)1 + (EB)2], the amount of polymer block (EB)3 derived from 1,3-butadiene is 1% to 4% by weight, preferably 1% to 2% by weight, relative to the total weight of the copolymer, and the amount of polymer blocks S1 and S2 derived from styrene is 25% to 40% by weight, preferably 29% to 34% by weight, relative to the total weight of the copolymer, said amount is defined as the sum of S1 + S2;

[0039] - In general formula (II), the amount of polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 60% to 75% by weight, preferably 66% to 71% by weight, relative to the total weight of the copolymer, said amount is defined as the sum of [(EB)1 + (EB)2], and the amount of polymer block S1 derived from styrene is 25% to 40% by weight, preferably 29% to 34% by weight, relative to the total weight of the copolymer;

[0040] - In the polymer blocks (EB)1, (EB)2 and (EB)3 derived from 1,3-butadiene, the content of polybutadiene units having configurations 1,2 is 45% to 70% by weight, preferably 50% to 65% by weight, relative to the total weight of butadiene units, and the content of units having configurations 1,4 is 30% to 55% by weight, preferably 35% to 50% by weight, relative to the total weight of butadiene units.

[0041] For the purposes of this specification and the foregoing claims, the definition of a numerical range always includes extreme values, unless otherwise stated.

[0042] For the purposes of this specification and the foregoing claims, the term "comprising" also includes the terms "consistently composed of" or "composed of".

[0043] For the purposes of this specification and the foregoing claims, the amounts of the polymeric blocks [(EB)1+(EB)2] derived from 1,3-butadiene and the amounts of the polymeric blocks (S1 or S1 + S2) derived from styrene (the amounts are expressed as a percentage by weight relative to the total weight of the copolymer) are as follows: 1 The method reported in the “H-NMR spectroscopy” section was used to determine the non-hydrogenated multiblock linear styrene-butadiene copolymer (“parent polymer”).

[0044] For the purposes of this specification and the foregoing claims, the amount of polymer block (EB)3 derived from 1,3-butadiene (the amount is expressed as a percentage of weight relative to the total weight of the copolymer) is theoretically determined relative to the amount of 1,3-butadiene fed into the polymer during the polymerization process in step (c) reported below.

[0045] For the purposes of this specification and the foregoing claims, the content of 1,2-configuration units and 1,4-configuration units in the polymer blocks derived from 1,3-butadiene (the content being expressed as a percentage by weight relative to the total weight of the butadiene units) shall be in accordance with the following " 1 The method reported in the “H-NMR spectroscopy” section was used to determine the unhydrogenated multiblock linear styrene-butadiene copolymer (“parent polymer”).

[0046] According to a preferred embodiment of the present invention, the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) has the following characteristics:

[0047] - The weight-average molecular weight (M) of each of the polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene w The average molecular weight (M) of each of the two polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 29,000 Da to 60,000 Da, preferably 30,000 Da to 48,000 Da. w If they are equal or different, they are preferred to be equal.

[0048] - Weight average molecular weight (M) of polymer block (EB)3 derived from 1,3-butadiene w The range is 900 Da to 6000 Da, preferably 1000 Da to 2800 Da;

[0049] - Weight-average molecular weight (M) of styrene-derived polymer blocks (S1 or S1+S2) w The range is 25,000 Da to 55,000 Da, preferably 26,000 Da to 48,000 Da;

[0050] - The degree of hydrogenation of the three polymer blocks (EB)1, (EB)2 and (EB)3 derived from 1,3-butadiene is greater than or equal to 98%, preferably greater than or equal to 99%, and more preferably equal to 100%;

[0051] - The weight-average molecular weight (M) of the hydrogenated multiblock linear styrene-butadiene copolymer w The range is 90,000 to 181,000 Daltons, with a preferred range of 113,000 to 147,000 Daltons.

[0052] - Corresponding to M w / M n The polydispersity index (PDI) of the ratio is 0.98 to 1.2, preferably 1.0 to 1.1.

[0053] For the purposes of this specification and the foregoing claims, the weight-average molecular weight (M) of each of the 1,3-butadiene polymer blocks (EB)1 and (EB)2 is... w The weight-average molecular weight (M) of styrene-derived polymer blocks (S1 or S1+S2) and polymer blocks derived from styrene. w The molecular weight of the unhydrogenated multiblock linear styrene-butadiene copolymer (“parent polymer”) was determined during polymerization according to the method reported in the “Determination of Molecular Weight” section below.

[0054] For the purposes of this specification and the foregoing claims, the weight-average molecular weight (M) of the polymer block (EB)3 derived from 1,3-butadiene is... w The amounts of 1,3-butadiene and lithium-based initiator fed into the polymerization process are theoretically determined.

[0055] According to a preferred embodiment of the present invention, the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) has the following characteristics:

[0056] - Shear stability index (SSI) of 3% to 20%, preferably 5% to 15%, measured in Group I base oils according to CEC-L-14-A-93 standard (30 shear cycles);

[0057] - Thickening capacity (TP) is 2.5 mm. 2 / s to 5 mm 2 / s, preferably 2.8 mm 2 / s to 4.5 mm 2 / s, measured in Group I base oils according to ASTM D445-21e2 standard;

[0058] - The cold viscosity at -25°C (“Cold Start Simulator Viscosity” - “CCS Viscosity”) is 5000 cP to 6800 cP, preferably 5500 cP to 6500 cP, measured in Group I base oils according to ASTM D5293-20 in the presence of additive MX 4333 (Eni SpA) (“Pour Point Depressant” - PPD);

[0059] - The cold viscosity at -20°C (“Cold Start Simulator Viscosity” - “CCS Viscosity”) is 2500 cP to 3400 cP, preferably 2700 cP to 3100 cP, measured in Group I base oils according to ASTM D5293-20 in the presence of additive MX 4333 (Eni SpA) (“Pour Point Depressant” - PPD);

[0060] - Pour point below -25°C, preferably -27°C to -45°C, measured in Group I base oils according to ASTM D5950-14 in the presence of additive MX 4333 (Eni SpA) (“pour point depressant” - PPD);

[0061] - The gel index is 3 to 10, preferably 5 to 8, and is measured in Group I base oils according to ASTM D5133-05 in the presence of additive MX 4333 (Eni SpA) (“pour point depressant” - PPD).

[0062] As described above, the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) can also be used as a dispersant for carbonaceous particles (“fly ash”) in lubricating oil compositions.

