Copolymer containing cyclohexyl structure as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lubricating oil additives, and discloses a copolymer containing a cyclohexyl structure as well as a preparation method and application thereof. The copolymer contains at least three segments of block structures and at least two segments of random gradient structures, and contains a cyclohexyl structure; the general formula of the copolymer is C1-CA1-B-A2-C2, a C1 segment and a C2 segment are of block structures, and each of the C1 segment and the C2 segment independently comprises a structural unit as shown in a formula (1); the section A1 and the section A2 are of random gradual change structures, and each of the section A1 and the section A2 independently comprises a structural unit as shown in a formula (1) and a structural unit as shown in a formula (2); the segment B is of a homopolymerized block structure; and the segment B comprises a structural unit as shown in a formula (2). The copolymer disclosed by the invention has relatively good high-temperature tackifying effect, high-temperature anti-shearing capability and low-temperature fluidity, and can be used as a viscosity index improver of lubricating oil. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the technical field of lubricating oil additives, and in particular to a copolymer containing a cyclohexyl structure and a preparation method and application thereof. Background Art

[0002] Modern internal combustion engine multi-grade oils have put forward higher and higher requirements on the viscosity of lubricating oils in a wide temperature range, which makes the requirements for viscosity index improvers higher and higher. Polymers commonly used as viscosity index improvers include ethylene-propylene copolymer (OCP), hydrogenated styrene conjugated diene copolymer (HSD), methacrylates, polyisobutylene, etc.

[0003] Ethylene-propylene copolymer viscosity index improvers have good thickening ability and shear stability, strong high-temperature shear resistance, and are widely used in internal combustion engine oils. However, the low-temperature performance of this type of viscosity index improver is poor (that is, the apparent viscosity or flow performance of the lubricating oil is poor at low temperatures), and it is usually necessary to add a pour point depressant to improve its low-temperature performance. In addition, the low-temperature performance and high-temperature shear resistance of viscosity index improvers are usually contradictory. Viscosity index improvers with higher thickening ability usually have higher molecular weights, but in order to obtain better low-temperature performance, relatively low molecular weights are usually required; thus, it is difficult to obtain viscosity index improvers with good thickening ability and shear stability, as well as good low-temperature performance.

[0004] HSD type viscosity index improvers usually have good viscosity increasing and shear stability. Usually, styrene / butadiene or isoprene copolymers are hydrogenated to produce viscosity index improvers with good oxidation stability, thickening ability and shear stability. The main disadvantage is that the viscosity is low at high temperature and high shear rate.

[0005] US4116917A discloses hydrogenated butadiene / isoprene star polymers and isoprene star polymers. The chain segments generated after hydrogenation are similar to high-ethylene content OCPs, which are prone to crystallization and result in poor low-temperature performance.

[0006] CN1576359A discloses the use of linear or star-shaped random copolymers of partially hydrogenated isoprene and butadiene as lubricating oil viscosity index improvers. However, the viscosity index improvers still cannot achieve good high-temperature viscosity increasing effect, high-temperature shear resistance and low-temperature fluidity.

[0007] In summary, it is difficult for the various lubricant viscosity modifiers currently used to simultaneously achieve ideal effects in terms of low-temperature fluidity, high-temperature viscosity-increasing effect, and high-temperature shear resistance. Summary of the invention

[0008] The purpose of the present invention is to overcome the problem that various lubricating oil viscosity modifiers in the prior art are difficult to achieve ideal effects of low-temperature fluidity, high-temperature viscosity-increasing effect and high-temperature shear resistance at the same time, and to provide a copolymer containing a cyclohexyl structure and a preparation method and application thereof, wherein the copolymer can have good high-temperature viscosity-increasing effect, high-temperature shear resistance and low-temperature fluidity.

[0009] In order to achieve the above-mentioned object, the first aspect of the present invention provides a copolymer containing a cyclohexyl structure, wherein the copolymer contains at least three block structures, at least two random gradient structures, and contains a cyclohexyl structure; the general formula of the copolymer is C1-A1-B-A2-C2, wherein the C1 segment and the C2 segment are block structures, and the C1 segment and the C2 segment each independently include the structural unit shown in formula (1); the A1 segment and the A2 segment are random gradient structures, and the A1 segment and the A2 segment each independently include the structural unit shown in formula (1) and the structural unit shown in formula (2); the B segment is a homopolymer block structure; the B segment includes the structural unit shown in formula (2);

[0010]

[0011] Wherein, R1 and R2 are each independently H or a substituted or unsubstituted cyclohexyl group, and R1 and R2 are not H at the same time; R3, R4, R5 and R6 are each independently H or a C1-C4 alkyl group, and R3, R4, R5 and R6 are not H at the same time.

[0012] The second aspect of the present invention provides a method for preparing a copolymer containing a cyclohexyl structure, the preparation method comprising the following steps:

[0013] (1) in a non-polar hydrocarbon solvent, in the presence of a polarity regulator and an organic lithium initiator, subjecting a first monovinyl aromatic monomer to a first polymerization reaction to obtain an active polymerization section S1;

[0014] (2) subjecting the active polymerization section S1 to a second polymerization reaction with a first conjugated diene monomer and a second monovinyl aromatic monomer to obtain an active polymerization section S2;

[0015] (3) subjecting the active polymerization section S2 to a third polymerization reaction with a second conjugated diene monomer to obtain an active polymerization section S3;

[0016] (4) subjecting the active polymerization section S3 to a fourth polymerization reaction with a third conjugated diene monomer and a third monovinyl aromatic monomer to obtain an active polymerization section S4;

[0017] (5) subjecting the active polymerization section S4 to a fifth polymerization reaction with a fourth monovinyl aromatic monomer to obtain a copolymer precursor;

[0018] (6) subjecting the copolymer precursor to a hydrogenation reaction in the presence of a hydrogenation catalyst, so that at least 98% of the unsaturated double bonds of the structural units derived from the conjugated diene are hydrogenated; and at least 95% of the unsaturated double bonds of the structural units derived from the monovinyl aromatic hydrocarbon are hydrogenated, to obtain a copolymer containing a cyclohexyl structure.

[0019] The third aspect of the present invention provides a copolymer containing a cyclohexyl structure obtained by the aforementioned preparation method.

[0020] A fourth aspect of the present invention provides use of the aforementioned copolymer containing a cyclohexyl structure in lubricating oil.

[0021] A fifth aspect of the present invention provides a lubricating oil composition, comprising a base oil and a viscosity index improver, wherein the viscosity index improver contains the aforementioned copolymer containing a cyclohexyl structure.

[0022] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0023] (1) The copolymer containing cyclohexyl structure proposed in the present invention is a multi-block copolymer containing cyclohexyl structure in the side chain, and the main chain of the copolymer contains at least three block structures and at least two random gradient structures; it can have good high-temperature viscosity increasing effect, high-temperature shear resistance and low-temperature fluidity.

