A bimodal polybutadiene and its molecular weight and microstructure controllable polymerization method and application

Abstract

A bimodal polybutadiene and a molecular weight and microstructure controllable polymerization method and application thereof. The present invention belongs to the field of conjugated diene catalytic polymerization. The purpose of the present invention is to solve the technical problem that the molecular weight distribution of polybutadiene obtained by the existing method is single, which leads to a relatively single performance and cannot take into account excellent mechanical properties and processing performance. The method of the present invention: under anhydrous and oxygen-free conditions, an iron-based catalyst, an alkyl aluminum, butadiene, and a solvent are added to a reactor in any order, and the bimodal polybutadiene is obtained by constant temperature polymerization at 20 to 30°C. The content of trans-1,4 structure in the obtained polymer product is 45-83%, the number average molecular weight range of the low molecular weight part is 0.5-22 million g / mol, the molecular weight distribution is 1.0-2.2, and the number average molecular weight range of the high molecular weight part is 80-4.6 million, and the molecular weight distribution is 1.0-2.0.

Description

Technical Field

[0001] The invention belongs to the field of conjugated diene catalytic polymerization, and specifically relates to a bimodal polybutadiene and a molecular weight and microstructure controllable polymerization method and application thereof. Background Art

[0002] One of the important basic industries of the national economy is the rubber industry, and rubber products have been widely used in transportation, aviation, machinery, and national defense. Tires can be made of rubbers of different components. Among them, high trans-1,4-polybutadiene (HTPB) has the ability to crystallize at room temperature when the trans-1,4 content is greater than 90%. When the trans-1,4 content is between 40% and 80%, polybutadiene behaves as an elastomer, with low rolling resistance, high anti-slip properties, high wear resistance, high tensile strength, high hardness, excellent fatigue resistance and many other highly characteristic characteristics, which have attracted widespread attention. It is generally used in the tire industry to make rubber to enhance the performance of tires. It is one of the ideal rubber materials for the development of high-tech and environmentally friendly tires.

[0003] Butadiene monomer can be used to prepare high trans-1,4-polyconjugated diene rubber through catalytic polymerization. Currently, the catalytic systems that can complete the preparation of high trans-1,4-polyconjugated diene rubber mainly include: chromium, rare earth, vanadium and iron. In recent years, in order to implement the national green environmental protection concept, scientists have turned their attention to environmentally friendly iron catalysts. However, the molecular weight distribution of polybutadiene obtained by the existing methods is single, which leads to relatively single performance and cannot take into account excellent mechanical properties and processing properties. Therefore, how to obtain polybutadiene with excellent comprehensive performance is an urgent problem to be solved.

[0004] There are still few studies on the controlled polymerization of butadiene with bimodal molecular weight distribution using iron-based catalysts. The high molecular weight part of the polymer can provide certain mechanical properties, and the low molecular weight part can improve its processing properties. Therefore, it is very important to study the use of iron-based catalysts to catalyze butadiene to obtain polybutadiene with bimodal molecular weight distribution. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problem that the polybutadiene obtained by the existing method has a single molecular weight distribution, which leads to relatively single performance and cannot take into account both excellent mechanical properties and processing properties, and to provide a bimodal polybutadiene and a molecular weight and microstructure controllable polymerization method and application thereof.

[0006] One of the objects of the present invention is to provide a method for controlling the molecular weight and microstructure of bimodal polybutadiene polymerization, which is carried out according to the following steps:

[0007] Under anhydrous and oxygen-free conditions, an iron-based catalyst, alkyl aluminum, butadiene and a solvent are added to a reactor in any order, and the polymerization is carried out at a constant temperature of -20 to 30°C for 10 to 360 minutes. After the reaction is completed, a quencher and an anti-aging agent are added, and the reaction is washed, separated and purified to obtain bimodal polybutadiene.