[0063] According to a preferred embodiment of the invention, the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) has the ability to disperse carbonaceous particles (“smoke”) in the lubricating oil composition, measured by a lacunarity value of 0 to 1, preferably 0.05 to 0.80.

[0064] The dispersibility is measured according to the method described and claimed in International Patent Application WO 2021 / 205360: further details are reported in the section “Determination of Dispersibility (Porosity) of Carbonaceous Particulate Matter (“Fly Ash”)” below.

[0065] As described above, the present invention also relates to a method for preparing the above-described hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II).

[0066] Therefore, another object of the present invention is a first batch method for preparing hydrogenated multiblock linear styrene-butadiene copolymers having the general formula (I):

[0067] (EB)1-S1-(EB)3-S2-(EB)2 (I)

[0068] Wherein (EB)1, (EB)2, (EB)3, S1, and S2 have the same meaning as reported above, and the method includes the following steps:

[0069] (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 to obtain block (EB)1.

[0070] (b) Add styrene to the polymer mixture obtained in step (a) and continue the living polymerization until the styrene is substantially completely converted, thereby obtaining blocks (EB)1-S1 and S2-(EB)2.

[0071] (c) Relative to the total weight of the butadiene-styrene copolymer obtained in step (b), 1,3-butadiene is added to the polymerization mixture obtained in step (b) in an amount equal to 2% by weight, preferably equal to 1% by weight, more preferably equal to 0.5% by weight, and the living polymerization is continued until the 1,3-butadiene is substantially completely converted. Subsequently, at least one coupling agent is added to the obtained polymerization mixture to obtain a multi-block linear styrene-butadiene copolymer (EB)1-S1-(EB)3-S2-(EB)2, wherein the blocks (EB)1 and (EB)2 are identical and the blocks S1 and S2 are identical.

[0072] (d) The multi-block linear styrene-butadiene copolymer obtained in step (c) is hydrogenated to obtain a hydrogenated multi-block linear styrene-butadiene copolymer having the general formula (I).

[0073] 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 filler monomers (i.e., 1,3-butadiene in steps (a) and (c) and styrene in step (b)) have been polymerized.

[0074] 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.

[0075] Typically, the amount of hydrocarbon solvent used in such copolymerization via an anionic pathway allows for complete dissolution of the monomers (i.e., 1,3-butadiene and styrene), any additives that may be present, 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 amount of hydrocarbon solvent used, relative to the total weight of the hydrocarbon solvent, results in a monomer concentration (i.e., 1,3-butadiene and styrene) in the hydrocarbon solvent of 4% to 20% by weight, more preferably 6% to 15% by weight.

[0076] According to a preferred embodiment of the invention, the at least one lithium-based initiator may be selected, for example, from compounds having the general formula (III):

[0077] R1(Li) n (III)

[0078] Where R1 represents C1-C of a straight chain or a branch chain. 20 (C2-C preferred) 12 ) alkyl, C3-C 30 (Preferred C4-C) 10 ) cycloalkyl, C6-C 30 (Preferred C6-C) 12 ) aryl, and n is an integer from 1 to 4.

[0079] 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.

[0080] The amount of lithium-based initiator that can be used in the method of the present invention depends on a variety of factors, such as the molecular weight of the monomer to be copolymerized and the copolymer to be obtained. Typically, the lithium-based initiator can be used in an amount of 0.01 phm to 0.25 phm (phm = parts per 100 parts by weight of monomer). Preferably, the amount of lithium-based initiator can be 0.01 phm to 0.15 phm, more preferably 0.012 phm to 0.01 phm.

[0081] 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 (dimethyl glime), dioxane, 2-methoxyethyl tetrahydrofuran (THFA-ethyl), 2-methoxyethyl tetrahydropyran or mixtures thereof; chelating amines, for example, N,N,N',N'-tetramethylethylenediamine (TMEDA); or mixtures thereof. Tetrahydrofuran (THF), 2-methoxy-ethyl-tetrahydrofuran (THFA-ethyl), or mixtures thereof are preferred.

[0082] The amount of polar modifier that can be used in the first method of the present invention depends on a variety of factors, such as the amount of lithium-based initiator used and the type of polar modifier used. For example, in the case of the first method described above for the purposes of the present invention, tetrahydrofuran (THF) can be used in an amount of 100 to 250 moles, preferably 140 to 190 moles, per mole of lithium-based initiator.

[0083] According to a preferred embodiment of the invention, the at least one coupling agent may be selected from, for example, dimethyldichlorosilane, diphenyldichlorosilane, methylphenyldichlorosilane, or mixtures thereof. Diphenyldichlorosilane is preferred. Preferably, the coupling agent and the lithium-based initiator may be used in a molar ratio of 0.4 to 0.6, more preferably 0.45 to 0.55.

[0084] According to a preferred embodiment of the present invention, in the first method:

[0085] - Step (a) can be performed at a temperature of 20°C to 100°C, preferably 25°C to 85°C; and / or for a duration of 10 minutes to 1 hour, preferably 20 minutes to 40 minutes; and / or

[0086] - Step (b) can be performed at a temperature of 40°C to 110°C, preferably 50°C to 95°C; and / or for a duration of 1 minute to 9 minutes, preferably 3 minutes to 7 minutes; and / or

[0087] - Step (c) can be performed at a temperature of 45°C to 115°C, preferably 55°C to 100°C; and / or for a duration of 3 to 30 minutes, preferably 4 to 25 minutes.

[0088] The hydrogenation step (d) described above can be carried out according to procedures known in the art. Preferably, it can be carried out in the presence of a titanium / magnesium-based catalytic composition (e.g., bis(cyclopentadienyl)titanium dichloride / butylethylmagnesium), as described, for example, in European patents EP 0816382 and EP 0914867.

[0089] Another object of the present invention is a second batch method for preparing hydrogenated multiblock linear styrene-butadiene copolymers having general formula (II):

[0090] (EB)1-S1-(EB)2 (II)

[0091] Wherein (EB)1, (EB)2, and S1 have the same meaning as reported above, and the method includes the following steps:

[0092] (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 to obtain block (EB)1.