[0024] (2) The copolymer containing a cyclohexyl structure of the present invention not only maintains the anti-shear stability of hydrogenated polyisoprene, but also takes into account the good thickening effect of hydrogenated polybutadiene. At the same time, the introduction of the polycyclohexyl structure reduces the crystallization of hydrogenated polybutadiene and increases the compatibility with lubricating oil base oil. It can be used as a viscosity index improver for lubricating oil. When used in a lubricating oil composition, the thickening ability, shear stability, low temperature performance and processing performance of the lubricating oil are significantly improved. In particular, it is used to prepare engine oil, so that it has a lower pumping viscosity and low temperature starting viscosity, and no crystallization or gel is generated. It is a viscosity index improver with excellent performance and can be widely used in the field of high-grade and large-span lubricating oils. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] The first aspect of the present invention provides a copolymer containing a cyclohexyl structure, wherein the copolymer contains at least three block structures, at least two random gradient structures, and contains a cyclohexyl structure; the general formula of the copolymer is C1-A1-B-A2-C2, wherein the C1 segment and the C2 segment are block structures, and the C1 segment and the C2 segment each independently include a structural unit shown in formula (1); the A1 segment and the A2 segment are random gradient structures, and the A1 segment and the A2 segment each independently include a structural unit shown in formula (1) and a structural unit shown in formula (2); the B segment is a homopolymer block structure; the B segment includes a structural unit shown in formula (2);

[0027]

[0028] Wherein, R1 and R2 are each independently H or a substituted or unsubstituted cyclohexyl group, and R1 and R2 are not H at the same time; R3, R4, R5 and R6 are each independently H or a C1-C4 alkyl group, and R3, R4, R5 and R6 are not H at the same time.

[0029] In the present invention, when R1 is H, R2 is a substituted or unsubstituted cyclohexyl group; when R1 is a substituted or unsubstituted cyclohexyl group, R2 is H; the substituted or unsubstituted cyclohexyl group can be selected from cyclohexyl groups, and can also be selected from cyclohexyl groups substituted by one or more C1-C5 alkyl groups.

[0030] In the present invention, the structural unit represented by formula (2) is derived from a conjugated diene structure by hydrogenation, R3, R4, R5 and R6 are each independently H or a C1-C4 alkyl group, and R3, R4, R5 and R6 are not H at the same time. Preferably, R3, R4, R5 and R6 are each independently H, methyl, ethyl, propyl, isopropyl or butyl, and at least one of R3, R4, R5 and R6 is not H.

[0031] In the present invention, the polymerization degrees of segment C1, segment A1, segment B, segment A2 and segment C2 are the same or different; segment A1 and segment A2 are the same or different, and the polymerization order of the structural unit represented by formula (1) and the structural unit represented by formula (2) is also random.

[0032] The copolymer of the present invention can have good high-temperature viscosity-increasing effect, high-temperature shear resistance and low-temperature fluidity.

[0033] In some embodiments, in the copolymer, based on the total mass of the copolymer, the mass content of the structural unit represented by formula (1) is 5-35%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, and any value in the range consisting of any two numerical values, preferably 10-30%; the mass content of the structural unit represented by formula (2) is 65-95%, for example, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and any value in the range consisting of any two numerical values, preferably 70-90%.

[0034] In some embodiments, the C1 segment and the C2 segment are each independently a block structure derived from monovinyl aromatic hydrocarbons and obtained by hydrogenation.

[0035] In some embodiments, the A1 segment and the A2 segment are each independently derived from a random gradient structure of monovinyl aromatic hydrocarbons and conjugated dienes and are obtained by hydrogenation.

[0036] In the present invention, the random gradient structure is a random copolymer block structure.

[0037] In some embodiments, the B segment is derived from a homopolymer block structure of a conjugated diene by hydrogenation.

[0038] In the copolymer of the present invention, at least 98% of the unsaturated double bonds of the structural units derived from the conjugated diene are hydrogenated; and at least 95% of the unsaturated double bonds of the structural units derived from the monovinyl aromatic hydrocarbon are hydrogenated.

[0039] In some embodiments, in the copolymer, at least 99% of the unsaturated double bonds of the structural units derived from the conjugated diene are hydrogenated; and at least 98% of the unsaturated double bonds of the structural units derived from the monovinyl aromatic hydrocarbon are hydrogenated.

[0040] According to the present invention, the monovinyl aromatic hydrocarbon refers to a compound in which one hydrogen on the aromatic ring is replaced by a vinyl group, and C1, C2, A1 and A2 all contain structural units derived from monovinyl aromatic hydrocarbon.

[0041] In some embodiments, the monovinyl aromatic hydrocarbon is a compound represented by Formula I,

[0042]

[0043] In Formula I, R7 is C6-C 20 The substituted or unsubstituted aryl group is preferably a phenyl group or a phenyl group substituted by one or more C1-C5 alkyl groups.

[0044] In the present invention, C6-C 20Specific examples of the substituted or unsubstituted aryl groups may include, but are not limited to, phenyl, o-tolyl, m-tolyl, p-tolyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, o-tert-butylphenyl, m-tert-butylphenyl, p-tert-butylphenyl, p-dodecylphenyl, 2,4-di-n-butylphenyl, p-n-propylphenyl and 2,4-diethylphenyl.

[0045] In some embodiments, the monovinyl aromatic hydrocarbon is selected from one or more of styrene, 2-methylstyrene, 4-methylstyrene, 4-tert-butylstyrene, 4-methylstyrene, 3,5-diethylstyrene, 3,5-di-n-butylstyrene, 4-n-propylstyrene and 4-dodecylstyrene.

[0046] In some preferred embodiments, the monovinyl aromatic hydrocarbon is selected from one or more of styrene, 2-methylstyrene and 4-methylstyrene.

[0047] According to the present invention, the conjugated diene compound refers to an unsaturated chain hydrocarbon containing a conjugated double bond (i.e., -C=CC=C-) in the molecular structure, and can be various conjugated dienes commonly used in the art, without particular limitation. For example, the conjugated diene can be one or more conjugated dienes selected from C4-C8.

[0048] In some embodiments, the conjugated diene is selected from one or more of butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene and 2,3-dimethylbutadiene; more preferably, the conjugated diene is butadiene and / or isoprene.

[0049] In some embodiments, in the copolymer, the molar content of 1,2-structure in the structural units derived from the conjugated diene is greater than 20%.

[0050] In some embodiments, among the structural units derived from conjugated dienes, the mass content of the structural units derived from polyisoprene is 30-90%, and the mass content of the structural units derived from polybutadiene is 10-70%.

[0051] The copolymer containing cyclohexyl structure of the present invention is a multi-component copolymer substantially free of double bonds and containing cyclohexyl structure in the side chain. The multi-component copolymer containing cyclohexyl structure can be obtained by full hydrogenation of the multi-component copolymer.

[0052] In the copolymer of the present invention, the molar content of the structural unit containing unsaturated double bonds is not more than 5%, wherein the molar content of the structural unit containing unsaturated double bonds derived from conjugated dienes is not more than 2%; the molar content of the structural unit containing unsaturated double bonds derived from monovinyl aromatic hydrocarbons is not more than 5%. Preferably, the molar content of the structural unit containing unsaturated double bonds in the copolymer is 0, i.e., it does not contain unsaturated double bonds.