[0008] It is further defined that the iron-based catalyst is any one of the following structures:

[0009]

[0010] In a further embodiment, the alkylaluminum is methylaluminoxane, modified methylaluminoxane or methylaluminoxane from which the solvent has been drained.

[0011] It is further defined that the solvent is one or a mixture of two of hexane, n-heptane, cyclohexane, pentane, petroleum ether and toluene in any ratio.

[0012] It is further defined that the molar ratio of butadiene to the iron element in the iron-based catalyst is (100-3000):1.

[0013] It is further defined that the molar ratio of the aluminum element in the alkyl aluminum to the iron element in the iron-based catalyst is (300-1000):1.

[0014] It is further defined that the volume ratio of the solvent to butadiene is (2.5-50):1.

[0015] A second object of the present invention is to provide a bimodal molecular weight distribution polybutadiene prepared by the above method.

[0016] It is further defined that the trans-1,4 structure content in the bimodal molecular weight distribution polybutadiene is 45-83%, the number average molecular weight range of the low molecular weight part is 0.5-220,000 g / mol, the molecular weight distribution is 1.0-2.2, and the number average molecular weight range of the high molecular weight part is 800,000-4.6 million, and the molecular weight distribution is 1.0-2.0.

[0017] The third object of the present invention is to provide an application of the bimodal molecular weight distribution polybutadiene prepared by the above method in the preparation of high-performance tires.

[0018] Compared with the prior art, the present invention has the following significant effects:

[0019] The present invention uses cheap iron as the metal center and pyridine imine / amine as the main ligand skeleton to provide a new and efficient iron catalyst system with controllable bimodal molecular weight distribution of polybutadiene. The specific advantages are as follows:

[0020] 1) The number average molecular weight of the polybutadiene obtained by the present invention is 0.5-220,000 g / mol, with a molecular weight distribution of 1.0-2.2; the high molecular weight is 800,000-4.6 million, with a molecular weight distribution of 1.0-2.0. The trans-1,4 structure content of the polybutadiene rubber is 45-83%, and the proportion of the (1,2-) structure is 15%-48%.

[0021] 2) The iron catalytic system described in the present invention is a pyridine imine / amine iron complex with a clear molecular structure, which has the advantages of simple preparation, high activity and low cost.

[0022] 3) The bimodal molecular weight distribution and microstructure proportion of the polymer show regular changes with the polymerization temperature and the iron-aluminum ratio. The proportion of the trans-1,4 structure content increases with the increase of temperature. When the polymerization temperature exceeds 30°C, polybutadiene with a bimodal molecular weight distribution cannot be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The polybutadiene obtained in Example 2 1 HNMR spectra;

[0024] Figure 2 The polybutadiene obtained in Example 4 1 HNMR spectra;

[0025] Figure 3 The polybutadiene obtained in Comparative Example 2 1 HNMR spectra;

[0026] Figure 4 The polybutadiene obtained in Comparative Example 3 1 HNMR spectrum. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0029] The terms "comprising," "including," "having," "containing," or any other variations thereof, as used in the following examples, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus comprising the listed elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0030] When equivalent, concentration or other value or parameter is represented by the range limited by range, preferred range or a series of upper preferred value and lower preferred value, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the scope is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the scope is intended to include its end value and all integers and fractions within the scope. In the present application specification and claims, range limitation can be combined and / or interchanged, if these ranges are not otherwise stated, include all sub-ranges contained therein.

[0031] The indefinite articles "a" and "an" before the elements or components of the present invention have no limitation on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0032] Example 1

[0033] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), methylaluminoxane (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence, and the polymerization was carried out at a constant temperature of -20°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0034] The obtained product polybutadiene: high number average molecular weight (Mn): 2.69 million g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 52%; low number average molecular weight (Mn): 150,000 g / mol, molecular weight distribution (PDI): 1.2, peak area accounts for 48%. The proportion of different structures: trans-1,4-structure accounts for 50%, 1,2-structure accounts for 50%.