[0093] (b') Add styrene to the polymerization mixture obtained in step (a') and continue the living polymerization until the styrene is substantially completely converted, thereby obtaining block (EB)1-S1;

[0094] (c') Add 1,3-butadiene to the polymerization mixture obtained in step (b') and continue the living polymerization until the 1,3-butadiene is substantially completely converted to obtain a linear multiblock styrene-butadiene copolymer (EB)1-S1-(EB)2, wherein the blocks (EB)1 and (EB)2 are the same as or different from each other.

[0095] (d') Add at least one terminating agent to the polymerization mixture obtained in step (c');

[0096] (e') The multi-block linear styrene-butadiene copolymer obtained in step (d') is hydrogenated to obtain a hydrogenated multi-block linear styrene-butadiene copolymer having the general formula (II).

[0097] The at least one hydrocarbon solvent, at least one lithium-based initiator, and at least one polar modifier may be selected from those reported above.

[0098] 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. Trimethyldichlorosilane 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.

[0099] According to a preferred embodiment of the present invention, in the second method:

[0100] - Step (a') can be performed at a temperature of 20°C to 60°C, preferably 25°C to 55°C; and / or for a duration of 10 minutes to 1 hour, preferably 20 minutes to 40 minutes; and / or

[0101] - Step (b') can be performed at a temperature of 30°C to 75°C, preferably 35°C to 70°C; and / or for a duration of 1 minute to 9 minutes, preferably 3 minutes to 7 minutes; and / or

[0102] - Step (c') can be performed at a temperature of 45°C to 115°C, preferably 45°C to 100°C; and / or for a duration of 10 minutes to 1 hour, preferably 20 minutes to 40 minutes; and / or

[0103] - The step (d') can be performed at a temperature of 45°C to 115°C, preferably 55°C to 110°C; and / or for a duration of 1 minute to 10 minutes, preferably 3 minutes to 8 minutes.

[0104] The hydrogenation step (e') described above can be carried out according to procedures known in the art as described above. Preferably, it can be carried out in the presence of a titanium / magnesium-based catalytic composition (e.g., bis(cyclopentadienyl)titanium dichloride / butylethylmagnesium), as described, for example, in European patents EP 0816382 and EP 0914867.

[0105] As reported above, the present invention also relates to a concentrated solution of at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) in at least one lubricating base oil, wherein the lubricating base oil is selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof.

[0106] Therefore, the present invention also relates to a concentrated solution comprising:

[0107] - Relative to the total weight of the concentrated solution, 3% to 30% by weight, preferably 5% to 25% by weight, more preferably 8% to 15% by weight of at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II).

[0108] - Relative to the total weight of the concentrated solution, 70% to 97% by weight, preferably 75% to 95% by weight, more preferably 85% to 92% by weight, of at least one lubricating base oil, said lubricating base oil being selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof.

[0109] It should be noted that the concentrated solution remains a clear, homogeneous solution even at cold temperatures (at least -5°C) and does not form a gel-like compound.

[0110] Mineral-derived lubricating base oils are derived from well-known petroleum refining processes, such as distillation, dewaxing, deasphalting, dearomatization, and hydrogenation.

[0111] The synthetically sourced lubricating base oil may preferably be selected from: hydrocarbon oils, such as polymerized and hydrogenated terminal or internal olefins; alkylbenzenes; polyphenyls; alkylated diphenyl ethers; polyalkylene glycols and their derivatives, wherein the terminal hydroxyl groups have been modified, for example, by esterification or etherification.

[0112] Alternatively, the synthetically derived lubricating base oil may be selected from, for example, esters formed from synthetic or animal- or plant-derived carboxylic acids and various alcohols or polyols; or esters formed from carbonic acid and various alcohols and polyols.

[0113] Plant-derived lubricating base oils may be selected from, for example, soybean oil, palm oil, castor oil, or mixtures thereof.

[0114] Animal-derived lubricating base oils may be selected from, for example, tallow, lard, whale oil, or mixtures thereof.

[0115] Another method for classifying 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).

[0116] According to the above classification method (API), lubricating base oils are divided into five categories based on their chemical-physical properties and compositional characteristics.

[0117] According to the above classification model (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 I, II and III.

[0118] As described above, the present invention also relates to a lubricating oil composition comprising at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) (as is or in concentrated solution) and at least one lubricating base oil selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof.

[0119] Therefore, the present invention also relates to a lubricating oil composition comprising at least one lubricating base oil and at least one hydrogenated multiblock linear styrene-butadiene copolymer (as is) having general formula (I) or (II), wherein the lubricating base oil is selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof, and the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) is present in the lubricating oil composition in an amount of 0.1% to 5% by weight, preferably 0.2% to 2% by weight, relative to the total weight of the lubricating oil composition.

[0120] The present invention also relates to a lubricating oil composition comprising at least one lubricating base oil and at least one concentrated solution of at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II), wherein the lubricating base oil is selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof, and the concentrated solution is present in the lubricating composition in an amount of 0.5% to 50% by weight, preferably 3.5% to 30% by weight, and more preferably 5% to 15% by weight, relative to the total weight of the lubricating composition.

[0121] In addition to at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II), the above-mentioned lubricating oil composition may contain other additives capable of increasing viscosity index, detergent additives, dispersant additives, antioxidant additives, friction modifiers, wear-resistant and extreme pressure additives (EP additives), corrosion inhibitors, pour point depressant additives, foam inhibitors, emulsifiers, mixtures thereof, etc.

[0122] To better understand and put the invention into practice, some illustrative and non-limiting embodiments of the invention are reported below.

[0123] Use the analytical and characterization methods reported below.

[0124] 1 H-NMR spectrum

[0125] The quantitative determination of the microstructure (content of units with configurations 1 and 2) and polymer composition (total content of 1,3-butadiene) of the hydrogenated linear multiblock styrene-butadiene copolymer described in this invention was performed according to ISO 21561-1:2015 standard, by analyzing the unhydrogenated linear multiblock styrene-butadiene copolymer (“parent polymer”). 1 The determination was made using H-NMR spectroscopy.

[0126] Recordings were performed at room temperature (25°C) and 50°C using a Bruker Avance 300 nuclear magnetic resonance spectrometer equipped with a 5mm probe and variable temperature. 1H-NMR spectrum.

[0127] For this purpose, a polymer solution of an unhydrogenated multiblock linear styrene-butadiene copolymer (“parent polymer”) obtained as reported in the following examples, at a concentration of 3% w / v (g / mL), was prepared using deuterated chloroform (CDCl3) (Merck - purity >99.8%) with the addition of 0.03% wt. tetramethylsilane (TMS) (Merck) (internal standard).