[0053] In the present invention, the unhydrogenated double bond content is expressed as molar content, which can be directly measured by nuclear magnetic resonance hydrogen spectrum, which is the same as the method for measuring the microstructure content.

[0054] In some embodiments, the number average molecular weight of the copolymer is 100,000-150,000 g / mol, wherein the number average molecular weight of segment C1 is 10,000-15,000 g / mol, the number average molecular weight of segment C2 is 10,000-15,000 g / mol, the number average molecular weight of segment A1 is 20,000-50,000 g / mol, the number average molecular weight of segment A2 is 10,000-15,000 g / mol, and the number average molecular weight of segment B is 30,000-50,000 g / mol.

[0055] According to the present invention, the unit of number average molecular weight is g / mol.

[0056] The second aspect of the present invention provides a method for preparing a copolymer containing a cyclohexyl structure, the preparation method comprising the following steps:

[0057] (1) in a non-polar hydrocarbon solvent, in the presence of a polarity regulator and an organic lithium initiator, subjecting a first monovinyl aromatic monomer to a first polymerization reaction to obtain an active polymerization section S1;

[0058] (2) subjecting the active polymerization section S1 to a second polymerization reaction with a first conjugated diene monomer and a second monovinyl aromatic monomer to obtain an active polymerization section S2;

[0059] (3) subjecting the active polymerization section S2 to a third polymerization reaction with a second conjugated diene monomer to obtain an active polymerization section S3;

[0060] (4) subjecting the active polymerization section S3 to a fourth polymerization reaction with a third conjugated diene monomer and a third monovinyl aromatic monomer to obtain an active polymerization section S4;

[0061] (5) subjecting the active polymerization section S4 to a fifth polymerization reaction with a fourth monovinyl aromatic monomer to obtain a copolymer precursor;

[0062] (6) In the presence of a hydrogenation catalyst, the copolymer precursor is subjected to a hydrogenation reaction to obtain a copolymer containing a cyclohexyl structure.

[0063] In step (1) of the present invention, the monovinyl aromatic monomer is polymerized to substantially complete conversion by a first polymerization reaction. In step (1), a non-polar hydrocarbon solvent is used. It should be apparent to those skilled in the art that the solvent should be in a liquid state under the polymerization reaction conditions of step (1), and will not participate in the polymerization reaction, nor will it react with the polymer obtained by the reaction, i.e., the solvent is inert. Such solvents are obvious to those of ordinary skill in the field of anionic polymerization and can be easily selected. Nevertheless, for the present invention, the non-polar hydrocarbon solvent is preferably benzene, toluene, ethylbenzene, xylene, pentane, hexane, heptane, octane, cyclohexane, xylene, raffinate or any combination of two or more of the foregoing solvents. For the polymerization of step (1), the amount of the non-polar hydrocarbon solvent is conventional, for example, the amount of the solvent can be controlled so that the monomer concentration is in the range of 5-30wt%, preferably 8-15wt%.

[0064] In some embodiments, the hydrogenation reaction hydrogenates at least 98% of the unsaturated double bonds of the structural units derived from the conjugated diene and at least 95% of the unsaturated double bonds of the structural units derived from the monovinylarene.

[0065] In some preferred embodiments, the hydrogenation reaction hydrogenates at least 99% of the unsaturated double bonds of the structural units derived from the conjugated diene and at least 98% of the unsaturated double bonds of the structural units derived from the monovinyl aromatic hydrocarbon.

[0066] In the present invention, the relevant structure content of the conjugated diene in the product can be determined by using nuclear magnetic hydrogen spectrum, and the degree of hydrogenation can also be determined by using nuclear magnetic hydrogen spectrum.

[0067] In the present invention, the higher the degree of hydrogenation of the unsaturated double bonds, the better, preferably 100% hydrogenation, because the polymer chain flexibility is poor due to the presence of double bonds, so that the thickening ability of the polymer is poor; in addition, due to the presence of double bonds, the hydrogen atoms conjugated with the double bonds in the polymer are easily attacked by oxygen and oxidized and cracked, so the high-temperature shear stability of the polymer is also poor; similarly, the presence of double bonds also makes the polymer relatively rigid, and its viscosity increases rapidly at low temperatures, and its low-temperature performance is poor.

[0068] According to the present invention, the monovinyl aromatic hydrocarbon refers to a compound in which one hydrogen on the aromatic ring is replaced by a vinyl group.

[0069] In some embodiments, the first monovinyl aromatic monomer, the second monovinyl aromatic monomer, the third monovinyl aromatic monomer and the fourth monovinyl aromatic monomer are each independently selected from the compound shown in Formula I,

[0070]

[0071] In Formula I, R7 is C6-C 20 substituted or unsubstituted aryl; preferably phenyl or phenyl substituted by one or more C1-C5 alkyl groups.

[0072] In the present invention, C6-C 20 Specific examples of the substituted or unsubstituted aryl groups may include, but are not limited to, phenyl, o-tolyl, m-tolyl, p-tolyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, o-tert-butylphenyl, m-tert-butylphenyl, p-tert-butylphenyl, p-dodecylphenyl, 2,4-di-n-butylphenyl, p-n-propylphenyl and 2,4-diethylphenyl.

[0073] In some embodiments, the monovinyl aromatic hydrocarbon is selected from one or more of styrene, 2-methylstyrene, 4-methylstyrene, 4-tert-butylstyrene, 4-methylstyrene, 3,5-diethylstyrene, 3,5-di-n-butylstyrene, 4-n-propylstyrene and 4-dodecylstyrene.

[0074] In some preferred embodiments, the monovinyl aromatic hydrocarbon is selected from one or more of styrene, 2-methylstyrene and 4-methylstyrene.

[0075] According to the present invention, the conjugated diene compound refers to an unsaturated chain hydrocarbon containing a conjugated double bond (i.e., -C=CC=C-) in the molecular structure, and can be various conjugated dienes commonly used in the art, without particular limitation. For example, the conjugated diene can be one or more conjugated dienes selected from C4-C8.

[0076] In some embodiments, the first conjugated diene monomer, the second conjugated diene monomer and the third conjugated diene monomer are each independently selected from one or more of butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene and 2,3-dimethylbutadiene; preferably butadiene and / or isoprene.

[0077] In some preferred embodiments, the mass ratio of isoprene to butadiene is 3-9:1-7.

[0078] In some preferred embodiments, in the second polymerization reaction, the third polymerization reaction and the fourth polymerization reaction, the molar content of the 1,2-structure formed is 20% or more, preferably 20-40%.

[0079] In the present invention, the molar content of 1,2-structure in the finally obtained copolymer is above 20%, and the copolymer is used as a lubricating oil viscosity modifier and has good low-temperature performance.