[0035] Example 2

[0036] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), methylaluminoxane (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 0°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0037] The obtained product polybutadiene: high number average molecular weight (Mn): 2.11 million g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 60%; low number average molecular weight (Mn): 140,000 g / mol, molecular weight distribution (PDI): 1.1, peak area accounts for 40%. The proportion of different structures: trans-1,4-structure accounts for 52%, 1,2-structure accounts for 48%.

[0038] Example 3

[0039] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), methylaluminoxane (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 20°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified. The yield was >99%.

[0040] The obtained product polybutadiene: high number average molecular weight (Mn): 2.92 million g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 42%; low number average molecular weight (Mn): 170,000 g / mol, molecular weight distribution (PDI): 1.2, peak area accounts for 58%. The proportion of different structures: trans-1,4-structure accounts for 57%, 1,2-structure accounts for 39%.

[0041] Example 4

[0042] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), methylaluminoxane (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reactor was washed three times with ethanol, and polybutadiene was separated and purified. The yield was >99%.

[0043] The obtained product polybutadiene: high number average molecular weight (Mn): 1.73 million g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 18%; low number average molecular weight (Mn): 130,000 g / mol, molecular weight distribution (PDI): 1.5, peak area accounts for 82%. The proportion of different structures: trans-1,4-structure accounts for 70%, 1,2-structure accounts for 26%.

[0044] Example 5

[0045] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), methylaluminoxane (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 30°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified. The yield was >99%.

[0046] The obtained product polybutadiene: high number average molecular weight (Mn): 4.57 million g / mol, molecular weight distribution (PDI): 1.2, peak area accounting for 7%; low number average molecular weight (Mn): 180,000 g / mol, molecular weight distribution (PDI): 1.6, peak area accounting for 93%. The proportion of different structures: trans-1,4-structure accounts for 76%, 1,2-structure accounts for 24%.

[0047] Example 6

[0048] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), butadiene (2000 equiv.), and methylaluminoxane (500 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0049] The obtained product polybutadiene: low number average molecular weight (Mn): 150,000 g / mol, molecular weight distribution (PDI): 1.6, peak area accounting for 53%, high molecular weight (Mn): 1.51 million g / mol, molecular weight distribution (PDI): 1.5, peak area accounting for 47%. The proportion of different structures: trans-1,4-structure accounts for 47%, 1,2-structure accounts for 37%.

[0050] Example 7

[0051] The dry and clean reactor was evacuated and replaced with nitrogen several times, and methylaluminoxane (500 equiv.), toluene (5 mL), butadiene (2000 equiv.), and iron-based catalyst Fe1 (10 μmol, 1 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an antioxidant was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0052] The obtained product polybutadiene: low number average molecular weight (Mn): 80,000 g / mol, molecular weight distribution (PDI): 2.1, peak area accounts for 73%, high molecular weight (Mn): 2.26 million g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 27%. The proportion of different structures: trans-1,4-structure accounts for 53%, 1,2-structure accounts for 37%.

[0053] Example 8

[0054] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), DMAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0055] The obtained product polybutadiene: low number average molecular weight (Mn): 190,000 g / mol, molecular weight distribution (PDI): 2.0, peak area accounts for 85%, high molecular weight (Mn): 3.62 million g / mol, molecular weight distribution (PDI): 1.3, peak area accounts for 15%. The proportion of different structures: trans-1,4-structure accounts for 68%, 1,2-structure accounts for 22%.

[0056] Example 9

[0057] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), MMAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 80%.

[0058] The obtained product polybutadiene: low number average molecular weight (Mn): 80,000 g / mol, molecular weight distribution (PDI): 2.2, peak area accounting for 88%, high molecular weight (Mn): 3.52 million g / mol, molecular weight distribution (PDI): 1.4, peak area accounting for 12%. The proportion of different structures: trans-1,4-structure accounts for 66%, 1,2-structure accounts for 28%.