[0128] Determination of molecular weight

[0129] The weight-average molecular weight (Mb) of the hydrogenated linear multiblock styrene-butadiene copolymers obtained as reported in the following examples was determined by GPC (“gel permeation chromatography”) using an Agilent Technologies 1200 series integrated instrument with fixed wavelength UV detection (254 nm), under the following conditions. w Number-average molecular weight (M) n ) and the Multidispersion Index (PDI) (M w / M n The determination of )

[0130] - Six Agilent Technologies GPC PL columns, each 300 x 7.5 mm in size, are as follows:

[0131] type Particle size Porosity (Å) PLGEL 5 μm <![CDATA[10 5 <!-- 9 -->]]> 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

[0132] - Mettler Toledo analyzes the balance scale;

[0133] - Laboratory glassware;

[0134] - Oscillator;

[0135] - Column injection temperature: 25℃;

[0136] - Column temperature and detector: 25℃;

[0137] - Solvent / eluent: Tetrahydrofuran (THF) (HPLC grade 99+% - Merck);

[0138] - Flow rate: 1 mL / min;

[0139] - Calculate molecular weight using a universal calibration curve.

[0140] The above operating conditions are continuously monitored via a personal computer equipped with Agilent Technologies' Agilent GPC / SEC software.

[0141] The calibration is performed as follows.

[0142] 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 different nominal peak molecular weights (M0.05) of the above standards used for calibration curves... p The range is approximately 3 kDa to 10 kDa.

[0143] Different solutions were prepared by stirring at room temperature (25°C).

[0144] Using a personal computer equipped with the aforementioned Agilent Technologies GPC / SEC software, the calibration curve is calculated using a third-order polynomial function: the molecular weight information can be obtained through this polynomial.

[0145] Determination of degree of hydrogenation (GI)

[0146] The degree of hydrogenation (GI) of the hydrogenated multiblock linear styrene-butadiene copolymers obtained as reported in the following examples was determined by Fourier transform infrared spectroscopy (FTIR) using a THERMO FISHER NICOLET iS50 spectrophotometer and under the following conditions:

[0147] - Transmission measurement;

[0148] - Spectral range: 1050-650 cm⁻¹ -1 ;

[0149] -Number of scans: 25;

[0150] - Resolution: 4 cm -1 ;

[0151] - Gain: 1;

[0152] - The moving speed of the mirror in the interferometer: 0.6329 cm / s;

[0153] - Slit opening: 65.

[0154] The main instrument features are:

[0155] -OMNIC software version 9.12;

[0156] - Spectral range: 4000-400 cm⁻¹ -1 ;

[0157] - Single beam;

[0158] - Detector: TGS (triglycine deuterated sulfate).

[0159] An unhydrogenated multiblock linear styrene-butadiene copolymer (“parent polymer”) with the same composition as the hydrogenated multiblock linear styrene-butadiene copolymer to be analyzed is used to calculate the calibration line.

[0160] For the aforementioned unhydrogenated multi-block linear styrene-butadiene copolymer (“parent polymer”), it is necessary to determine the absorbance of the functional groups under study. Specifically, the following conditions are applied:

[0161] Weigh approximately 0.8 g of the sample into a 20 ml screw-cap vial, then add approximately 10 ml of cyclohexane (Merck) (~10% w / w), and place all the contents in a shaker until completely dissolved;

[0162] - The obtained polymer solution was spread into a thin layer on a rectangular window (40×20 mm, 5 mm thick) of potassium bromide using a glass rod, and the solvent was evaporated using a nitrogen stream.

[0163] -through 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.

[0164] - By inserting a window along the optical path of the IR beam 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). -1 The 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, the obtained values ​​must be ignored, and the sample analysis must be repeated.

[0165] - at approximately 968 cm -1 (At), 910 cm -1 (Av) and 700cm -1 The maximum absorbance was measured at (As);

[0166] - For the "parent polymer", measure the ratio (At + Av) / As and plot it; for the fully hydrogenated polymer, the ratio (At + Av) / As will equal 0; calculate the equation of the linear line y=aX + b interpolated between the two points (e.g., Figure 1 (As reported).

[0167] Calculate the degree of hydrogenation using the following expression:

[0168]

[0169] in:

[0170] - Av = Vinyl absorbance (910 cm⁻¹) -1 );

[0171] - At = Absorbance of the trans structure (968 cm⁻¹) -1 );

[0172] - As = absorbance of styrene (700 cm⁻¹) -1 );

[0173] - a = angle coefficient of the line;

[0174] - b = the intercept of the line on the y-axis.

[0175] Determination of thickening capacity (TP)

[0176] For this purpose, the hydrogenated multiblock styrene-butadiene copolymer obtained as reported in the following examples was dissolved in reference base oil SN 150 Group I (Eni SpA) in an amount equal to 1% by weight.

[0177] Thickening capacity (TP) is calculated using the following formula, where the kinematic viscosity (KV) at 100°C is determined according to ASTM D445-21e2 standard:

[0178] TP=KV100℃ （油+聚合物1重量%） -KV100℃ （油） .

[0179] Determination of Shear Stability Index (SSI)

[0180] For this purpose, the hydrogenated multiblock linear styrene-butadiene copolymer obtained as reported in the following examples was dissolved in reference base oil SN 150 Group I (Eni SpA) in an amount equal to 1.2% by weight, and additive MX 4333 (Eni SpA) (“pour point depressant” - PPD) equal to 0.2% by weight of the total weight of the solution was added to the resulting solution.

[0181] The shear stability index (SSI) was determined according to the CEC-L-14-A-93 standard (30 shear cycles).

[0182] Determination of the shear stability of the finished lubricating composition (KV loss at 100℃)

[0183] For finished lubricant compositions, the percentage of kinematic viscosity (KV) loss at 100°C is determined according to CEC-L-14-A-93 standard (30 "shear cycles").

[0184] Measurement of cold viscosity ("Cold Start Simulator Viscosity" - "CCS Viscosity")

[0185] For this purpose, the hydrogenated multiblock linear styrene-butadiene copolymer obtained as reported in the following examples was dissolved in reference base oil SN 150 Group I (Eni SpA) in an amount equal to 1.2% by weight, and additive MX 4333 (Eni SpA) (“pour point depressant” - PPD) equal to 0.2% by weight of the total weight of the solution was added to the resulting solution.