[0080] In some embodiments, the conditions of the first polymerization reaction include: reaction temperature of 20-100° C., preferably 40-80° C.; reaction pressure of 0.02-1 MPa, preferably 0.2-0.5 MPa; reaction time of 0.2-1 h, preferably 0.5-1 h.

[0081] In the preparation method of the present invention, after the polymerization reaction of step (1) is initiated, there is no particular requirement for the temperature of the subsequent steps (2), (3), (4) and (5), as long as the polymerization reaction can be maintained. In each polymerization step, the polymerization of the previous step is carried out until the polymerization is substantially completely converted, and then the next step is carried out.

[0082] In some embodiments, the conditions of the second polymerization reaction include: reaction temperature of 50-90°C, preferably 60-80°C; reaction pressure of 0.05-1MPa, preferably 0.1-0.5MPa; reaction time of 0.3-1h, preferably 0.5-0.7h.

[0083] In some embodiments, the conditions of the third polymerization reaction include: reaction temperature of 50-100° C., preferably 60-90° C.; reaction pressure of 0.05-1 MPa, preferably 0.1-0.5 MPa; reaction time of 0.3-1 h, preferably 0.5-0.7 h.

[0084] In some embodiments, the conditions of the fourth polymerization reaction include: reaction temperature of 50-100° C., preferably 60-90° C.; reaction pressure of 0.05-1 MPa, preferably 0.1-0.5 MPa; reaction time of 0.3-1 h, preferably 0.5-0.7 h.

[0085] In some embodiments, the conditions of the fifth polymerization reaction include: reaction temperature of 50-100° C., preferably 60-90° C.; reaction pressure of 0.05-1 MPa, preferably 0.1-0.5 MPa; reaction time of 0.3-1 h, preferably 0.5-0.7 h.

[0086] After the 4th polyreaction of step (4) of the present invention is completed, terminator can be used to terminate the polyreaction.Terminator used for this step is conventional for those skilled in the art.Usually usable terminator includes hydrogen, deionized water, alcohol, carbonic acid gas etc.Here, preferably hydrogen terminates.

[0087] In some embodiments, the conditions of the hydrogenation reaction include: reaction temperature of 80°C-160°C, preferably 80-150°C; hydrogen partial pressure of 0.5-6MPa, preferably 1-3MPa; reaction time of 0.5-6h, preferably 1-3h.

[0088] In step (1) of the present invention, various organic lithium initiators disclosed in the prior art can be used, preferably alkyl lithium initiators.

[0089] In some embodiments, the organic lithium initiator is selected from one or more of methyl lithium, ethyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-hexyl lithium, tert-octyl lithium and n-decyl lithium.

[0090] It is particularly preferred that the process of the present invention uses n-butyllithium as polymerization initiator.

[0091] For using a specific organic lithium initiator to synthesize a polymer with a specific molecular weight, those skilled in the art can determine the amount of the organic lithium initiator based on the disclosure of the prior art, and preferably the organic lithium initiator is added all at once.

[0092] Step (1) of the present invention is carried out in the presence of a polarity regulator. For the present invention, the polarity regulator used is a conventional reagent in the field of rubber synthesis, including oxygen-containing, nitrogen-containing, sulfur-containing or phosphorus-containing compounds or mixtures thereof.

[0093] In some embodiments, the polarity regulator is selected from one or more of diethyl ether, dibutyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl tetrahydrofurfuryl ether, dioxane, crown ether, triethylamine, tetramethylethylenediamine, hexamethylphosphoric triamide, potassium tert-butoxide, potassium tert-amyl alcohol, potassium lauryl alcohol, potassium alkylbenzene sulfonate and sodium alkylbenzene sulfonate, preferably ethyl tetrahydrofurfuryl ether is used as the polarity regulator.

[0094] In some embodiments, the molar ratio of the polarity regulator to the organic lithium initiator is 0.5-5:1, preferably 0.8-2:1.

[0095] In the method for preparing the block copolymer composition of the present invention, the temperature for initiating the polymerization of monovinylarene using an organic lithium initiator in step (1) can vary within a wide range. Generally, the initiation temperature is 20-100°C, preferably 40-80°C.

[0096] In some embodiments, the hydrogenation catalyst includes a carrier and an active component, an auxiliary agent and a modifier loaded on the carrier; the active component contains a Pt element, the modifier contains a halogen element, the auxiliary agent contains an IVA group element, an IVB group element, a rare earth metal element, and optionally, the auxiliary agent also contains an alkali metal element and / or an alkaline earth metal element; wherein the molar ratio of the IVA group element to the Pt element is 1-5:1.

[0097] For the specific composition and preparation method of the hydrogenation catalyst in the present invention, please refer to CN115364876A, which will not be described in detail here.

[0098] The third aspect of the present invention provides a copolymer containing a cyclohexyl structure obtained by the aforementioned preparation method.

[0099] The present invention introduces a random copolymer structure and a conjugated diene homopolymer segment into a monovinyl aromatic and conjugated diene block copolymer, adjusts the molecular weight and microstructure of different segments of the multi-polymer, and fully hydrogenates the unsaturated double bonds of the monovinyl aromatic and conjugated diene segments to obtain a new multi-polymer containing a cyclohexyl structure, which is used as a viscosity index improver, which not only maintains the anti-shear stability of hydrogenated polyisoprene, but also takes into account the good thickening effect of hydrogenated polybutadiene. At the same time, the introduction of the polycyclohexyl structure reduces the crystallization of hydrogenated polybutadiene and increases the compatibility with the lubricant base oil. When used in a lubricant oil composition, the thickening ability, shear stability, low-temperature performance and processing performance of the lubricant are significantly improved, especially for the preparation of engine oil, so that it has a lower pumping viscosity and low-temperature starting viscosity, and no crystallization or gel is generated. It is an excellent viscosity index improver and can be widely used in the field of high-level and large-span lubricants.

[0100] A fourth aspect of the present invention provides use of the aforementioned copolymer containing a cyclohexyl structure in lubricating oil.

[0101] A fifth aspect of the present invention provides a lubricating oil composition, comprising a base oil and a viscosity index improver, wherein the viscosity index improver contains the aforementioned copolymer containing a cyclohexyl structure.

[0102] In some embodiments, the content of the viscosity index improver is 0.5-2 wt % based on the total amount of the lubricating oil composition.

[0103] The present invention is described in detail below by way of examples, but the protection scope of the present invention is not limited to the following description.

[0104] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0105] In the following examples and comparative examples

[0106] (1) Polymer microstructure and degree of hydrogenation

[0107] It was determined by nuclear magnetic resonance hydrogen spectrum (1H-NMR). The 1H-NMR test was carried out on an AVANCEDRX400 MHz nuclear magnetic resonance instrument produced by BRUKER. The solvent used was deuterated chloroform. The sample was prepared into a solution with a concentration of 1-2 weight % at room temperature. Tetramethylsilane was used as an internal standard. The operating frequency of the nuclear magnetic resonance instrument was 400.13 MHz, the spectral width was 8012.82 Hz, the data point was 32 K, the pulse angle was 30°, the pulse width was 6 μs, the pulse delay was 5 s, and the sampling number was 64 times.

