Monovinylarene-conjugated diene polymer as well as preparation method and application thereof

Abstract

The invention relates to the field of polymers, and discloses a monovinylarene-conjugated diene polymer as well as a preparation method and application thereof. The polymer contains a first polymeric chain, a second polymeric chain and a structure formed by coupling the first polymeric chain and the second polymeric chain, the number-average molecular weight of the first polymeric chain is 70000-180000 g / mol, the number-average molecular weight of the second polymeric chain is 40000-120000 g / mol, and the conjugated diene structural unit mass in the first polymeric chain is used as a reference, and the conjugated diene structural unit mass in the second polymeric chain is 1-10% of the conjugated diene structural unit mass in the first polymeric chain. On the basis of the mass of the conjugated diene structural unit in the first polymer chain, the content of conjugated diene side group structure is 10-30%, and on the basis of the mass of the conjugated diene structural unit in the second polymer chain, the content of conjugated diene side group is 50-65%. When the monovinylarene-conjugated diene polymer is used as rubber to prepare vulcanized rubber, the monovinylarene-conjugated diene polymer has excellent wear resistance, high wet skid resistance and low rolling resistance.

Description

Technical Field

[0001] The present invention relates to the field of polymers, and in particular, to a mono-vinyl aromatic-conjugated diene polymer and a preparation method and application thereof. Background Art

[0002] Solution-polymerized styrene-butadiene rubber (SSBR, also known as solution-polymerized styrene-butadiene rubber) is a copolymer rubber prepared by anionic solution polymerization of butadiene and styrene monomers with an alkyl lithium initiator in a hydrocarbon solvent.

[0003] Since SSBR has excellent abrasion resistance, groove cracking resistance, good grip on wet roads, heat resistance, and flex resistance after long-term exposure at high temperatures, and also has the characteristics of low heat generation during mixing in a Banbury mixer, small die swell ratio, and high filling amount, its application proportion in tire products is increasing.

[0004] Utilizing the abrasion resistance, excellent dynamic performance, and low-temperature characteristics of SSBR, it can also be used to manufacture large tires, snow tires, etc.

[0005] From the perspectives of abrasion resistance, tensile strength, cure flatness, flex resistance, and heat resistance, SSBR is suitable for manufacturing conveyor belts, especially heat-resistant conveyor belts.

[0006] SSBR also has advantages such as good electrical insulation performance, excellent color, low ash content, and low content of non-rubber components.

[0007] From the perspective of the balance between processing performance and physical and mechanical properties, SSBR is a rubber variety with a variety of comprehensive properties.

[0008] In view of the excellent properties of solution-polymerized styrene-butadiene rubber, there has been much research in this field. In CN102344529A, a method of preparing solution-polymerized styrene-butadiene rubber by adding an anionic initiator multiple times and coupling multiple times is adopted. This method can improve the distribution coefficient of the polymer, which is beneficial to processing performance, but there is no innovative change in the microstructure, and the process of this method is relatively complex, inconvenient to operate, and has poor test repeatability. CN1432586A discloses a solution-polymerized styrene-butadiene rubber containing a high molecular weight, but the content of the high molecular weight part is 10-40% by weight, which is too high and not conducive to the processing of later products. Summary of the Invention

[0009] The object of the present invention is to provide a mono-vinyl aromatic-conjugated diene polymer with a diversified structure and a preparation method and application thereof.

[0010] The mono-vinyl aromatic-conjugated diene polymer of the present invention realizes the coexistence of two structures with different benzene contents and different side group contents in the polymer through ingenious structural design. Therefore, when it is used as a rubber to prepare vulcanized rubber, it has excellent wear resistance, high wet skid resistance and low rolling resistance, and is a preferred choice for the tread rubber or tread compound of green tires with silica as the main reinforcing agent. The tire has excellent fuel economy, wet grip performance and wear resistance at the same time.

[0011] To achieve the above object, on the one hand, the present invention provides a mono-vinyl aromatic-conjugated diene polymer, wherein the polymer contains a first mono-vinyl aromatic-conjugated diene polymerization chain, a second mono-vinyl aromatic-conjugated diene polymerization chain, and a structure formed by coupling the first mono-vinyl aromatic-conjugated diene polymerization chain and the second mono-vinyl aromatic-conjugated diene polymerization chain. Among them, the number average molecular weight of the first mono-vinyl aromatic-conjugated diene polymerization chain is 70,000-180,000 g / mol, the number average molecular weight of the second mono-vinyl aromatic-conjugated diene polymerization chain is 40,000-120,000 g / mol. Based on the mass of the conjugated diene structural unit in the first mono-vinyl aromatic-conjugated diene polymerization chain, the content of the conjugated diene side group structure in the first mono-vinyl aromatic-conjugated diene polymerization chain is 10-30%, and based on the mass of the conjugated diene structural unit in the second mono-vinyl aromatic-conjugated diene polymerization chain, the content of the conjugated diene side group in the second mono-vinyl aromatic-conjugated diene polymerization chain is 50-65%.

[0012] Preferably, based on the mass of the first mono-vinyl aromatic-conjugated diene polymerization chain, the mass content of the mono-vinyl aromatic structural unit in the first mono-vinyl aromatic-conjugated diene polymerization chain is 25-45%, preferably 30-40%.

[0013] Preferably, based on the mass of the mono-vinyl aromatic-conjugated diene polymer, the mass content of the first mono-vinyl aromatic-conjugated diene polymerization chain is 10-25%, and the mass content of the second mono-vinyl aromatic-conjugated diene polymerization chain is 75-90%.

[0014] Preferably, the coupling efficiency is 40-80% by weight, preferably 50-65% by weight.

[0015] Preferably, based on the mass of the second mono-vinyl aromatic-conjugated diene polymerization chain, the mass content of the mono-vinyl aromatic in the second mono-vinyl aromatic-conjugated diene polymerization chain is 5-25%, preferably 10-20%.

[0016] Preferably, the coupling structural unit is at least one selected from silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, epoxidized castor oil, divinylbenzene, methoxysilane, dibromosilane, and dichlorosilane, preferably from silicon tetrachloride.

[0017] Preferably, the conjugated diene is at least one selected from butadiene, isoprene, 1,3 - pentadiene, 1,3 - hexadiene, and 2,3 - dimethylbutadiene.

[0018] Preferably, the conjugated diene is butadiene.

[0019] Preferably, the mono - vinyl aromatic hydrocarbon is at least one selected from styrene, vinyltoluene, α - methylstyrene, 4 - tert - butylstyrene, 4 - methylstyrene, 3,5 - diethylstyrene, 3,5 - di - n - butylstyrene, 4 - n - propylstyrene, and 4 - dodecylstyrene.

[0020] Preferably, the mono - vinyl aromatic hydrocarbon is styrene.