[0186] Cold viscosity (“Cold Start Simulator Viscosity” - “CCS Viscosity”) was measured according to ASTM D5293-20 standard.

[0187] Determination of gelation index

[0188] For this purpose, the hydrogenated multiblock linear styrene-butadiene copolymer obtained as reported in the following examples was dissolved in reference base oil SN 150 Group I (Eni SpA) in an amount equal to 1.2% by weight, and additive MX 4333 (Eni SpA) (“pour point depressant” - PPD) equal to 0.2% by weight of the total weight of the solution was added to the resulting solution.

[0189] The gelation index was measured using a Brookfield scanning device according to ASTM D5133-05 standard.

[0190] Pour point determination

[0191] For this purpose, the hydrogenated multiblock linear styrene-butadiene copolymer obtained as reported in the following examples was dissolved in reference base oil SN 150 Group I (Eni SpA) in an amount equal to 1.2% by weight, and additive MX 4333 (Eni SpA) (“pour point depressant” - PPD) equal to 0.2% by weight of the total weight of the solution was added to the resulting solution.

[0192] Pour point was measured according to ASTM D5950-14 standard.

[0193] Determination of the dispersion ability (porosity) of carbonaceous particles ("soot")

[0194] The dispersion capability is measured according to the method described and claimed in International Patent Application WO 2021 / 205360.

[0195] The method includes the following steps:

[0196] - A dispersion of carbon black Corax N550 (synthetic “smoke”) was prepared using a solution in reference base oil SN 150 Group I (Eni SpA), wherein the hydrogenated multiblock linear styrene-butadiene copolymer obtained as reported in the following examples was dissolved in an amount equal to 1.2% by weight.

[0197] - Dispersions obtained by analysis using an optical microscope with image acquisition capabilities;

[0198] - The dispersibility of solutions containing hydrogenated multiblock linear styrene-butadiene copolymer was evaluated using image analysis software, and "porosity" (i.e., a parameter for measuring the non-uniformity of the image) was determined: the higher the "porosity", the worse the dispersibility of the hydrogenated multiblock linear styrene-butadiene copolymer.

[0199] Further details about the method can be found in Example 8 below.

[0200] Measurement of kinematic viscosity

[0201] The kinematic viscosity of a lubricating oil composition containing a hydrogenated multiblock linear styrene-butadiene copolymer as reported in the following examples was measured according to ASTM D445-21e2.

[0202] Determination of viscosity index

[0203] The viscosity index of lubricating oil compositions containing hydrogenated multiblock linear styrene-butadiene copolymers as reported in the following examples was measured according to ASTM D2270-10 (2016).

[0204] Determination of viscosity at high temperature and high shear rate (HTHS)

[0205] The viscosity of a lubricating oil composition containing a hydrogenated multiblock linear styrene-butadiene copolymer as reported in the following examples was measured at high temperature and high shear rate (HTHS) according to CEC-L-36-A-90 standard.

[0206] Examples 1-2 (Invention) - Example 3 (Comparative)

[0207] Preparation of hydrogenated multiblock linear styrene-butadiene copolymer

[0208] Three hydrogenated multiblock linear styrene-butadiene copolymers were prepared as described below.

[0209] The suspension polymerization batch reaction is carried out in a 20 L batch reactor (15 L of which is the effective volume), which is equipped with impeller blades, an anchor-type bottom scraper, a bottom discharge port and a cooling jacket.

[0210] Anhydrous cyclohexane (Cepsa) is fed into the reactor, and after the temperature is raised to 27°C, tetrahydrofuran (THF) (VWR International) is added, followed by the following reaction:

[0211] Reaction 1 [Step (a)]:

[0212] - Add anhydrous 1,3-butadiene (Versalis SpA);

[0213] - Add n-butyllithium (15% hexane solution) (Merck) (NBL);

[0214] - Waiting time for response.

[0215] Reaction 2 [Step (b)]:

[0216] - Add anhydrous styrene (Versalis SpA);

[0217] - Waiting time for response.

[0218] Reaction 3 [Step (c)]:

[0219] - Add anhydrous 1,3-butadiene (Versalis SpA);

[0220] - Waiting for reaction time (polymerization);

[0221] - Add diphenyldichlorosilane (Ametech) (DFClSi);

[0222] - Waiting time for response (coupling).

[0223] Hydrogenation reaction [step (d)]:

[0224] - Add butyl ethyl magnesium chloride (Nouryon);

[0225] - Added bis(cyclopentadienyl)titanium dichloride (Nouryon);

[0226] - Waiting time for response.

[0227] Table 1 reports the operating conditions used: the compound fed into the reactor, the temperature, and the reaction duration.

[0228] The obtained solution of hydrogenated multiblock linear styrene-butadiene copolymer was discharged from the bottom of the reactor and transferred to a storage container. Subsequently, the solution was continuously fed into a stripping tower containing water at 90°C, and water vapor was also fed into the stripping tower to strip the unreacted monomers (1,3-butadiene and styrene) and solvent.

[0229] The water leaving the stripping tower is collected and transported for water treatment.

[0230] The obtained hydrogenated multiblock linear styrene-butadiene copolymer was characterized as described above, and the results are reported in Table 2.

[0231] Table 1

[0232]

[0233] (1) ppm refers to the total amount of added monomers (1,3-butadiene and styrene).

[0234] Table 2

[0235]

[0236] (1) M of hydrogenated multiblock linear styrene-butadiene copolymer w [M determined by non-hydrogenated multi-block linear styrene-butadiene copolymer (“parent polymer”)] w ];

[0237] (2) M of total bound styrene (S1+S2) in hydrogenated multiblock linear styrene-butadiene copolymer w [M determined by non-hydrogenated multi-block linear styrene-butadiene copolymer (“parent polymer”)] w ];

[0238] (3) M of the EB1, EB2 and EB3 blocks of hydrogenated multiblock linear styrene-butadiene copolymer w [M determined by non-hydrogenated multi-block linear styrene-butadiene copolymer (“parent polymer”)] w ];

[0239] (4) : The weight percentage of the total weight of butadiene units in the hydrogenated multiblock linear styrene-butadiene copolymer (by weight percentage of the non-hydrogenated multiblock linear styrene-butadiene copolymer (“parent polymer”)).