[0108] (2) Molecular weight and molecular weight distribution index (Mw / Mn)

[0109] The polymer samples were prepared into a solution with a mass concentration of 1 mg / mL, the injection volume was 100.00 μL, the flow rate was 1 mL / min, and the test temperature was 40.0°C.

[0110] The hydrogenation catalyst used in the following examples and comparative examples was prepared by the following preparation method, and the specific steps are as follows:

[0111] (1) impregnating a γ-alumina carrier with an equal volume of a cerium nitrate aqueous solution and drying at 120° C. for 8 hours to obtain an alumina carrier containing cerium;

[0112] (2) impregnating the alumina support containing cerium element obtained in step (1) with an aqueous solution containing potassium nitrate and magnesium nitrate in equal volumes, and drying at 120° C. for 8 hours to obtain a catalyst intermediate;

[0113] (3) The catalyst intermediate obtained in step (2) is impregnated with an equal volume of a hydrochloric acid-ethanol solution containing chloroplatinic acid, tin chloride and zirconium chloride (the volume ratio of hydrochloric acid to anhydrous ethanol is 1:2), dried at 120° C. for 8 hours, and then calcined at 600° C. for 6 hours to obtain a hydrogenation catalyst. The specific surface area of ​​the hydrogenation catalyst is 300 m 2 / g, and the average pore size is 17.6nm.

[0114] Example 1

[0115] (1) Preparation of multi-polymer hydrogenation precursor:

[0116] In a 5L stainless steel stirred tank, 2000g of cyclohexane, 120mg of ethyltetrahydrofurfuryl ether (ETE) and 25g of styrene (the first monovinyl aromatic monomer) were added, and 3.2mmol of n-butyl lithium initiator was added at 50°C, and polymerization was carried out for 30 minutes to obtain a styrene homopolymer; 102g of butadiene (the first conjugated diene monomer) and 60g of styrene (the second monovinyl aromatic monomer) were added to the reaction system, and the reaction was carried out for 40 minutes. After the random copolymerization of butadiene and styrene, 2 0.1 g of isoprene (the second conjugated diene monomer) was added and reacted for 40 minutes; 10.2 g of butadiene (the third conjugated diene monomer) and 60 g of styrene (the third monovinyl aromatic monomer) were added to the reaction system, and the random copolymerization of butadiene and styrene was carried out for 30 minutes; 24 g of styrene (the fourth monovinyl aromatic monomer) was then added and the reaction was continued for 30 minutes. After the polymerization reaction of the last added styrene was completely completed, 0.5 g of isopropanol (terminator) was added to terminate the reaction to obtain a polymer solution;

[0117] (2) Preparation of multi-polymers containing cyclohexyl structures by hydrogenation

[0118] In a 0.5L high-pressure stirred reactor, 200g of the polymer solution prepared in step (1) (the solvent is cyclohexane, the concentration is 20% by weight) and 1g of the hydrogenation catalyst prepared above are added to carry out a hydrogenation reaction. The hydrogenation reaction conditions include: temperature 150°C, hydrogen pressure 3MPa, reaction time 1h, and stirring speed 800rpm. After the reaction, the reaction product is filtered and separated to obtain a hydrogenated monovinyl aromatic polymer (polycyclohexyl vinyl fully saturated polymer) solution, and the solvent is removed to obtain a polycyclohexyl vinyl fully saturated polymer L1.

[0119] Example 2

[0120] (1) Preparation of multi-polymer hydrogenation precursor:

[0121] In a 5L stainless steel stirred tank, 2000g of cyclohexane, 120mg of ethyltetrahydrofurfuryl ether (ETE) and 38g of styrene (the first monovinyl aromatic monomer) were added, and 4.8mmol of n-butyl lithium initiator was added at 50°C, and polymerization was carried out for 30 minutes to obtain a styrene homopolymer; 60g of butadiene (the first conjugated diene monomer) and 25.4g of styrene (the second monovinyl aromatic monomer) were added to the reaction system, and the reaction was carried out for 40 minutes. After the random copolymerization of butadiene and styrene, 26 2g of isoprene (the second conjugated diene monomer) was reacted for 40 minutes; 60g of butadiene (the third conjugated diene monomer) and 25.4g of styrene (the third monovinyl aromatic monomer) were added to the reaction system, and the random copolymerization of butadiene and styrene was carried out for 30 minutes; 23.5g of styrene (the fourth monovinyl aromatic monomer) was then added, and the reaction was continued for 30 minutes. After the polymerization reaction of the last added styrene was completely completed, 0.5g of isopropanol (terminator) was added to terminate the reaction to obtain a polymer solution;

[0122] (2) Preparation of multi-polymers containing cyclohexyl structures by hydrogenation

[0123] In a 0.5L high-pressure stirred reactor, 200g of the polymer solution prepared in step (1) (the solvent is cyclohexane, the concentration is 20% by weight) and 1g of the hydrogenation catalyst prepared above are added to carry out a hydrogenation reaction. The hydrogenation reaction conditions include: temperature 150°C, hydrogen pressure 3MPa, reaction time 1h, and stirring speed 800rpm. After the reaction, the reaction product is filtered and separated to obtain a hydrogenated monovinyl aromatic polymer (polycyclohexyl vinyl fully saturated polymer) solution, and the solvent is removed to obtain a polycyclohexyl vinyl fully saturated polymer L2.

[0124] Example 3

[0125] (1) Preparation of multi-polymer hydrogenation precursor:

[0126] In a 5L stainless steel stirred tank, 2000g of cyclohexane, 100mg of ethyltetrahydrofurfuryl ether (ETE) and 14.5g of styrene (the first monovinyl aromatic monomer) were added, and 4.8mmol of n-butyl lithium initiator was added at 50°C, and polymerization was carried out for 30 minutes to obtain a styrene homopolymer; 90g of butadiene (the first conjugated diene monomer) and 12.8g of styrene (the second monovinyl aromatic monomer) were added to the reaction system, and the reaction was carried out for 40 minutes. After the random copolymerization of butadiene and styrene, the mixture was added. 218g of isoprene (the second conjugated diene monomer) was reacted for 40 minutes; 90g of butadiene (the third conjugated diene monomer) and 12.8g of styrene (the third monovinyl aromatic monomer) were added to the reaction system, and the random copolymerization of butadiene and styrene was carried out for 30 minutes; 15g of styrene (the fourth monovinyl aromatic monomer) was then added, and the reaction was continued for 30 minutes. After the polymerization reaction of the last added styrene was completely completed, 0.5g of isopropanol (terminator) was added to terminate the reaction to obtain a polymer solution;

[0127] (2) Hydrogenation to obtain a multi-polymer containing a cyclohexyl structure

[0128] In a 0.5L high-pressure stirred reactor, 200g of the polymer solution prepared in step (1) (the solvent is cyclohexane, the concentration is 20% by weight) and 1g of the hydrogenation catalyst prepared above are added to carry out a hydrogenation reaction. The hydrogenation reaction conditions include: temperature 150°C, hydrogen pressure 3MPa, reaction time 1h, and stirring speed 800rpm. After the reaction, the reaction product is filtered and separated to obtain a hydrogenated monovinyl aromatic polymer (polycyclohexyl vinyl fully saturated polymer) solution, and the solvent is removed to obtain a polycyclohexyl vinyl fully saturated polymer L3.