[0059] Example 10

[0060] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), n-hexane (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 98%.

[0061] The obtained product polybutadiene: low number average molecular weight (Mn): 130,000 g / mol, molecular weight distribution (PDI): 1.7, peak area accounts for 83%, high molecular weight (Mn): 2.6 million g / mol, molecular weight distribution (PDI): 1.4, peak area accounts for 17%. The proportion of different structures: trans-1,4-structure accounts for 70%, 1,2-structure accounts for 24%

[0062] Embodiment 11

[0063] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), cyclohexane (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence, and the polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0064] The obtained product polybutadiene: low number average molecular weight (Mn): 150,000 g / mol, molecular weight distribution (PDI): 1.5, peak area accounts for 80%, high molecular weight (Mn): 2.76 million g / mol, molecular weight distribution (PDI): 1.7, peak area accounts for 20%. The proportion of different structures: trans-1,4-structure accounts for 74%, 1,2-structure accounts for 26%

[0065] Example 12

[0066] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 60 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 90%.

[0067] The obtained product polybutadiene: low number average molecular weight (Mn): 70,000 g / mol, molecular weight distribution (PDI): 1.3, peak area accounts for 79%, high molecular weight (Mn): 2.2 million g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 21%. The proportion of different structures: trans-1,4-structure accounts for 69%, 1,2-structure accounts for 24%

[0068] Embodiment 13

[0069] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 90 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 98%.

[0070] The obtained product polybutadiene: low number average molecular weight (Mn): 90,000 g / mol, molecular weight distribution (PDI): 1.4, peak area accounting for 81%, high molecular weight (Mn): 2.56 million g / mol, molecular weight distribution (PDI): 1.5, peak area accounting for 19%. The proportion of different structures: trans-1,4-structure accounts for 61%, 1,2-structure accounts for 26%.

[0071] Embodiment 14

[0072] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe4 (10 μmol, 1 equiv.), toluene (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0073] The obtained product polybutadiene: low number average molecular weight (Mn): 40,000 g / mol, molecular weight distribution (PDI): 1.6, peak area accounting for 73%, high molecular weight (Mn): 890,000 g / mol, molecular weight distribution (PDI): 1.7, peak area accounting for 27%. The proportion of different structures: trans-1,4-structure accounts for 69%, 1,2-structure accounts for 31%.

[0074] Embodiment 15

[0075] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe7 (10 μmol, 1 equiv.), toluene (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0076] The obtained product polybutadiene: low number average molecular weight (Mn): 50,000 g / mol, molecular weight distribution (PDI): 1.5, peak area accounts for 80%, high molecular weight (Mn): 1.07 million g / mol, molecular weight distribution (PDI): 1.5, peak area accounts for 20%. The proportion of different structures: trans-1,4-structure accounts for 67%, 1,2-structure accounts for 31%.

[0077] Example 16

[0078] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe9 (10 μmol, 1 equiv.), toluene (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0079] The obtained product polybutadiene: low number average molecular weight (Mn): 70,000 g / mol, molecular weight distribution (PDI): 1.4, peak area accounting for 83%, high molecular weight (Mn): 1.97 million g / mol, molecular weight distribution (PDI): 1.3, peak area accounting for 17%. The proportion of different structures: trans-1,4-structure accounts for 66%, 1,2-structure accounts for 34%.

[0080] Embodiment 17

[0081] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), MAO (1000 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 90%.

[0082] The obtained product polybutadiene: low number average molecular weight (Mn): 130,000 g / mol, molecular weight distribution (PDI): 1.8, peak area accounts for 80%, high molecular weight (Mn): 3.52 million g / mol, molecular weight distribution (PDI): 1.4, peak area accounts for 20%. The proportion of different structures: trans-1,4-structure accounts for 64%, 1,2-structure accounts for 29%.

[0083] Embodiment 18

[0084] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), MAO (300 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 99%.