[0240] Examples 4-5 (Invention) - Example 6 (Comparative)

[0241] Hydrogenated multiblock linear styrene-butadiene copolymer added as a lubricating oil viscosity index improver (VII) Evaluation of agents

[0242] For this purpose, the hydrogenated multiblock linear styrene-butadiene copolymers obtained in Examples 1-2 (the present invention) and Example 3 (comparative) were dissolved in reference base oil SN 150 Group I (EniS.pA) in amounts of 1 wt% and 1.2 wt%, respectively.

[0243] The thickening capacity (“TP”) was determined by dissolving the hydrogenated multiblock linear styrene-butadiene copolymers obtained in Examples 1-2 (the present invention) and Example 3 (comparative) in a solution obtained by dissolving the solution in a amount equal to 1% by weight in the reference base oil SN 150 Group I (Eni SpA) as described above: the results obtained are reported in Table 3.

[0244] The solutions obtained by dissolving the hydrogenated multiblock linear styrene-butadiene copolymers obtained in Examples 1-2 (the present invention) and Example 3 (comparative) in a reference base oil SN 150 Group I (Eni SpA) at an amount equal to 1.2% by weight and adding additive MX 4333 (EniS.pA) (pour point depressant - PPD) at an amount equal to 0.2% by weight relative to the total weight of the solution were characterized as described above to determine the shear stability index (SSI), cold viscosity ("cold start simulator viscosity" - "CCS viscosity"), pour point, and gelation index: the results obtained are reported in Table 3.

[0245] Example 7 (Comparative)

[0246] Evaluation of commercial olefin copolymer (OCP) lubricants as lubricant viscosity index improver (VII) additives.

[0247] For this purpose, commercial olefin copolymer (OCP) MX 4006 (Eni SpA) was dissolved in reference base oil SN 150 Group I (Eni SpA) at amounts of 1 wt% and 1.2 wt%.

[0248] The thickening capacity (TP) was determined by dissolving a commercial olefin copolymer (OCP) MX 4006 (Eni SpA) in a solution equal to 1% by weight in a reference base oil SN 150 Group I (Eni SpA) as described above: the results obtained are reported in Table 3.

[0249] The solution obtained by dissolving commercially available olefin copolymer (“OCP”) MX 4006 (Eni SpA) in a 1.2% by weight amount in reference base oil SN 150 Group I (Eni SpA) and adding 0.2% by weight of additive MX 4333 (Eni SpA) (pour point depressant - PPD) equal to the total weight of the solution to the obtained solution was characterized as described above to determine the shear stability index (SSI), cold viscosity (“cold start simulator viscosity” - “CCS viscosity”), pour point, and gelation index (gelation index): the results obtained are reported in Table 3.

[0250] Table 3

[0251]

[0252] Examples 8-9 (Invention) - Examples 10-11 (Comparative)

[0253] The ratio of dispersing power of hydrogenated multiblock linear styrene-butadiene copolymer to commercial olefin copolymer (OCP) Comparative evaluation

[0254] For this purpose, the hydrogenated multiblock linear styrene-butadiene copolymer and commercial olefin copolymer (“olefin copolymer”-OCP) MX 4006 (Eni SpA) obtained in Examples 1-2 (the present invention) and Example 3 (comparative) were dissolved in reference base oil SN 150 Group I (Eni SpA) in an amount equal to 1.2% by weight, and additive MX 4333 (Eni SpA) was added to the obtained solution in an amount equal to 0.2% by weight relative to the total weight of the solution.

[0255] A mixture containing the above solution and 4.5% Corax N550 carbonaceous particles was then prepared, expressed as a weight percentage of the total mixture. The resulting mixture was mixed for 10 minutes using a stirrer (IKA, model VORTEX3) running at 1500 rpm. Subsequently, the mixture was homogenized for 15 minutes using an IKA Ultra-Turrax T25 digital homogenizer with an S25N-8G head running at 20000 rpm at 75°C. At the end of this operation, a homogenized paste was obtained. The obtained homogenized paste was equilibrated for 28 hours using a track-type thermal stirrer (Torrey Pines Scientific, model ECHOTHERM SC20) running at 300 rpm at 75°C. At the end of this operation, a final dispersion was obtained, ready for analysis using an optical microscope.

[0256] Analysis was performed using an optical microscope equipped with a 10X objective lens (Nikon, model Diaphot 300, with a CCD Nikon Digital Sight DS-5M-U1, light source: 50 W halogen bulb), with the sample maintained at 100°C using a temperature-controlled stage (LINKAM, model PE94 Inverted Peltier Systems). Samples for analysis were prepared by depositing 4 µL between two circular microscope slides, each 0.15 mm thick and 35 mm in diameter. Optical micrographs were then obtained, their images acquired, and the dispersion determined. The dispersion was calculated using an image descriptor (i.e., porosity (λ)).

[0257] Porosity is a measure of how well a spatial pattern fills space, with patterns having more and / or larger gaps (voids) having greater porosity. Porosity is calculated using an algorithm that can be implemented by a program (software). The program used is the open-source software FracLac (version 2.5), which is available as a plugin for ImageJ (version 1.5.3).

[0258] Table 4 shows the results obtained, from which it can be inferred that the hydrogenated linear multiblock styrene-butadiene copolymers obtained in Examples 1-2 (of the present invention) covered by the present invention have excellent dispersibility (low porosity value) compared to the hydrogenated linear multiblock styrene-butadiene copolymer with lower styrene content obtained in Example 3 (comparative) and compared to the commercial olefin copolymer (“olefin copolymer” OCP) MX 4006 (Eni SpA).

[0259] Table 4

[0260]

[0261] Example 12

[0262] Concentrated solution of hydrogenated multiblock linear styrene-butadiene copolymer

[0263] A concentrated solution was prepared by dissolving the hydrogenated multiblock linear styrene-butadiene copolymer obtained in Example 2 (of the present invention) in a reference base oil SN 150 Group I (Eni SpA) at an amount equal to 10% by weight. To avoid discoloration of the solution, the process was carried out at 130°C for 120 minutes in an inert nitrogen atmosphere in a device equipped with a mechanical paddle stirrer. The resulting solution appeared as a clear liquid and remained so at temperatures down to -5°C, exhibiting no gelation during cooling. The kinematic viscosity of the concentrated solution at 100°C, measured according to ASTM D445-21e2, was 950 mmHg. 2 / s.