[0129] Example 4

[0130] (1) Preparation of multi-polymer hydrogenation precursor:

[0131] In a 5L stainless steel stirred tank, 2000g of cyclohexane, 100mg of ethyltetrahydrofurfuryl ether (ETE) and 26g of styrene (the first monovinyl aromatic monomer) were added, and 4.8mmol of n-butyl lithium initiator was added at 50°C, and polymerization was carried out for 30 minutes to obtain a styrene homopolymer; 142g of butadiene (the first conjugated diene monomer) and 60g of styrene (the second monovinyl aromatic monomer) were added to the reaction system, and the reaction was carried out for 40 minutes. After the random copolymerization of butadiene and styrene, 9 7g of isoprene (the second conjugated diene monomer) was added and reacted for 40 minutes; 71g of isoprene (the third conjugated diene monomer) and 60g of styrene (the third monovinyl aromatic monomer) were added to the reaction system, and the random copolymerization of isoprene and styrene was carried out for 30 minutes; 26g of styrene (the fourth monovinyl aromatic monomer) was added and the reaction was continued for 30 minutes. After the polymerization reaction of the last added styrene was completely completed, 0.5g of isopropanol (terminator) was added to terminate the reaction to obtain a polymer solution;

[0132] (2) Hydrogenation to obtain a multi-polymer containing a cyclohexyl structure

[0133] In a 0.5L high-pressure stirred reactor, 200g of the polymer solution prepared in step (1) (the solvent is cyclohexane, the concentration is 10% by weight) and 1g of the hydrogenation catalyst prepared above are added to carry out a hydrogenation reaction. The hydrogenation reaction conditions include: temperature 150°C, hydrogen pressure 3MPa, reaction time 1h, and stirring speed 800rpm. After the reaction, the reaction product is filtered and separated to obtain a hydrogenated monovinyl aromatic polymer (polycyclohexyl vinyl fully saturated polymer) solution, and the solvent is removed to obtain a polycyclohexyl vinyl fully saturated polymer L4.

[0134] Example 5

[0135] (1) Preparation of multi-polymer hydrogenation precursor:

[0136] In a 5L stainless steel stirred kettle, 2000g of cyclohexane, 142mg of tetrahydrofuran (THF) and 25g of styrene (the first monovinyl aromatic monomer) were added, and 3.2mmol of n-butyl lithium initiator was added at 50°C, and polymerization was carried out for 30 minutes to obtain a styrene homopolymer; 102g of butadiene (the first conjugated diene monomer) and 60g of styrene (the second monovinyl aromatic monomer) were added to the reaction system, and the reaction was carried out for 40 minutes. After the random copolymerization of butadiene and styrene, 20 1g of isoprene (the second conjugated diene monomer) was reacted for 40 minutes; 102g of butadiene (the third conjugated diene monomer) and 60g of styrene (the third monovinyl aromatic monomer) were added to the reaction system, and the random copolymerization of butadiene and styrene was allowed to proceed for 30 minutes; 24g of styrene (the fourth monovinyl aromatic monomer) was then added, and the reaction was continued for 30 minutes. After the polymerization reaction of the last added styrene was completely completed, 0.5g of isopropanol (terminator) was added to terminate the reaction to obtain a polymer solution;

[0137] (2) Preparation of multi-polymers containing cyclohexyl structures by hydrogenation

[0138] In a 0.5L high-pressure stirred reactor, 200g of the polymer solution prepared in step (1) (the solvent is cyclohexane, the concentration is 20% by weight) and 1g of the hydrogenation catalyst prepared above are added to carry out a hydrogenation reaction. The hydrogenation reaction conditions include: temperature 150°C, hydrogen pressure 3MPa, reaction time 1h, and stirring speed 800rpm. After the reaction, the reaction product is filtered and separated to obtain a hydrogenated monovinyl aromatic polymer (polycyclohexyl vinyl fully saturated polymer) solution, and the solvent is removed to obtain a polycyclohexyl vinyl fully saturated polymer L5.

[0139] Comparative Example 1

[0140] The multi-copolymer hydrogenation precursor was prepared according to step (1) of Example 1, except for step (2), which is as follows:

[0141] (2) Preparation of multi-polymers without cyclohexyl structure by hydrogenation

[0142] In a 0.5L high-pressure stirred reactor, 200g of the polymer solution prepared in step (1) (the solvent is cyclohexane, the concentration is 10% by weight) and nickel cyclohexane acid main catalyst; triisobutylaluminum co-catalyst, the molar ratio is 4:1, and a hydrogenation reaction is carried out. The hydrogenation reaction conditions include: temperature 80°C, hydrogen pressure 3MPa, reaction time 1h, and stirring speed 800rpm; after the reaction, the reaction product is separated to obtain a polymer solution of hydrogenated double bonds of conjugated dienes in the multi-polymer, and the solvent is removed to obtain a partially hydrogenated polymer D1.

[0143] Comparative Example 2

[0144] (1) Preparation of multi-polymer hydrogenation precursor:

[0145] In a 5L stainless steel stirred tank, 2000g of cyclohexane, 100mg of ethyltetrahydrofurfuryl ether (ETE) and 85g of styrene (the first monovinyl aromatic monomer) were added, and 3.2mmol of n-butyl lithium initiator was added at 50°C, and polymerization was carried out for 30 minutes to obtain a styrene homopolymer; 54g of butadiene (the first conjugated diene monomer) was added to the reaction system, and the reaction was carried out for 40 minutes, and after the butadiene copolymerization reaction; 202g of isoprene (the second conjugated diene monomer) was added, and the reaction was carried out for 40 minutes; 54g of butadiene (the third conjugated diene monomer) was added to the reaction system, and after the butadiene copolymerization reaction was carried out for 30 minutes; 85g of styrene (the second monovinyl aromatic monomer) was added, and the reaction was continued for 30 minutes. After the polymerization reaction of the last added styrene was completely completed, 0.5g of isopropanol (terminator) was added to terminate the reaction to obtain a polymer solution;

[0146] (2) Preparation of multi-polymers containing cyclohexyl structures by hydrogenation

[0147] In a 0.5L high-pressure stirred reactor, 200g of the polymer solution prepared in step (1) (the solvent is cyclohexane, the concentration is 20% by weight) and 1g of the hydrogenation catalyst prepared above are added to carry out a hydrogenation reaction. The hydrogenation reaction conditions include: temperature 150°C, hydrogen pressure 3MPa, reaction time 1h, and stirring speed 800rpm. After the reaction, the reaction product is filtered and separated to obtain a hydrogenated monovinyl aromatic polymer (polycyclohexyl vinyl fully saturated polymer) solution, and the solvent is removed to obtain a polycyclohexyl vinyl fully saturated polymer D2.