[0021] According to the second aspect of the present invention, there is provided a method for preparing a mono - vinyl aromatic hydrocarbon - conjugated diene polymer, wherein the method comprises the following steps:

[0022] 1) A step of carrying out a first polymerization reaction on a material A containing a mono - vinyl aromatic hydrocarbon monomer, a conjugated diene monomer, and a non - polar solvent in the presence of an anionic initiator a;

[0023] 2) A step of carrying out a second polymerization reaction on the first polymerization product obtained in step 1) and a material B containing a mono - vinyl aromatic hydrocarbon monomer, a conjugated diene monomer, a polar regulator, and a non - polar solvent in the presence of an anionic initiator b;

[0024] 3) A step of carrying out a coupling reaction on the second polymerization product obtained in step 2) in the presence of a coupling agent.

[0025] Preferably, the material A further contains a polar regulator, and the amount of the polar regulator in the material A is 50 ppm or less, preferably 10 - 40 ppm.

[0026] Preferably, the amount of the polar regulator in the material B is 100 - 600 ppm, preferably 200 - 400 ppm.

[0027] Preferably, based on the total mass of the polymerization monomers, the mass content of the polymerization monomers in the material A is 10 - 25%, and the mass content of the polymerization monomers in the material B is 75 - 90%.

[0028] Preferably, the mass percentage of the mono - vinyl aromatic hydrocarbon monomer in the material A is 25 - 45%, preferably 30 - 40%.

[0029] Preferably, the mass percentage content of the monovinyl aromatic monomer in the material B is 5-25%, preferably 10-20%. Preferably, the molar ratio of the anionic initiator a to the anionic initiator b is 1:1.4-26.

[0030] Preferably, the conjugated diene is selected from at least one of butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, and 2,3-dimethylbutadiene.

[0031] Preferably, the conjugated diene is butadiene.

[0032] Preferably, the monovinyl aromatic is selected from at least one of styrene, vinyltoluene, α-methylstyrene, 4-tert-butylstyrene, 4-methylstyrene, 3,5-diethylstyrene, 3,5-di-n-butylstyrene, 4-n-propylstyrene, and 4-dodecylstyrene.

[0033] Preferably, the monovinyl aromatic is styrene.

[0034] Preferably, the polar regulator is selected from at least one of diethyl ether, dibutyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofurfuryl ether, dioxane, crown ether, triethylamine, tetramethylethylenediamine, hexamethylphosphoric triamide, potassium tert-butoxide, potassium tert-pentoxide, potassium laurate, potassium alkylbenzenesulfonate, and sodium alkylbenzenesulfonate, preferably tetrahydrofurfuryl ether.

[0035] Preferably, the anionic initiator a and the anionic initiator b are each independently a compound having an RLi structure, where R is a straight-chain or branched-chain alkyl group of C1-C 10 of the straight-chain or branched-chain alkyl group.

[0036] Preferably, the R is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, and n-decyl.

[0037] Preferably, the coupling agent is selected from at least one of silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, epoxidized castor oil, divinylbenzene, methoxysilane, dibromosilane, and dichlorosilane, preferably silicon tetrachloride.

[0038] According to the third aspect of the present invention, there is provided a monovinyl aromatic-conjugated diene polymer prepared by the method described in the second aspect of the present invention.

[0039] According to the fourth aspect of the present invention, there is provided an application of the monovinyl aromatic-conjugated diene polymer described in the first aspect and the third aspect of the present invention in a rubber compound for a tire tread.

[0040] Through the above technical solutions, the present invention can provide a single vinyl aromatic-conjugated diene polymer with a diversified structure, and its preparation method and application. The single vinyl aromatic-conjugated diene polymer of the present invention realizes the coexistence of two structures with different benzene contents and different side group contents in the polymer through a clever structural design. Therefore, when it is used as a rubber to prepare vulcanized rubber, it has excellent wear resistance, high wet skid resistance and low rolling resistance, and is a preferred choice for the tread rubber or tread compound of green tires with silica as the main reinforcing agent. The tire has excellent fuel economy, wet grip performance and wear resistance at the same time. Detailed Embodiments

[0041] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. 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, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0042] In the present invention, the term "single vinyl aromatic" refers to a compound formed by replacing one hydrogen on the aromatic ring with a vinyl group. For example, the single vinyl aromatic can be at least one selected from the compounds shown in Formula II.

[0043]

[0044] In Formula II, R1 is a substituted or unsubstituted aryl group having 6 to C 20 The specific examples of the substituted or unsubstituted aryl group having 6 to C 20 can 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, 3,5-diethylphenyl, 2,4-di-n-butylphenyl, 3,5-di-n-butylphenyl, p-n-propylphenyl and 2,4-diethylphenyl.

[0045] Preferably, the single vinyl aromatic is at least one selected from styrene, vinyltoluene, α-methylstyrene, 4-tert-butylstyrene, 4-methylstyrene, 3,5-diethylstyrene, 3,5-di-n-butylstyrene, 4-n-propylstyrene and 4-dodecylstyrene.

[0046] More preferably, the single vinyl aromatic is at least one selected from styrene, 2-methylstyrene and 4-methylstyrene.

[0047] Further preferably, the single vinyl aromatic is styrene.

[0048] In the present invention, the term "conjugated diene" refers to an unsaturated chain hydrocarbon containing conjugated double bonds (i.e., -C=C-C=C-) in its molecular structure, and can be various conjugated dienes commonly used in the art without particular limitation. For example, the conjugated diene is at least one selected from conjugated dienes having 4 to 8 carbon atoms.

[0049] Preferably, the conjugated diene is at least one selected from butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, and 2,3-dimethylbutadiene.

[0050] More preferably, the conjugated diene is butadiene and / or isoprene.

[0051] Even more preferably, the conjugated diene is butadiene.

[0052] In the present invention, the "coupling efficiency" refers to the weight percentage of the number of coupled molecular chains in the total number of molecular chains, that is, the coupling efficiency refers to the content of the polymer formed by coupling (i.e., the coupling component) based on the total amount of the monovinylarene-conjugated diene polymer, and the balance is the content of the uncoupled monovinylarene-conjugated diene polymer (i.e., the uncoupled component).

[0053] According to the first aspect of the present invention, there is provided a monovinylarene-conjugated diene polymer, wherein the polymer contains a first monovinylarene-conjugated diene polymer chain, a second monovinylarene-conjugated diene polymer chain, and a structure formed by coupling the first monovinylarene-conjugated diene polymer chain and the second monovinylarene-conjugated diene polymer chain. The number average molecular weight of the first monovinylarene-conjugated diene polymer chain is 70,000 - 180,000 g / mol, the number average molecular weight of the second monovinylarene-conjugated diene polymer chain is 40,000 - 120,000 g / mol. Based on the mass of the conjugated diene structural unit in the first monovinylarene-conjugated diene polymer chain, the content of the conjugated diene side group structure in the first monovinylarene-conjugated diene polymer chain is 10 - 30%, and based on the mass of the conjugated diene structural unit in the second monovinylarene-conjugated diene polymer chain, the content of the conjugated diene side group in the second monovinylarene-conjugated diene polymer chain is 50 - 65%.

[0054] According to the present invention, the vinyl aromatic-conjugated diene polymer contains a first vinyl aromatic-conjugated diene polymer chain, a second vinyl aromatic-conjugated diene polymer chain, and a structure formed by coupling the first vinyl aromatic-conjugated diene polymer chain and the second vinyl aromatic-conjugated diene polymer chain; preferably, the vinyl aromatic-conjugated diene polymer is a structure formed by coupling the first vinyl aromatic-conjugated diene polymer chain, the second vinyl aromatic-conjugated diene polymer chain, and the first vinyl aromatic-conjugated diene polymer chain - the second vinyl aromatic-conjugated diene polymer chain.