[0264] Example 13

[0265] Lubricating oil composition containing concentrated solution of hydrogenated multiblock linear styrene-butadiene copolymer

[0266] A lubricating oil composition for heavy-duty diesel engines was prepared by mixing a concentrated solution of the hydrogenated multiblock linear styrene-butadiene copolymer obtained in Example 12 (of the present invention) with a mixture of commercially available Group II (API classification) base oils consisting of Chevron 220 R and Chevron 100 R base oils, wherein the amounts of various components are reported in Table 5, and the following components were added thereto:

[0267] - MX 5217 Composite Pack (Eni SpA) contains calcium sulfonate and magnesium sulfonate detergents, dispersants, antioxidant additives, abrasion-resistant additives, and...

[0268] Additive MX 4333 (Eni SpA) (“Pour Point Decrease” - PPD);

[0269] Table 5

[0270]

[0271] The obtained lubricating oil composition was characterized as described above to determine kinematic viscosity at 100°C and 40°C, viscosity index, cold viscosity (“cold start simulator viscosity” – “CCS viscosity”), high temperature and high shear rate (HTHS) viscosity, pour point, gel index, mechanical stability as measured by kinematic viscosity (KV) loss at 100°C, and dispersibility: the results obtained are reported in Table 6.

[0272]

[0273] Table 6

[0274] The data reported in Table 6 indicate that the hydrogenated multiblock linear styrene-butadiene copolymer of the present invention (the concentrated solution obtained in Example 12) can provide a lubricating oil composition with excellent mechanical stability, as evidenced by the low kinematic viscosity (KV) loss at 100°C, good thermal thickening (kinematic viscosity at 100°C), and almost no effect on cold viscosity (CCS at -25°C). Furthermore, the low gel index and low pour point of the lubricating oil composition make this copolymer highly suitable for preparing lubricating oil compositions that can be used in very cold climates. Finally, the copolymer provides excellent dispersibility ("porosity") for carbonaceous particles ("ash") in the lubricating oil composition, as indicated by a porosity value close to 0.

Claims

1. A hydrogenated multiblock linear styrene-butadiene copolymer having the general formula (I) or (II): (EB)1-S1-(EB)3-S2-(EB)2 (I) (EB)1-S1-(EB)2 (II) in: - (EB)1, (EB)2 and (EB)3 represent hydrogenated polymer blocks derived from 1,3-butadiene; - S1 and S2 represent polymer blocks derived from styrene; in: - In general formula (I), the amount of the polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 56% to 74% by weight, preferably 64% to 70% by weight, relative to the total weight of the copolymer, the amount being defined as the sum of [(EB)1 + (EB)2]; the amount of the polymer block (EB)3 derived from 1,3-butadiene is 1% to 4% by weight, preferably 1% to 2% by weight, relative to the total weight of the copolymer; and the amount of the polymer blocks S1 and S2 derived from styrene is 25% to 40% by weight, preferably 29% to 34% by weight, relative to the total weight of the copolymer, the amount being defined as the sum of S1 + S2; - In general formula (II), the 1,3-butadiene-derived polymer blocks (EB)1 and (EB)2 are present in an amount of 60% to 75% by weight, preferably 66% to 71% by weight, relative to the total weight of the copolymer, the amount being defined as the sum of [(EB)1 + (EB)2], and the styrene-derived polymer block S1 is present in an amount of 25% to 40% by weight, preferably 29% to 34% by weight, relative to the total weight of the copolymer; - In the polymer blocks (EB)1, (EB)2 and (EB)3 derived from 1,3-butadiene, the content of polybutadiene units having configurations 1,2 is 45% to 70% by weight, preferably 50% to 65% by weight, relative to the total weight of the butadiene units, and the content of units having configurations 1,4 is 30% to 55% by weight, preferably 35% to 50% by weight, relative to the total weight of the butadiene units.

2. The hydrogenated multi-block linear styrene-butadiene copolymer according to claim 1, has the following characteristics: - The weight-average molecular weight (M) of each of the polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene w The weight-average molecular weight (Mn) of each of the two polymer blocks (EB)1 and (EB)2 derived from 1,3-butadiene is 29,000 Da to 60,000 Da, preferably 30,000 Da to 48,000 Da. w If they are equal or different, they are preferred to be equal. - Weight average molecular weight (M) of polymer block (EB)3 derived from 1,3-butadiene w The range is 900 Da to 6000 Da, preferably 1000 Da to 2800 Da; - Weight-average molecular weight (M) of styrene-derived polymer blocks (S1 or S1+S2) w The value ranges from 25,000 Da to 55,000 Da, preferably from 26,000 Da to 48,000 Da; - The degree of hydrogenation of the three polymer blocks (EB)1, (EB)2 and (EB)3 derived from 1,3-butadiene is greater than or equal to 98%, preferably greater than or equal to 99%, and more preferably equal to 100%; - Weight-average molecular weight (M) of hydrogenated multiblock linear styrene-butadiene copolymer w The range is 90,000 to 181,000 Daltons, preferably 113,000 to 147,000 Daltons; - Corresponding to M w / M n The polydispersity index (PDI) of the ratio is 0.98 to 1.2, preferably 1.0 to 1.

1.

3. The hydrogenated multi-block linear styrene-butadiene copolymer according to claim 1 or 2, having the following characteristics: - Shear stability index (SSI) of 3% to 20%, preferably 5% to 15%, measured in Group I base oils according to CEC-L-14-A-93 standard (30 "shear cycles"); - Thickening capacity (TP) is 2.5 mm. 2 / s to 5 mm 2 / s, preferably 2.8 mm 2 / s to 4.5 mm 2 / s, measured in Group I base oils according to ASTM D445-21e2 standard; - The cold viscosity at -25°C ("cold start simulator viscosity" - "CCS viscosity") is 5000 cP to 6800 cP, preferably 5500 cP to 6500 cP, measured in Group I base oils according to ASTM D5293-20 in the presence of additive MX 4333 (Eni SpA) ("pour point depressant" - PPD); - The cold viscosity at -20°C ("cold start simulator viscosity" - "CCS viscosity") is 2500 cP to 3400 cP, preferably 2700 cP to 3100 cP, measured in Group I base oils according to ASTM D5293-20 in the presence of additive MX 4333 (Eni SpA) ("pour point depressant" - PPD); - Pour point below -25°C, preferably -27°C to -45°C, measured in Group I base oils according to ASTM D5950-14 in the presence of additive MX 4333 (Eni SpA) ("pour point depressant" - PPD); - The gel index is 3 to 10, preferably 5 to 8, measured in Group I base oils according to ASTM D5133-05 in the presence of additive MX 4333 (Eni SpA) ("pour point depressant" - PPD).