[0148] Table 1

[0149] project L1 L2 L3 L4 C1-A1-B-A2-C2(Mn) / 10,000 10.5 12.3 11.4 15.0 (C1+C2) weight% 10.2 9.8 12.0 10.8 A1 weight% 23.8 17.7 21.5 27.1 A2 weight% 23.9 17.8 21.5 27.1 B weight% 42.1 54.7 45.0 35.0 C1(Mn) / 10,000 1.3 1.0 1.8 1.9 A1(Mn) / 10,000 1.7 2.6 2.6 3.5 B(Mn) / ten thousand 4.1 4.9 3.1 4.5 A2(Mn) / 10,000 1.9 2.5 2.5 3.6 C2(Mn) / 10,000 1.5 1.3 1.4 1.5 1,2PB / weight% 20.6 25.3 30.6 34.1 3,4IP / wt% 22.6 30.9 36.3 39.6 Benzene ring hydrogenation degree % 99.8 99.2 99.3 99.5 Degree of hydrogenation of conjugated diene segment 99.2 98.9 99.1 99.6

[0150] Table 1 (continued)

[0151] project L5 D1 D2 C1-A1-B-A2-C2(Mn) / 10,000 10.5 10.5 10.5 (C1+C2) weight% 10.2 10.2 35.4 A1 weight% 12.5 12.5 0 A2 weight% 12.6 12.6 0 B weight% 42.0 42.0 42.0 EB weight% 22.6 22.6 22.6 C1(Mn) / 10,000 1.3 1.3 1.3 A1(Mn) / 10,000 1.7 1.7 1.7 B(Mn) / ten thousand 4.0 4.0 4.0 A2(Mn) / 10,000 2.0 1.9 2.0 C2(Mn) / 10,000 1.6 1.5 1.6 1,2PB / weight% 21.2 20.6 20.5 3,4IP / wt% 22.3 22.6 15.3 Benzene ring hydrogenation degree % 99.2 3.4 99.2 Degree of hydrogenation of conjugated diene segment 98.9 98.5 98.9

[0152] Test Case

[0153] The viscosity index improvers L1-L5, D1 and D2 were mixed with base oil (150SN lubricant purchased from Yanshan Petrochemical Company) at a weight ratio of 1:100 to obtain lubricants V1-V4, R5 and R6. The obtained lubricants were tested for performance in the following manner. The results are shown in Table 2-4:

[0154] Kinematic viscosity refers to the ratio of the absolute viscosity of the lubricating oil to the density of the lubricating oil at the same temperature, in mm 2 / s, the kinematic viscosity of the solution was tested using a rotational rheometer (Thermo Scientific HAAKE RheoStress 6000) according to GB265-88, and the test temperature was 100°C;

[0155] The viscosity index refers to the viscosity index, which indicates the degree to which the viscosity of the lubricating oil changes with temperature. VI = [(LU) / (LH)] × 100. It is calculated by testing the kinematic viscosity of the solution using a rotational rheometer (Thermo Scientific HAAKE RheoStress 6000);

[0156] Thickening capacity refers to the difference between the viscosity of a base oil with a viscosity index improver added and that of a base oil without a viscosity index improver added, and is determined by measuring the difference in the kinematic viscosity of the lubricating oil at 100°C.

[0157] Shear stability index (SSI) refers to the ability of a polymer to increase viscosity under shear conditions; SSI = 100% × (Vb-Va) / (Vb-V0);

[0158] Wherein, Vb is the viscosity of the lubricating oil before shearing, Va is the viscosity of the lubricating oil after shearing, and V0 is the viscosity of the base oil.

[0159] High temperature and high shear viscosity refers to the apparent viscosity of lubricating oil measured under high temperature and high shear rate conditions;

[0160] Pour point refers to the lowest temperature at which lubricating oil can flow during the process of rising temperature, expressed in °C; it is determined according to the method of GB / T3535.

[0161] Table 2 High temperature viscosity enhancement effect

[0162]

[0163] Note: “—” means the base oil itself has no thickening ability, and this item is 0.

[0164] It can be seen from the data in Table 2 that the viscosity index of the lubricating oil prepared with the viscosity index improver in the embodiment of the present invention is better than that of the comparative sample prepared in the comparative example, indicating that the viscosity index improver in the embodiment of the present invention has a strong thickening ability for the lubricating oil base oil.

[0165] Table 3 High temperature shear resistance

[0166]

[0167]

[0168] It can be seen from the data in Table 3 that the shear stability index SSI and high temperature high shear viscosity of the lubricating oil prepared by the viscosity index improver of the embodiment of the present invention are better than those of the comparative sample prepared by the comparative example, indicating that the lubricating oil prepared by the embodiment of the present invention has good shear stability. However, the shear stability index SSI of the comparative sample is higher, and the shear stability is not as good as that of the present invention.

[0169] The partially hydrogenated polymer D1 obtained in Comparative Example 1 is a conjugated diene double bond hydrogenation product obtained by partially hydrogenating a multi-polymer. As a lubricating oil viscosity modifier, its high temperature shear resistance is worse than that of L1-L5.

[0170] The copolymer D2 obtained in Comparative Example 2 is a hydrogenated copolymer precursor of a homopolymer. As a lubricating oil viscosity modifier, its high temperature shear resistance is worse than that of L1-L5.

[0171] Table 4 Low temperature fluidity

[0172]

[0173] It can be seen from the data in Table 4 that the lubricating oil prepared by the viscosity index improver of the present invention has a lower low-temperature viscosity, which is conducive to the use of the lubricating oil in a low-temperature environment and has better low-temperature pumping performance. However, the low-temperature pumping performance of the comparative sample is poor.

[0174] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A copolymer containing a cyclohexyl structure, characterized in that: The copolymer contains at least three block structures and at least two random gradient structures, and contains a cyclohexyl structure; the general formula of the copolymer is C1-A1-B-A2-C2, wherein the C1 segment and the C2 segment are block structures, and the C1 segment and the C2 segment each independently include the structural unit shown in formula (1); the A1 segment and the A2 segment are random gradient structures, and the A1 segment and the A2 segment each independently include the structural unit shown in formula (1) and the structural unit shown in formula (2); the B segment is a homopolymer block structure; the B segment includes the structural unit shown in formula (2); Wherein, R1 and R2 are each independently H or a substituted or unsubstituted cyclohexyl group, and R1 and R2 are not H at the same time; R3, R4, R5 and R6 are each independently H or a C1-C4 alkyl group, and R3, R4, R5 and R6 are not H at the same time.

2. The copolymer according to claim 1, wherein In the copolymer, based on the total mass of the copolymer, the mass content of the structural unit represented by formula (1) is 5-35%; the mass content of the structural unit represented by formula (2) is 65-95%.