[0055] According to the present invention, the first vinyl aromatic-conjugated diene polymer chain is a polymer chain formed by copolymerizing a vinyl aromatic and a conjugated diene in the presence of the following anionic initiator a.

[0056] In the present invention, the number average molecular weight of the first vinyl aromatic-conjugated diene polymer chain is 70,000 - 180,000 g / mol; preferably, the number average molecular weight of the first vinyl aromatic-conjugated diene polymer chain is 75,000 - 160,000 g / mol; more preferably, the number average molecular weight of the first vinyl aromatic-conjugated diene polymer chain is 78,000 - 150,000 g / mol.

[0057] In the present invention, the number average molecular weight of the second vinyl aromatic-conjugated diene polymer chain is 40,000 - 120,000 g / mol; preferably, the number average molecular weight of the second vinyl aromatic-conjugated diene polymer chain is 45,000 - 110,000 g / mol; more preferably, the number average molecular weight of the second vinyl aromatic-conjugated diene polymer chain is 50,000 - 100,000 g / mol.

[0058] In the present invention, the first vinyl aromatic-conjugated diene polymer chain includes the "first vinyl aromatic-conjugated diene polymer chain" in the "first vinyl aromatic-conjugated diene polymer chain" and the "first vinyl aromatic-conjugated diene polymer chain - second vinyl aromatic-conjugated diene polymer chain".

[0059] In the present invention, the second vinyl aromatic-conjugated diene polymer chain includes the "second vinyl aromatic-conjugated diene polymer chain" in the "second vinyl aromatic-conjugated diene polymer chain" and the "first vinyl aromatic-conjugated diene polymer chain - second vinyl aromatic-conjugated diene polymer chain".

[0060] In the present invention, based on the mass of the conjugated diene structural units in the first mono-vinyl aromatic-conjugated diene polymer chain, the content of the conjugated diene side group structure in the first mono-vinyl aromatic-conjugated diene polymer chain is 10-30%; preferably, based on the mass of the conjugated diene structural units in the first mono-vinyl aromatic-conjugated diene polymer chain, the content of the conjugated diene side group structure in the first mono-vinyl aromatic-conjugated diene polymer chain is 15-30%.

[0061] In the present invention, based on the mass of the conjugated diene structural units in the second mono-vinyl aromatic-conjugated diene polymer chain, the content of the conjugated diene side groups in the second mono-vinyl aromatic-conjugated diene polymer chain is 50-65%; preferably, based on the mass of the conjugated diene structural units in the second mono-vinyl aromatic-conjugated diene polymer chain, the content of the conjugated diene side groups in the second mono-vinyl aromatic-conjugated diene polymer chain is 50-60%.

[0062] According to the present invention, for the purpose that the target product has excellent dynamic properties, preferably, based on the mass of the mono-vinyl aromatic-conjugated diene polymer, the mass content of the first mono-vinyl aromatic-conjugated diene polymer chain is 10-25%, and the mass content of the second mono-vinyl aromatic-conjugated diene polymer chain is 75-90%.

[0063] Specific examples of the mass content of the first mono-vinyl aromatic-conjugated diene polymer chain based on the mass of the mono-vinyl aromatic-conjugated diene polymer, for example, can include: 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., and the ranges formed by any two of the above.

[0064] Specific examples of the mass content of the second mono-vinyl aromatic-conjugated diene polymer chain based on the mass of the mono-vinyl aromatic-conjugated diene polymer, for example, can include: 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, etc., and the ranges formed by any two of the above.

[0065] According to the present invention, preferably, based on the mass of the first mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the mono-vinyl aromatic structural units in the first mono-vinyl aromatic-conjugated diene polymer chain is 25-45%; more preferably, based on the mass of the first mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the mono-vinyl aromatic structural units in the first mono-vinyl aromatic-conjugated diene polymer chain is 30-40%.

[0066] According to the present invention, preferably, based on the mass of the first mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the conjugated diene structural unit in the first mono-vinyl aromatic-conjugated diene polymer chain is 55-75%; more preferably, based on the mass of the first mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the conjugated diene structural unit in the first mono-vinyl aromatic-conjugated diene polymer chain is 60-70%.

[0067] According to the present invention, preferably, based on the mass of the second mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the mono-vinyl aromatic in the second mono-vinyl aromatic-conjugated diene polymer chain is 5-25%; more preferably, based on the mass of the second mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the mono-vinyl aromatic in the second mono-vinyl aromatic-conjugated diene polymer chain is 10-20%.

[0068] According to the present invention, preferably, based on the mass of the second mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the conjugated diene in the second mono-vinyl aromatic-conjugated diene polymer chain is 75-95%; more preferably, based on the mass of the second mono-vinyl aromatic-conjugated diene polymer chain, the mass content of the conjugated diene in the second mono-vinyl aromatic-conjugated diene polymer chain is 80-90%.

[0069] In the present invention, the coupling is carried out by a coupling agent, and the coupling unit from the coupling agent is from at least one of silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, epoxidized castor oil, divinylbenzene, methoxysilane, dibromosilane and dichlorosilane, preferably from silicon tetrachloride.

[0070] Preferably, the efficiency of the coupling is 40-80% by weight; more preferably, the efficiency of the coupling is 50-65% by weight.

[0071] The mono-vinyl aromatic-conjugated diene polymer of the present invention, through a clever structural design, realizes the coexistence of two structures with different benzene amounts and different side group contents in the polymer. Therefore, when it is used as a rubber to prepare vulcanized rubber, it has excellent wear resistance, high wet skid resistance and low rolling resistance, and is a preferred choice for the tread rubber or tread compound of green tires with silica as the main reinforcing agent. The tire has excellent fuel economy, wet grip performance and wear resistance.

[0072] According to the second aspect of the present invention, there is provided a method for preparing a mono-vinyl aromatic-conjugated diene polymer, wherein the method comprises the following steps:

[0073] 1) A step of carrying out a first polymerization reaction on a material A containing a mono-vinyl aromatic monomer, a conjugated diene monomer and a non-polar solvent in the presence of an anionic initiator a;

[0074] 2) In the presence of an anionic initiator b, a step of carrying out a second polymerization reaction on the first polymerization product obtained in step 1) with a material B containing a monovinyl aromatic monomer, a conjugated diene monomer, a polar regulator, and a nonpolar solvent;

[0075] 3) A step of carrying out a coupling reaction on the second polymerization product obtained in step 2) in the presence of a coupling agent.

[0076] According to the present invention, preferably, based on the mass of all polymerization monomers, the mass content of the polymerization monomers in the material A is 10-25%, and the mass content of the polymerization monomers in the material B is 75-90%.

[0077] Specific examples of the mass content of the polymerization monomers in the material A based on the mass of all polymerization monomers, for example, may include: 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., and ranges formed by any two of the above.