[0085] The obtained product polybutadiene: low number average molecular weight (Mn): 220,000 g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 91%, high molecular weight (Mn): 4.53 million g / mol, molecular weight distribution (PDI): 1.2, peak area accounts for 9%. The proportion of different structures: trans-1,4-structure accounts for 70%, 1,2-structure accounts for 25%.

[0086] Comparative Example 1

[0087] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 40°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reactor was washed three times with ethanol, and polybutadiene was separated and purified. The yield was >99%.

[0088] The obtained product polybutadiene has low number average molecular weight (Mn): 110,000 g / mol, molecular weight distribution (PDI): 1.8, peak area accounts for 100%. The proportion of different structures: trans-1,4-structure accounts for 79%, and 1,2-structure accounts for 18%.

[0089] Comparative Example 2

[0090] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), MAO (500 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 50°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reactor was washed three times with ethanol, and polybutadiene was separated and purified. The yield was >99%.

[0091] The obtained product polybutadiene has low number average molecular weight (Mn): 80,000 g / mol, molecular weight distribution (PDI): 1.8, peak area accounts for 100%. The proportion of different structures: trans-1,4-structure accounts for 83%, and 1,2-structure accounts for 17%.

[0092] Comparative Example 3

[0093] The dry and clean reactor was evacuated and replaced with nitrogen several times, and iron-based catalyst Fe1 (10 μmol, 1 equiv.), toluene (5 mL), methylaluminoxane (100 equiv.), and butadiene (2000 equiv.) were added into the reactor in sequence. The polymerization was carried out at a constant temperature of 25°C for 120 min. After the reaction, 1 mL of an anti-aging agent was added, and 10 mL of a methanol-hydrochloric acid solution (MeOH / HCl=50 / 1) was added to quench the reaction. The reaction was washed three times with ethanol, and polybutadiene was separated and purified to obtain a yield of 97%.

[0094] The obtained product polybutadiene has low number average molecular weight (Mn): 230,000 g / mol, molecular weight distribution (PDI): 1.6, peak area accounts for 100%. The proportion of different structures: trans-1,4-structure accounts for 74%, and 1,2-structure accounts for 21%.

[0095] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for controlling the molecular weight and microstructure of bimodal polybutadiene, characterized in that: Follow these steps: Under anhydrous and oxygen-free conditions, an iron-based catalyst, alkyl aluminum, butadiene, and a solvent are added to a reactor in any order, and polymerized at a constant temperature of -20 to 30°C for 10 to 360 minutes. After the reaction, a quencher and an anti-aging agent are added, and the mixture is washed, separated, and purified to obtain bimodal polybutadiene. The iron-based catalyst is any one of the following structures: ； The molar ratio of the aluminum element in the alkyl aluminum to the iron element in the iron-based catalyst is (300-1000):

1.

2. The method according to claim 1, characterized in that The alkylaluminum is methylaluminoxane, modified methylaluminoxane or methylaluminoxane from which the solvent has been drained.

3. The method according to claim 1, characterized in that: The solvent is one or a mixture of two of hexane, n-heptane, cyclohexane, pentane, petroleum ether and toluene.

4. The method according to claim 1, characterized in that: The molar ratio of butadiene to the iron element in the iron-based catalyst is (100-3000):

1.

5. The method according to claim 1, characterized in that The volume ratio of solvent to butadiene is (2.5-50):

1.

6. Bimodal polybutadiene obtained by the method according to any one of claims 1 to 5, characterized in that The content of trans-1,4 structure is 45-83%, the number average molecular weight of the low molecular weight part ranges from 0.5-220,000 g / mol, and the molecular weight distribution is 1.0-2.2, and the number average molecular weight of the high molecular weight part ranges from 800,000 to 4.6 million, and the molecular weight distribution is 1.0-2.

0.

7. Use of the bimodal polybutadiene prepared by the method according to any one of claims 1 to 5 in the preparation of high-performance tires.

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