4. The hydrogenated multiblock linear styrene-butadiene copolymer according to any one of claims 1 to 3, which has the ability to disperse carbonaceous particles ("soot") in a lubricating oil composition, measured by a porosity value of 0 to 1, preferably 0.05 to 0.

80.

5. A batch method for preparing the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) according to claim 1, 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 to obtain block (EB)1. (b) Add styrene to the polymer mixture obtained in step (a) and continue the living polymerization until the styrene is substantially completely converted, thereby obtaining blocks (EB)1-S1 and S2-(EB)2. (c) Relative to the total weight of the butadiene-styrene copolymer obtained in step (b), 1,3-butadiene is added to the polymerization mixture obtained in step (b) in an amount equal to 2% by weight, preferably equal to 1% by weight, more preferably equal to 0.5% by weight, and the living polymerization is continued until the 1,3-butadiene is substantially completely converted. Subsequently, at least one coupling agent is added to the obtained polymerization mixture to obtain a multi-block linear styrene-butadiene copolymer (EB)1-S1-(EB)3-S2-(EB)2, wherein the blocks (EB)1 and (EB)2 are identical and the blocks S1 and S2 are identical. (d) The multi-block linear styrene-butadiene copolymer obtained in step (c) is hydrogenated to obtain a hydrogenated multi-block linear styrene-butadiene copolymer having the general formula (I).

6. An intermittent method for preparing a hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) according to claim 5, 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; 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 the general formula (III): R1(Li) n (III) Where R1 represents C1-C of a straight chain or a branch chain. 20 C2-C is preferred. 12 Alkyl, C3-C 30 C4-C is preferred. 10 cycloalkyl, C6-C 30 C6-C is preferred. 12 Aryl group, and n is an integer from 1 to 4; preferably, it is selected from: 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; even more preferably it is n-butyllithium; and / or - The at least one polar modifier is selected from: acyclic 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 coupling agent is selected from dimethyldichlorosilane, diphenyldichlorosilane, methylphenyldichlorosilane or mixtures thereof, preferably diphenyldichlorosilane.

7. An intermittent method for preparing a hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) according to claim 5 or 6, wherein: - Step (a) is performed at a temperature of 20°C to 100°C, preferably 25°C to 85°C; and / or for a duration of 10 minutes to 1 hour, preferably 20 minutes to 40 minutes; and / or - Step (b) is performed at a temperature of 40°C to 110°C, preferably 50°C to 95°C; and / or for a duration of 1 minute to 9 minutes, preferably 3 minutes to 7 minutes; and / or - Step (c) is performed at a temperature of 45°C to 115°C, preferably 55°C to 100°C, and / or for a duration of 3 to 30 minutes, preferably 5 to 20 minutes.

8. A batch method for preparing the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (II) according to claim 1, 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 to obtain block (EB)1. (b') Add styrene to the polymerization mixture obtained in step (a') and continue the living polymerization until the styrene is substantially completely converted, thereby obtaining block (EB)1-S1; (c') Add 1,3-butadiene to the polymerization mixture obtained in step (b') and continue the living polymerization until the 1,3-butadiene is substantially completely converted to obtain a linear multiblock styrene-butadiene copolymer (EB)1-S1-(EB)2, wherein the blocks (EB)1 and (EB)2 are the same as or different from each other. (d') Add at least one terminating agent to the polymerization mixture obtained in step (c'); (e') The multi-block linear styrene-butadiene copolymer obtained in step (d') is hydrogenated to obtain a hydrogenated multi-block linear styrene-butadiene copolymer having the general formula (II).

9. An intermittent method for preparing a hydrogenated multiblock linear styrene-butadiene copolymer having general formula (II) according to claim 8, wherein: - The at least one hydrocarbon solvent, the at least one lithium-based initiator, and the at least one polar modifier are selected from those described in claim 6; and / or - The at least one terminating agent is selected from trimethylchlorosilane, butanol, octanol or a mixture thereof; preferably it is trimethyldichlorosilane.

10. An intermittent method for preparing a hydrogenated multiblock linear styrene-butadiene copolymer having general formula (II) according to claim 8 or 9, wherein: - Step (a') is performed at a temperature of 20°C to 60°C, preferably 25°C to 55°C; and / or for a duration 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 75°C, preferably 35°C to 70°C; and / or for a duration of 1 minute to 9 minutes, preferably 3 minutes to 7 minutes; and / or - Step (c') is performed at a temperature of 45°C to 115°C, preferably 45°C to 100°C; and / or for a duration of 10 minutes to 1 hour, preferably 20 minutes to 40 minutes; and / or - The step (d') is performed at a temperature of 45°C to 115°C, preferably 55°C to 110°C, and / or for a duration of 1 minute to 10 minutes, preferably 3 minutes to 8 minutes.

11. A concentrated solution, which contains: - Relative to the total weight of the concentrated solution, 3% to 30% by weight, preferably 5% to 25% by weight, more preferably 8% to 15% by weight of at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) according to any one of claims 1 to 10; - Relative to the total weight of the concentrated solution, 70% to 97% by weight, preferably 75% to 95% by weight, more preferably 85% to 92% by weight, of at least one lubricating base oil, said lubricating base oil being selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof.

12. A lubricating oil composition comprising at least one lubricating base oil and at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) according to any one of claims 1 to 10, wherein the lubricating base oil is selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof, and the hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) is present in the lubricating oil composition in an amount of 0.1% to 5% by weight, preferably 0.2% to 2% by weight, relative to the total weight of the lubricating oil composition.

13. A lubricating oil composition comprising at least one lubricating base oil and at least one concentrated solution of at least one hydrogenated multiblock linear styrene-butadiene copolymer having general formula (I) or (II) according to any one of claims 1 to 10, wherein the lubricating base oil is selected from mineral-derived, synthetic-derived, animal-derived, plant-derived lubricating base oils or mixtures thereof, and the concentrated solution is present in the lubricating composition in an amount of 0.5% to 50% by weight, preferably 3.5% to 30% by weight, and more preferably 5% to 15% by weight, relative to the total weight of the lubricating composition.

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