[0078] Specific examples of the mass content of the polymerization monomers in the material B based on the mass of all polymerization monomers, for example, may include: 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, etc., and ranges formed by any two of the above.

[0079] According to the present invention, preferably, the material A further contains a polar regulator, and the amount of the polar regulator in the material A is 50 ppm or less; more preferably, the amount of the polar regulator in the material A is 10-40 ppm.

[0080] According to the present invention, preferably, the amount of the polar regulator in the material B is 100-600 ppm; more preferably, the amount of the polar regulator in the material B is 200-400 ppm.

[0081] The polar regulator can be a substance that can regulate the microstructure of the molecular chain and is commonly used in an anionic polymerization system. Specifically, examples of the polar regulator include, but are not limited to: at least one of diethyl ether, dibutyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofurfuryl ethyl ether, dioxane, crown ether, triethylamine, tetramethylethylenediamine, hexamethylphosphoric triamide, potassium tert-butoxide, potassium tert-amylate, potassium laurate, potassium alkylbenzenesulfonate, and sodium alkylbenzenesulfonate, and preferably tetrahydrofurfuryl ethyl ether.

[0082] According to the present invention, the material A is formed by dissolving a monovinyl aromatic monomer, a conjugated diene monomer, and optionally a polar regulator in a nonpolar solvent. In addition, the material B is also formed by dissolving a monovinyl aromatic monomer, a conjugated diene monomer, and a polar regulator in a nonpolar solvent.

[0083] Preferably, the mass percentage content of the monovinyl aromatic monomer in the material A is 25-45%; more preferably, the mass percentage content of the monovinyl aromatic monomer in the material A is 30-40%.

[0084] Preferably, the mass percentage content of the monovinyl aromatic monomer in the material B is 5-25%; more preferably, the mass percentage content of the monovinyl aromatic monomer in the material B is 10-20%.

[0085] Preferably, the mass percentage content of the conjugated diene monomer in the material A is 55-75%; more preferably, the mass percentage content of the conjugated diene monomer in the material A is 60-70%.

[0086] Preferably, the mass percentage content of the conjugated diene monomer in the material B is 75-95%; more preferably, the mass percentage content of the conjugated diene monomer in the material B is 80-90%.

[0087] According to the present invention, the nonpolar solvent is a hydrocarbon solvent and / or an ether solvent. The hydrocarbon solvent can be at least one of cycloalkanes, aromatic hydrocarbons, and straight-chain alkanes having 3 to 10 carbon atoms. Specific examples of the hydrocarbon solvent may include, but are not limited to: at least one of benzene, toluene, xylene, ethylbenzene, propane, butane, n-pentane, cyclopentane, methylcyclopentane, n-heptane, cycloheptane, n-hexane, cyclohexane, n-octane, decane, and cyclooctane. The ether solvent can be a monoether and / or a polyether having 4 to 15 carbon atoms. Specific examples of the ether solvent may include, but are not limited to: tert-butoxyethoxyethane and / or tetrahydrofuran. Among them, these solvents can be used alone or in combination.

[0088] In a preferred embodiment of the present invention, the nonpolar solvent is cyclohexane and n-hexane.

[0089] According to the present invention, the anionic polymerization initiators a and b can be initiators commonly used in the field of anionic polymerization. In a preferred embodiment of the present invention, the anionic initiators a and b are each independently a compound having an RLi structure, where R is a straight-chain or branched-chain alkyl group having 1 to C 10 of the straight-chain or branched-chain alkyl group.

[0090] Preferably, R is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl and n-decyl.

[0091] Specific examples of the anionic initiator may include, but are not limited to: ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-pentyl lithium and n-hexyl lithium. Among them, n-butyl lithium and / or sec-butyl lithium are preferred, and n-butyl lithium is more preferred.

[0092] In a preferred embodiment of the present invention, the anionic polymerization initiators a and b are the same.

[0093] The dosage of the anionic polymerization initiator can be selected according to the expected molecular weight of the mono-vinyl aromatic-conjugated diene polymer. The method for determining the dosage of the initiator according to the expected polymer molecular weight is well known to those skilled in the art and will not be elaborated herein.

[0094] In the present invention, the number average molecular weight and the molecular weight distribution index (Mw / Mn) are measured by gel permeation chromatography using narrow distribution polystyrene as the standard. It should also be noted that in the present invention, the dosage of the anionic polymerization initiator refers to the amount of the anionic polymerization initiator added for initiating the polymerization reaction, and does not include the anionic polymerization initiator added before the polymerization reaction to remove impurities in the polymerization system.

[0095] According to the present invention, preferably, the molar ratio of the anionic initiator a to the anionic initiator b is 1:1.4 - 26, for example, it can be: 1:1.5, 1:1.8, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, 1:22, 1:24, 1:26, etc., and the ranges formed by any two of the above.

[0096] According to the present invention, preferably, the conditions of the first polymerization reaction include: temperature is 50 - 100 °C, time is 0.2 - 1.5 h; preferably, the conditions of the first polymerization reaction include: temperature is 60 - 80 °C, time is 0.5 - 0.8 h.

[0097] According to the present invention, preferably, the conditions of the second polymerization reaction include: temperature is 50 - 100 °C, time is 0.3 - 1.5 h; preferably, the conditions of the second polymerization reaction include: temperature is 60 - 80 °C, time is 0.6 - 1 h.

[0098] In the present invention, the coupling agent is at least one of silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, epoxidized castor oil, divinylbenzene, methoxysilane, dibromosilane and dichlorosilane. Preferably, the coupling agent is at least one of divinylbenzene, silicon tetrachloride and tin tetrachloride. More preferably, the coupling agent is silicon tetrachloride and / or tin tetrachloride. Further preferably, the coupling agent is tin tetrachloride.

[0099] The amount of the coupling agent can be selected according to the expected coupling efficiency. Generally, the amount of the coupling agent is such that in the coupled mono vinyl aromatic-conjugated diene polymer, the content of the coupled polymer is 40-80% by weight, preferably 50-65% by weight; the content of the uncoupled polymer is 20-60% by weight, more preferably 35-50% by weight (i.e., the coupling efficiency is 40-80% by weight, more preferably 50-65% by weight). The polymers before and after coupling can be analyzed by gel permeation chromatography to determine the contents of the coupled polymer and the uncoupled polymer.

[0100] According to the present invention, preferably, the conditions for the coupling reaction include: a temperature of 50-100 °C and a time of 0.3-1 h; more preferably, the conditions for the coupling reaction include: a temperature of 60-80 °C and a time of 0.4-0.8 h.

[0101] According to the present invention, preferably, the method further comprises a step of contacting the second polymerization reaction product obtained in step 3) with a terminator.

[0102] The terminator can be various substances commonly used in the field of anionic polymerization that can terminate the active chain, for example, it can be water and / or alcohol. When the finally prepared mono vinyl aromatic-conjugated diene copolymer is used as a rubber, a tin-containing compound can also be used as the terminator. The tin-containing compound can be trialkyltin chloride, and the alkyl group can be an alkyl group having 1-8 carbon atoms. Specific examples of the tin-containing compound can include, but are not limited to: trimethyltin chloride, triethyltin chloride and tributyltin chloride. The present invention does not particularly limit the amount of the polymerization terminator, as long as the amount of the terminator is sufficient to deactivate the active center. In the actual operation process, the amount of the terminator can be determined according to the amount of the anionic polymerization initiator. Generally, the molar ratio of the terminator to the anionic polymerization initiator can be 0.1-1:1.