3. The copolymer according to claim 1 or 2, wherein The C1 segment and the C2 segment are each independently derived from a block structure of monovinyl aromatic hydrocarbons and obtained by hydrogenation; And / or, the A1 segment and the A2 segment are independently derived from random gradient structures of monovinyl aromatic hydrocarbons and conjugated dienes through hydrogenation; And / or, the B segment is derived from a homopolymer block structure of a conjugated diene and is obtained by hydrogenation; Preferably, the monovinyl aromatic hydrocarbon is a compound represented by formula I, In Formula I, R7 is C6-C 20 a substituted or unsubstituted aryl group; Preferably, the conjugated diene is selected from one or more of butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene and 2,3-dimethylbutadiene; more preferably, the conjugated diene is butadiene and / or isoprene.

4. The copolymer according to claim 3, wherein In the copolymer, the molar content of 1,2-structure in the structural units derived from conjugated dienes is greater than 20%; And / or, in the copolymer, among the structural units derived from conjugated dienes, the mass content of the structural units derived from polyisoprene is 30-90%, and the mass content of the structural units derived from polybutadiene is 10-70%; and / or, in the copolymer, at least 99% of the unsaturated double bonds of the structural units derived from the conjugated diene are hydrogenated; The unsaturated double bonds of the structural units derived from monovinylarene are at least 98% hydrogenated.

5. The copolymer according to any one of claims 1 to 4, wherein The number average molecular weight of the copolymer is 100,000-150,000 g / mol, wherein the number average molecular weight of segment C1 is 10,000-15,000 g / mol, the number average molecular weight of segment C2 is 10,000-15,000 g / mol, the number average molecular weight of segment A1 is 20,000-50,000 g / mol, the number average molecular weight of segment A2 is 10,000-15,000 g / mol, and the number average molecular weight of segment B is 30,000-50,000 g / mol.

6. A method for preparing a copolymer containing a cyclohexyl structure, characterized in that: The preparation method comprises the following steps: (1) in a non-polar hydrocarbon solvent, in the presence of a polarity regulator and an organic lithium initiator, subjecting a first monovinyl aromatic monomer to a first polymerization reaction to obtain an active polymerization section S1; (2) subjecting the active polymerization section S1 to a second polymerization reaction with a first conjugated diene monomer and a second monovinyl aromatic monomer to obtain an active polymerization section S2; (3) subjecting the active polymerization section S2 to a third polymerization reaction with a second conjugated diene monomer to obtain an active polymerization section S3; (4) subjecting the active polymerization section S3 to a fourth polymerization reaction with a third conjugated diene monomer and a third monovinyl aromatic monomer to obtain an active polymerization section S4; (5) subjecting the active polymerization section S4 to a fifth polymerization reaction with a fourth monovinyl aromatic monomer to obtain a copolymer precursor; (6) In the presence of a hydrogenation catalyst, the copolymer precursor is subjected to a hydrogenation reaction to obtain a copolymer containing a cyclohexyl structure.

7. The preparation method according to claim 6, wherein: The hydrogenation reaction hydrogenates at least 98% of the unsaturated double bonds of the structural units derived from the conjugated diene and at least 95% of the unsaturated double bonds of the structural units derived from the monovinyl aromatic hydrocarbon; Preferably, the hydrogenation reaction causes at least 99% of the unsaturated double bonds of the structural units derived from the conjugated diene to be hydrogenated; The unsaturated double bonds of the structural units derived from monovinylarene are at least 98% hydrogenated.

8. The preparation method according to claim 6 or 7, wherein: The first monovinyl aromatic monomer, the second monovinyl aromatic monomer, the third monovinyl aromatic monomer and the fourth monovinyl aromatic monomer are each independently selected from the compound shown in Formula I, In Formula I, R7 is C6-C 20 A substituted or unsubstituted aryl group.

9. The preparation method according to any one of claims 6 to 8, wherein: The first conjugated diene monomer, the second conjugated diene monomer and the third conjugated diene monomer are each independently selected from one or more of butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene and 2,3-dimethylbutadiene; preferably selected from butadiene and / or isoprene; Preferably, the mass ratio of isoprene to butadiene is 3-9:1-7; Preferably, in the second polymerization reaction, the third polymerization reaction and the fourth polymerization reaction, the molar content of the 1,2-structure formed is 20% or more, preferably 20-40%.

10. The preparation method according to any one of claims 6 to 9, wherein: The conditions of the first polymerization reaction include: reaction temperature of 20-100°C, reaction pressure of 0.02-1MPa, and reaction time of 0.2-1h; And / or, the conditions of the second polymerization reaction include: reaction temperature of 50-100° C., reaction pressure of 0.05-1 MPa, and reaction time of 0.3-1 h; And / or, the conditions of the third polymerization reaction include: reaction temperature of 50-100° C., reaction pressure of 0.05-1 MPa, and reaction time of 0.3-1 h; And / or, the conditions of the fourth polymerization reaction include: reaction temperature of 50-100° C., reaction pressure of 0.05-1 MPa, and reaction time of 0.3-1 h; And / or, the conditions of the fifth polymerization reaction include: reaction temperature of 50-100° C., reaction pressure of 0.05-1 MPa, and reaction time of 0.3-1 h; And / or, the conditions of the hydrogenation reaction include: reaction temperature of 80°C-160°C, hydrogen partial pressure of 0.5-6MPa, and reaction time of 0.5-6h.

11. The preparation method according to any one of claims 6 to 10, wherein: The organic lithium initiator is selected from one or more of methyl lithium, ethyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-hexyl lithium, tert-octyl lithium and n-decyl lithium; and / or, the polarity regulator is selected from one or more of diethyl ether, dibutyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl tetrahydrofurfuryl ether, dioxane, crown ether, triethylamine, tetramethylethylenediamine, hexamethylphosphoric triamide, potassium tert-butoxide, potassium tert-amyloxide, potassium lauryloxide, potassium alkylbenzene sulfonate and sodium alkylbenzene sulfonate; Preferably, the molar ratio of the polarity regulator to the organic lithium initiator is 0.5-5:1, preferably 0.8-2:

1.

12. The preparation method according to any one of claims 6 to 11, wherein: The hydrogenation catalyst comprises a carrier and an active component, an auxiliary agent and a modifier loaded on the carrier; the active component contains a Pt element, the modifier contains a halogen element, the auxiliary agent contains an IVA group element, an IVB group element, and a rare earth metal element, and optionally, the auxiliary agent further contains an alkali metal element and / or an alkaline earth metal element; wherein the molar ratio of the IVA group element to the Pt element is 1-5:

1.

13. A copolymer containing a cyclohexyl structure obtained by the preparation method according to any one of claims 6 to 12.

14. Use of the copolymer containing cyclohexyl structure according to any one of claims 1 to 5 and 13 in lubricating oil.

15. A lubricating oil composition, characterized in that: The lubricating oil composition comprises a base oil and a viscosity index improver, wherein the viscosity index improver comprises the copolymer containing a cyclohexyl structure as claimed in any one of claims 1 to 5 and 13; Preferably, the content of the viscosity index improver is 0.5-2 wt % based on the total weight of the lubricating oil composition.

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