[0103] According to the present invention, after terminating the polymerization reaction by adding a polymerization terminator, one or more additives can also be added to the obtained mixture according to specific needs to endow the finally prepared mono vinyl aromatic-conjugated diene copolymer with new properties and / or improve the properties of the finally prepared mono vinyl aromatic-conjugated diene copolymer.

[0104] Specifically, the auxiliary agent may include an antioxidant. The present invention does not particularly limit the type of the antioxidant, and may be various conventional antioxidants in the art. For example, the antioxidant may be a phenolic and / or amine antioxidant. Specifically, the antioxidant may be at least one of 4,6-dioctylthiomethyl o-cresol, tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, tris(2,4-di-tert-butylphenyl)phosphite, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid octadecyl ester, 2,6-di-tert-butyl-p-cresol, tert-butylcatechol and 2,2'-methylene-bis(4-methyl-6-tert-butylphenol). When pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite are mixed for use, the content of tris(2,4-di-tert-butylphenyl) phosphite is preferably not higher than 50 weight %; when octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2,4-di-tert-butylphenyl) phosphite are used in combination, the content of tris(2,4-di-tert-butylphenyl) phosphite is preferably not higher than 50 weight %.

[0105] According to the present invention, the amount of the antioxidant may be a conventional amount in the art. For example, based on 100 parts by weight of the polymer, the amount of the antioxidant may be 0.005-2 parts by weight, preferably 0.1-1 parts by weight.

[0106] According to the present invention, the obtained mixture can be purified and separated by conventional methods to obtain a monovinylarene-conjugated diene polymer. Specifically, the obtained mixture can be centrifuged, filtered, decanted or condensed with hot water to obtain a monovinylarene-conjugated diene copolymer; the obtained mixture can also be stripped to remove the solvent therein to obtain a monovinylarene-conjugated diene polymer.

[0107] The third aspect of the present invention provides the monovinylarene-conjugated diene polymer prepared according to the second aspect of the present invention.

[0108] According to the monovinylarene-conjugated diene polymer of the first aspect and the monovinylarene-conjugated diene polymer of the third aspect of the present invention, two structures with different benzene amounts and different side group contents coexist in the polymer through ingenious structural design. Therefore, when it is used as rubber to prepare vulcanized rubber, it has excellent wear resistance, high anti-wet skid resistance and low rolling resistance. It is a better choice for green tire tread rubber or tread rubber with white carbon black as the main reinforcing agent. The tire has excellent fuel economy, wet grip performance and wear resistance.

[0109] Accordingly, in the fourth aspect of the present invention, there is provided an application of the vinyl aromatic-conjugated diene polymer of the first aspect of the present invention and the vinyl aromatic-conjugated diene polymer of the third aspect of the present invention in a rubber compound for a tire tread.

[0110] In the present invention, the vulcanized rubber obtained by vulcanizing a rubber using the vinyl aromatic-conjugated diene polymer of the first aspect of the present invention and the vinyl aromatic-conjugated diene polymer of the third aspect of the present invention has excellent wear resistance, relatively high wet skid resistance, and relatively low rolling resistance, and is a preferable choice for a green tire tread rubber or a tread compounding rubber using silica as a main reinforcing agent. The tire has excellent fuel economy, wet grip performance, and wear resistance.

[0111] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0112] In the following examples, the microstructure of the polymer was determined using an AVANCE DRX 400 MHz nuclear magnetic resonance spectrometer from Bruker Corporation, Switzerland, with deuterated chloroform as the solvent.

[0113] Test conditions for the 1,2-PB content: Bruker AVANCE400 superconducting nuclear magnetic resonance spectrometer (1H-NMR): the resonance frequency of the 1H nucleus is 300.13 MHz, the spectral width is 2747.253 Hz, the pulse width is 5.0 μs, the number of data points is 16K, the sample tube diameter is 5 mm, the solvent is deuterated chloroform CDCl3, the sample concentration is 15% (W / V), the test temperature is room temperature, the number of scans is 16 times, and the chemical shift of tetramethylsilane is calibrated at 0 ppm.

[0114] Since after the complete reaction of Material B, there will be two polymer chains, R1 and R2, in the polymerization kettle, and it is impossible to separately take out R2 for testing. Therefore, the average mass content of the 1,2-PB structural unit of R1 and R2 is tested, and the 1,2-PB content in R2 is calculated based on the 1,2-PB content in R1 and the average mass content of the 1,2-PB structural unit of R1 and R2.

[0115] The tensile properties were tested according to the method in the national standard "GB / T 1040-92 Test Method for Tensile Properties of Plastics". The tensile testing machine model was AG-20KNG produced by Shimadzu Corporation; the tensile rate was 500 mm / min, and the test temperature was 23 °C. The effective part length of the specimen was 25 mm, and the width was 6 mm. For each group of specimens, 10 parallel experiments were carried out, and the results were averaged.

[0116] Dynamic mechanical properties: The viscoelastic behavior of the samples was tested on an EPLEXOR-500N dynamic thermomechanical analyzer from GABO GmbH, Germany. The sample length was 35 mm, the width was 8 mm, and the thickness was 1.0 mm. The tensile mode was used for the test, with a test frequency of 11 Hz, a temperature range of -100 to 100 °C, a heating rate of 3 °C / min, a static strain of 1%, and a dynamic strain of 0.25%.

[0117] The molecular weight and coupling efficiency were determined using an ALLIANCE 2690 gel permeation chromatograph (GPC) from WATERS Corporation, USA. THF was used as the mobile phase, and narrow-distribution polystyrene was used as the standard sample, with the temperature at 25 °C.

[0118] DIN abrasion: The test was carried out in accordance with the national standard "GB / T 9867-2008 Determination of abrasion resistance of vulcanized rubbers (rotating cylinder abrasion machine method)". The model of the DIN abrasion machine was GT-7012-D, a product of GOODYEAR TEST MACHINE COMPANY, Taiwan, China.

[0119] Preparation of polymer materials A and B

[0120] Material A1: 10.8 g of styrene, 25.2 g of butadiene, and 0.014 g of tetrahydrofurfuryl ethyl ether were added to 1320 g of a cyclohexane / n-hexane (volume ratio 15:85) solvent and mixed evenly for later use.

[0121] Material B1: 64.8 g of styrene, 259.2 g of butadiene, and 0.6 g of tetrahydrofurfuryl ethyl ether were added to 1320 g of a cyclohexane / n-hexane (volume ratio 15:85) solvent and mixed evenly for later use.

[0122] Material A2: 14.4 g of styrene, 21.6 g of butadiene, and 0.027 g of tetrahydrofurfuryl ethyl ether were added to 1320 g of a cyclohexane / n-hexane (volume ratio 15:85) solvent and mixed evenly for later use.

[0123] Material B2: 32.4 g of styrene, 291.6 g of butadiene, and 0.75 g of tetrahydrofurfuryl ethyl ether were added to 1320 g of a cyclohexane / n-hexane (volume ratio 15:85) solvent and mixed evenly for later use.

[0124] Material A3: 31.6 g of styrene, 58.5 g of butadiene, and 0.035 g of tetrahydrofurfuryl ethyl ether were added to 1320 g of a cyclohexane / n-hexane (volume ratio 15:85) solvent and mixed evenly for later use.

[0125] Material B3: 40.5 g of styrene, 229.5 g of butadiene, and 0.9 g of tetrahydrofurfuryl ethyl ether were added to 1320 g of a cyclohexane / n-hexane (volume ratio 15:85) solvent and mixed evenly for later use.

[0126] Material A4: Add 27 g of styrene, 63 g of butadiene, and 0.035 g of tetrahydrofurfuryl ethyl ether to 1320 g of a cyclohexane / n - hexane (volume ratio 15:85) solvent, mix well, and set aside.

[0127] Material B4: Add 54 g of styrene, 216 g of butadiene, and 0.9 g of tetrahydrofurfuryl ethyl ether to 1320 g of a cyclohexane / n - hexane (volume ratio 15:85) solvent, mix well, and set aside.

[0128] Material A5: Add 25.92 g of styrene, 38.88 g of butadiene, and 0.042 g of tetrahydrofurfuryl ethyl ether to 1320 g of a cyclohexane / n - hexane (volume ratio 15:85) solvent, mix well, and set aside.

[0129] Material B5: Add 44.28 g of styrene, 250.92 g of butadiene, and 1.05 g of tetrahydrofurfuryl ethyl ether to 1320 g of a cyclohexane / n - hexane (volume ratio 15:85) solvent, mix well, and set aside.

[0130] Material A6: Add 10.8 g of styrene, 25.2 g of butadiene, and 0.055 g of tetrahydrofurfuryl ethyl ether to 1320 g of a cyclohexane / n - hexane (volume ratio 15:85) solvent, mix well, and set aside.

[0131] Material B6: Add 64.8 g of styrene, 259.2 g of butadiene, and 1.2 g of tetrahydrofurfuryl ethyl ether to 1320 g of a cyclohexane / n - hexane (volume ratio 15:85) solvent, mix well, and set aside.

[0132] Example 1

[0133] In a 5 L stainless - steel polymerization kettle, add Material A1, start stirring. When the temperature in the polymerization kettle reaches 60 °C, add 0.24 mmol of n - butyllithium to the polymerization kettle. After reacting for 0.5 h (the first polymerization reaction generates the first styrene - butadiene polymerization chain R1, the same below), take a sample to test the molecular weight and microstructure. Then add 6.24 mmol of n - butyllithium to the polymerization kettle, and then add Material B1, and continue the polymerization reaction for 0.8 h (the second polymerization reaction generates the second styrene - butadiene polymerization chain R2 and the first styrene - butadiene polymerization chain R1 - the second styrene - butadiene polymerization chain R2, the same below). After the monomers have completely reacted, add 0.0318 g of silicon tetrachloride for a coupling reaction for 0.4 h. Finally, add isopropanol to terminate the reaction, and add antioxidant 1076. The rubber solution is treated by wet coagulation. Specifically, the rubber solution is boiled in high - pressure steam at about 140 °C for 12 minutes, and after removing about 95% of the solvent, set the temperature of the open - mill to 100 °C to remove the remaining moisture and solvent in the rubber material, and obtain a dry rubber with a volatile content of less than 0.5%, and set aside.

[0134] The number-average molecular weight of R1 in the polymer obtained in this example was measured to be 148,961 g / mol. Based on the mass of the butadiene structural unit in R1, the content of the 1,2-PB structural unit was 15.3%; the number-average molecular weight of R2 was 50,369 g / mol. Based on the mass of the butadiene structural unit in R2, the content of the 1,2-PB structural unit was 52.6%; the coupling efficiency was 61.2%.

[0135] Example 2

[0136] In a 5 L stainless steel polymerization kettle, material A2 was added, and stirring was started. When the temperature in the polymerization kettle reached 65 °C, 0.3 mmol of n-butyllithium was added to the polymerization kettle. After reacting for 0.6 h, a sample was taken to test the molecular weight and microstructure. Then 3.75 mmol of n-butyllithium was added to the polymerization kettle, and then material B2 was added. The polymerization reaction was continued for 0.9 h. After the monomers reacted completely, 0.191 g of silicon tetrachloride was added for a coupling reaction for 0.5 h. Finally, isopropanol was added to terminate the reaction, and antioxidant 1076 was added. The rubber solution was treated by wet coagulation. Specifically, the rubber solution was boiled in high-pressure steam at about 140 °C for 12 minutes. After removing about 95% of the solvent, the temperature of the open mill was set to 100 °C to remove the residual moisture and solvent in the rubber material, and a dry rubber with a volatile content of less than 0.5% was obtained for standby.

[0137] The number-average molecular weight of R1 in the polymer obtained in this example was measured to be 120,154 g / mol. Based on the mass of the butadiene structural unit in R1, the content of the 1,2-PB structural unit was 18.6%; the number-average molecular weight of R2 was 79,869 g / mol. Based on the mass of the butadiene structural unit in R2, the content of the 1,2-PB structural unit was 55.9%; the coupling efficiency was 63.2%.

[0138] Example 3

[0139] In a 5 L stainless steel polymerization kettle, material A3 was added, and stirring was started. When the temperature in the polymerization kettle reached 70 °C, 1.125 mmol of n-butyllithium was added to the polymerization kettle. After reacting for 0.7 h, a sample was taken to test the molecular weight and microstructure. Then 1.575 mmol of n-butyllithium was added to the polymerization kettle, and then material B3 was added. The polymerization reaction was continued for 1 h. After the monomers reacted completely, 0.08 g of silicon tetrachloride was added for a coupling reaction for 0.8 h. Finally, isopropanol was added to terminate the reaction, and antioxidant 1076 was added. The rubber solution was treated by wet coagulation. Specifically, the rubber solution was boiled in high-pressure steam at about 140 °C for 12 minutes. After removing about 95% of the solvent, the temperature of the open mill was set to 100 °C to remove the residual moisture and solvent in the rubber material, and a dry rubber with a volatile content of less than 0.5% was obtained for standby.

[0140] The number-average molecular weight of R1 in the polymer obtained in this example was measured to be 81002 g / mol. Based on the mass of the butadiene structural unit in R1, the content of the 1,2-PB structural unit was 20.8%; the number-average molecular weight of R2 was 99856 g / mol. Based on the mass of the butadiene structural unit in R2, the content of the 1,2-PB structural unit was 51.7%; the coupling efficiency was 58.2%.

[0141] Example 4

[0142] In a 5L stainless-steel polymerization kettle, add Material A4, start stirring. When the temperature in the polymerization kettle reaches 60 °C, add 0.6 mmol of n-butyllithium to the polymerization kettle. After reacting for 0.8 h, take a sample to test the molecular weight and microstructure. Then add 2.1 mmol of n-butyllithium to the polymerization kettle, and then add Material B4. Continue the polymerization reaction for 0.8 h. After the monomers have completely reacted, add 0.107 g of silicon tetrachloride for coupling reaction for 0.6 h. Finally, add isopropanol to terminate the reaction, and add antioxidant 1076. The rubber solution is treated by wet coagulation. Specifically, the rubber solution is boiled in high-pressure steam at about 140 °C for 12 minutes. After removing about 95% of the solvent, set the temperature of the open mill to 100 °C to remove the residual moisture and solvent in the rubber material, and obtain dry rubber with a volatile content of less than 0.5% for standby.

[0143] The number-average molecular weight of R1 in the polymer obtained in this example was measured to be 148956 g / mol. Based on the mass of the butadiene structural unit in R1, the content of the 1,2-PB structural unit was 20.2%; the number-average molecular weight of R2 was 99256 g / mol. Based on the mass of the butadiene structural unit in R2, the content of the 1,2-PB structure was 50.9%; the coupling efficiency was 52.2%.

[0144] Example 5

[0145] In a 5L stainless-steel polymerization kettle, add Material A5, start stirring. When the temperature in the polymerization kettle reaches 70 °C, add 0.648 mmol of n-butyllithium to the polymerization kettle. After reacting for 0.7 h, take a sample to test the molecular weight and microstructure. Then add 2.304 mmol of n-butyllithium to the polymerization kettle, and then add Material B5. Continue the polymerization reaction for 1 h. After the monomers have completely reacted, add 0.117 g of silicon tetrachloride for coupling reaction for 0.8 h. Finally, add isopropanol to terminate the reaction, and add antioxidant 1076. The rubber solution is treated by wet coagulation. Specifically, the rubber solution is boiled in high-pressure steam at about 140 °C for 12 minutes. After removing about 95% of the solvent, set the temperature of the open mill to 100 °C to remove the residual moisture and solvent in the rubber material, and obtain dry rubber with a volatile content of less than 0.5% for standby.

[0146] The number-average molecular weight of R1 in the polymer obtained in this example was measured to be 99,886 g / mol. Based on the mass of the butadiene structural unit in R1, the content of the 1,2-PB structural unit was 25.2%; the number-average molecular weight of R2 was 98,879 g / mol. Based on the mass of the butadiene structural unit in R2, the content of the 1,2-PB structure was 55.6%; the coupling efficiency was 60.2%.

[0147] Example 6

[0148] In a 5 L stainless steel polymerization kettle, material A6 was added, and stirring was started. When the temperature in the polymerization kettle reached 75 °C, 0.81 mmol of n-butyllithium was added to the polymerization kettle. After reacting for 0.6 h, a sample was taken to test the molecular weight and microstructure. Then 5.094 mmol of n-butyllithium was added to the polymerization kettle, and then material B6 was added. The polymerization reaction was continued for 0.9 h. After the monomers reacted completely, 0.26 g of silicon tetrachloride was added for a coupling reaction for 0.8 h. Finally, isopropanol was added to terminate the reaction, and antioxidant 1076 was added. The rubber solution was treated by wet coagulation. Specifically, the rubber solution was boiled in high-pressure steam at about 140 °C for 12 minutes. After removing about 95% of the solvent, the temperature of the open mill was set to 100 °C to remove the remaining moisture and solvent in the rubber material, and a dry rubber with a volatile content of less than 0.5% was obtained for standby.

[0149] The number-average molecular weight of R1 in the polymer obtained in this example was measured to be 79,899 g / mol. Based on the mass of the butadiene structural unit in R1, the content of the 1,2-PB structural unit was 28.4%; the number-average molecular weight of R2 was 50,068 g / mol. Based on the mass of the butadiene structural unit in R2, the content of the 1,2-PB structure was 58.4%; the coupling efficiency was 61.5%.

[0150] Comparative Example 1

[0151] In a 5 L stainless steel polymerization kettle, 2640 g of cyclohexane / n-hexane (volume ratio 15:85) solvent, 72 g of styrene, 288 g of butadiene, and 1.05 g of tetrahydrofurfuryl ethyl ether were added, and stirring was started. When the temperature in the polymerization kettle reached 65 °C, 2.4 mmol of n-butyllithium was added to the polymerization kettle. After reacting for 0.9 h, 1.2 g of silicon tetrachloride was added for a coupling reaction for 0.4 h. Finally, isopropanol was added to terminate the reaction, and antioxidant 1076 was added. The rubber solution was treated by wet coagulation.

[0152] The number-average molecular weight of the polymer obtained in this comparative example before coupling was measured to be 148,675 g / mol, the coupling efficiency was 56.9%, and the 1,2-PB content was 52.6%.

[0153] Comparative Example 2

[0154] In a 5L stainless steel polymerization kettle, add material A2, start stirring. When the temperature in the polymerization kettle reaches 65 °C, add 0.3 mmol of n-butyllithium to the polymerization kettle. After reacting for 0.6 h, take a sample to test the molecular weight and microstructure. Then add 3.75 mmol of n-butyllithium to the polymerization kettle, and then add material B2 (tetrahydrofurfuryl ethyl ether is not added to B2), and continue the polymerization reaction for 0.9 h. After the monomers react completely, add 0.191 g of silicon tetrachloride for coupling reaction for 0.5 h. Finally, add isopropanol to terminate the reaction, and add antioxidant 1076. The rubber solution is treated by wet coagulation. Specifically, the rubber solution is boiled in high-pressure steam at about 140 °C for 12 minutes. After removing about 95% of the solvent, set the temperature of the open mill to 100 °C to remove the residual moisture and solvent in the rubber material, and obtain dry rubber with a volatile content of less than 0.5%, for standby.

[0155] It is measured that the number-average molecular weight of R1 in the polymer obtained in this example is 121038 g / mol. Based on the mass of the butadiene structural unit in R1, the content of the 1,2-PB structural unit is 18.6%; the number-average molecular weight of R2 is 80543 g / mol. Based on the mass of the butadiene structural unit in R2, the content of the 1,2-PB structural unit is 18.5%; the coupling efficiency is 62.9%.

[0156] Test Example

[0157] Reinforce the polymers (100 parts by weight) prepared in the above examples and comparative examples respectively using a silica system. The silica is selected as 165GR from Rhodia, and the addition amount of silica is 60 parts by weight, 10 parts by weight of 8# reference carbon black, 15 parts by weight of processing oil TDAE, 3.0 parts by weight of zinc oxide, 2.0 parts by weight of stearic acid, 1.5 parts by weight of sulfur, 2.0 parts by weight of antioxidant 4020, 1.5 parts by weight of accelerator D, and 1.5 parts by weight of accelerator TBBS. And in the tests of each example and comparative example, only the source of the polymer is different, and the rest are the same. The internal mixer is of the American Farrell BR1600 type, and the cavity volume is 1.5 L; the flat vulcanizer is produced by Pan Shi Oil Pressure Industry (Anhui) Co., Ltd., and the model is P-50-PCD-3L (vulcanization temperature is 150 °C, vulcanization pressure is 20 MPa, and vulcanization time is 50 min). Obtain vulcanized rubber.

[0158] The properties of the obtained vulcanized rubber are shown in Table 1.

[0159] Table 1

[0160]

[0161] As can be seen from the above results, the vinyl aromatic-conjugated diene polymer with a diversified structure provided by the present invention realizes the coexistence of two structures with different benzene amounts and different side group contents in the polymer through a clever structural design. Therefore, the polymer composition provided by the present invention has excellent wear resistance, high wet skid resistance and low rolling resistance, and is a preferred choice for green tire tread rubber or tread compound with silica as the main reinforcing agent. The tire has excellent fuel economy, wet grip performance and wear resistance at the same time.

[0162] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of technical features. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A vinyl aromatic-conjugated diene polymer, characterized in that, The polymer contains a first vinyl aromatic-conjugated diene polymerization chain, a second vinyl aromatic-conjugated diene polymerization chain, and a structure formed by coupling the first vinyl aromatic-conjugated diene polymerization chain and the second vinyl aromatic-conjugated diene polymerization chain. Among them, the number-average molecular weight of the first vinyl aromatic-conjugated diene polymerization chain is 70,000-180,000 g / mol, the number-average molecular weight of the second vinyl aromatic-conjugated diene polymerization chain is 40,000-120,000 g / mol. Based on the mass of the conjugated diene structural unit in the first vinyl aromatic-conjugated diene polymerization chain, the content of the conjugated diene side group structure in the first vinyl aromatic-conjugated diene polymerization chain is 10-30%, and based on the mass of the conjugated diene structural unit in the second vinyl aromatic-conjugated diene polymerization chain, the content of the conjugated diene side group in the second vinyl aromatic-conjugated diene polymerization chain is 50-65%.

2. The vinyl aromatic-conjugated diene polymer according to claim 1, wherein, The coupling efficiency is 40-80% by weight, preferably 50-65% by weight; and / or The coupling structural unit is derived from at least one of silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, epoxidized castor oil, divinylbenzene, methoxysilane, dibromosilane, and dichlorosilane, preferably from silicon tetrachloride.

3. The vinyl aromatic-conjugated diene polymer according to claim 1, wherein, Based on the mass of the vinyl aromatic-conjugated diene polymer, the mass content of the first vinyl aromatic-conjugated diene polymerization chain is 10-25%, and the mass content of the second vinyl aromatic-conjugated diene polymerization chain is 75-90%; and / or Based on the mass of the first vinyl aromatic-conjugated diene polymerization chain, the mass content of the vinyl aromatic structural unit in the first vinyl aromatic-conjugated diene polymerization chain is 25-45%, preferably 30-40%; and / or Based on the mass of the second vinyl aromatic-conjugated diene polymerization chain, the mass content of the vinyl aromatic in the second vinyl aromatic-conjugated diene polymerization chain is 5-25%, preferably 10-20%.

4. The vinyl aromatic-conjugated diene polymer according to any one of claims 1-3, wherein, The conjugated diene is selected from at least one of butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, and 2,3-dimethylbutadiene; or The conjugated diene is butadiene.

5. The vinyl aromatic-conjugated diene polymer according to any one of claims 1-3, wherein, The vinyl aromatic is selected from at least one of styrene, vinyltoluene, α-methylstyrene, 4-tert-butylstyrene, 4-methylstyrene, 3,5-diethylstyrene, 3,5-din-butylstyrene, 4-n-propylstyrene, and 4-dodecylstyrene; or The vinyl aromatic is styrene.

6. A method for preparing a mono vinyl aromatic-conjugated diene polymer, characterized in that, This method includes the following steps: 1) The step of carrying out a first polymerization reaction on a material A containing a vinyl aromatic monomer, a conjugated diene monomer, and a non-polar solvent in the presence of an anionic initiator a; 2) The step of carrying out a second polymerization reaction on the first polymerization reaction product obtained in step 1 with a material B containing a vinyl aromatic monomer, a conjugated diene monomer, a polar regulator, and a non-polar solvent in the presence of an anionic initiator b; 3) The step of carrying out a coupling reaction on the second polymerization product obtained in step 2 in the presence of a coupling agent.

7. The method according to claim 6, wherein The molar ratio of the anionic initiator a to the anionic initiator b is 1:1.4 - 26.

8. The method according to claim 6, wherein Based on the total mass of the polymerization monomers, the mass content of the polymerization monomers in the material A is 10 - 25%, and the mass content of the polymerization monomers in the material B is 75 - 90%.

9. The method according to any one of claims 6 - 8, wherein, The material A further contains a polar regulator, and the dosage of the polar regulator in the material A is 50 ppm or less, preferably 10 - 40 ppm; and / or The dosage of the polar regulator in the material B is 100 - 600 ppm, preferably 200 - 400 ppm.

10. The method according to any one of claims 6-8, wherein, The mass percentage content of the mono-vinyl aromatic hydrocarbon monomer in the material A is 25 - 45%, preferably 30 - 40%; Preferably, the mass percentage content of the mono-vinyl aromatic hydrocarbon monomer in the material B is 5 - 25%, preferably 10 - 20%.

11. The method according to any one of claims 6-8, wherein, The conjugated diene is selected from at least one of butadiene, isoprene, 1,3 - pentadiene, 1,3 - hexadiene, and 2,3 - dimethylbutadiene; or The conjugated diene is butadiene.

12. The method according to any one of claims 6-8, wherein, The mono-vinyl aromatic hydrocarbon is selected from at least one of styrene, vinyltoluene, α - methylstyrene, 4 - tert - butylstyrene, 4 - methylstyrene, 3,5 - diethylstyrene, 3,5 - di - n - butylstyrene, 4 - n - propylstyrene, and 4 - dodecylstyrene; or The mono-vinyl aromatic hydrocarbon is styrene.

13. The method according to any one of claims 6 - 8, wherein, The anionic initiator a and the anionic initiator b are each independently a compound having an RLi structure, where R is a straight-chain or branched-chain alkyl group having 1 to C 10 ; or R is selected from methyl, ethyl, n - propyl, isopropyl, n - butyl, sec - butyl, isobutyl, tert - butyl, n - pentyl, isopentyl, tert - pentyl, neopentyl, n - hexyl, n - heptyl, n - octyl, and n - decyl.

14. The method according to any one of claims 6-8, wherein, The polar regulator is selected from at least one of diethyl ether, dibutyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofurfuryl ether, dioxane, crown ether, triethylamine, tetramethylethylenediamine, hexamethylphosphoric triamide, potassium tert - butoxide, potassium tert - pentoxide, potassium laurate, potassium alkylbenzenesulfonate, and sodium alkylbenzenesulfonate, preferably tetrahydrofurfuryl ether.

15. The method according to any one of claims 6 - 8, wherein, The coupling agent is selected from at least one of silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, epoxidized castor oil, divinylbenzene, methoxysilane, dibromosilane, and dichlorosilane, preferably silicon tetrachloride.

16. A mono-vinyl aromatic hydrocarbon - conjugated diene polymer prepared by the method according to any one of claims 6 - 15.

17. Use of the mono-vinyl aromatic hydrocarbon - conjugated diene polymer according to any one of claims 1 - 5 and 16 in a rubber compound for a tire tread.

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