Bridged transition metal-rare earth catalysts and methods for their preparation and modified rare earth butadiene rubbers and methods for their preparation

Abstract

This invention relates to the field of rare earth cis-butadiene rubber production, specifically disclosing a bridged transition metal-rare earth catalyst and its preparation method, as well as modified rare earth cis-butadiene rubber and its preparation method. The bridged transition metal-rare earth catalyst is made from rare earth neodymium organometallic compounds, transition metal organometallic compounds, alkyl metal compounds, organohalogen compounds, dicarboxylic acids, or diester compounds. The bridged transition metal-rare earth catalyst provided by this invention introduces transition metals and sterically hindered ligands to form a bridging structure with neodymium, reducing catalyst association. Simultaneously, a bimetallic synergistic effect exists, which is beneficial for improving catalyst utilization.

Description

Technical Field

[0001] This invention relates to the field of rare earth cis-butadiene rubber production, specifically to a bridging transition metal-rare earth catalyst and its preparation method, and a modified rare earth cis-butadiene rubber and its preparation method. Background Technology

[0002] Rare earth butadiene rubber (RIB) is the preferred raw material for green and high-performance tires. With the continued advancement of the EU tire labeling law, international tire companies' demand for RIB is steadily increasing, and domestic tire companies are also increasing their use of RIB to expand into international markets. However, existing RIB manufacturers' products are insufficient to meet market requirements regarding abrasion resistance, heat generation, and raw rubber stability.

[0003] Among numerous methods for preparing rare-earth butadiene rubber, the neodymium-based rare-earth catalyst method is simple and feasible. It can maintain high activity in the polymerization of conjugated dienes at very low catalyst concentrations, while obtaining linear polymers free of oligomers. Neodymium-based rare-earth catalysts can also provide a high degree of stereoregulation of the polymer, thus holding a crucial position and promising development prospects in catalyzing diene polymerization. However, neodymium ions have a high number of electrons and spatial unsaturation, and their derivatives readily interact with oxygen atoms in adjacent molecules to form oligomers. Intermolecular association leads to the formation of multiple active centers, inducing a broadening of the molecular weight distribution. Simultaneously, the high molecular weight of the oligomers results in higher catalyst viscosity, lower utilization of active centers, and a more complex and uncontrollable polymerization process.

[0004] Existing rare earth butadiene rubber catalytic systems typically employ ternary systems, including organic acid rare earth compounds, alkyl aluminum, and halogens. Utilizing ligands with large steric hindrance or strong electronegativity may allow neodymium ions to occupy space, reducing the probability of associated structures. However, ligand interactions are relatively weak, often requiring methods such as high-temperature reflux to form coordination during the preparation of organic acid neodymium. This process is complex and yields low results. Summary of the Invention

[0005] In view of this, the present invention proposes a method for preparing a bridged rare earth catalyst, which aims to reduce catalyst association by introducing a transition metal and a sterically hindered ligand to form a bridged structure with neodymium. At the same time, the synergistic effect of the two metals is beneficial to improving the catalyst utilization rate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a bridging transition metal-rare earth catalyst is provided, which is made of rare earth neodymium organometallic compounds, transition metal organometallic compounds, alkyl metal compounds, organohalogen compounds, dicarboxylic acids or diester compounds.

[0007] According to some embodiments of the present invention, the rare earth neodymium organic compound is one or more of rare earth neodymium carboxylates, rare earth neodymium acid phosphates, and rare earth neodymium acid phosphonates.

[0008] According to some embodiments of the present invention, the rare earth neodymium organic compound is one or more of neodymium neodecanoate, neodymium isooctanoate, neodymium naphthenate, neodymium di(2-ethylhexyl)phosphate, and neodymium mono-2-ethylhexyl phosphonate.

[0009] According to some embodiments of the present invention, the transition metal organometallic compound is one or more of nickel carboxylates, cobalt carboxylates, and ferric carboxylates.

[0010] According to some embodiments of the present invention, the transition metal organometallic compound is one or more of nickel neodecanoate, nickel isooctanoate, nickel naphthenate, cobalt neodecanoate, cobalt isooctanoate, cobalt naphthenate, iron neodecanoate, iron isooctanoate, and iron naphthenate.

[0011] According to some embodiments of the present invention, the alkyl metal compound is one or more of alkylaluminum compounds, alkyllithium compounds, and alkylmagnesium compounds.

[0012] According to some embodiments of the present invention, the alkyl metal compound is one or more selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, methyllithium, butyllithium, tert-butyllithium, and n-butylmagnesium.

[0013] According to some embodiments of the present invention, the organohalogen compound is one or more of alkylaluminum halohalogen, silane halohalogen, and sesquihaloalkylaluminum.

[0014] According to some embodiments of the present invention, the organohalogen compound is one or more of monochlorodiisobutylaluminum, monochlorodiethylaluminum, sesquiethylaluminum, and chloromethylsilane.

[0015] According to some embodiments of the present invention, the dicarboxylic acid or diester compound is one or more selected from succinic acid, dimethyl succinate, diethyl succinate, sebacic acid, dimethyl sebacic acid, diethyl sebacic acid, azelaic acid, dimethyl azelaic acid, and diethyl azelaic acid.

[0016] According to some embodiments of the present invention, the molar ratio of the rare earth neodymium organometallic compound, the transition metal organometallic compound, the alkyl metal compound, the organohalogen compound, and the dicarboxylic acid or diester compound is 1:(0.1-0.5):(3-16):(1-4):(0.1-0.5).

[0017] According to a second aspect of the present invention, a method for preparing a bridged transition metal-rare earth catalyst is provided, which is used to prepare the bridged transition metal-rare earth catalyst described in the first aspect of the present invention, the preparation method comprising the following steps: S1: Under the protection of an inert gas, rare earth neodymium organometallic compound, transition metal organometallic compound, dicarboxylic acid or diester compound are added to the first organic solvent, and the mixture is refluxed at the first temperature for the first time to obtain the first mixture; S2: Add an alkyl metal compound to the first mixture and age it at a second temperature for a second time to obtain a second mixture; S3: Add an organic halogen compound to the second mixture and age it at a third temperature for a third time to obtain the bridged transition metal-rare earth catalyst.

[0018] According to some embodiments of the present invention, in step S1, the first organic solvent is one or more of hexane, cyclohexane, n-heptane, hydrogenated gasoline, toluene, chlorotoluene, chlorobenzene, and dichlorotoluene.

[0019] According to some embodiments of the present invention, in step S1, the first temperature is 100-120°C and the first time is 120-240 min.

[0020] According to some embodiments of the present invention, in step S2, the second temperature is 50-90°C and the second time is 30-90 min.

[0021] According to some embodiments of the present invention, in step S3, the third temperature is 0-55°C and the third time is 30-120 min.

[0022] According to a third aspect of the present invention, a method for preparing modified rare earth cis-butadiene rubber is provided, wherein the butadiene monomer is polymerized by using the bridging transition metal-rare earth catalyst described in the first aspect of the present invention or the bridging transition metal-rare earth catalyst prepared by the preparation method described in the second aspect of the present invention to obtain modified rare earth cis-butadiene rubber.

[0023] According to some embodiments of the present invention, the preparation method of modified rare earth cis-butadiene rubber includes the following steps: S10: Under the protection of an inert gas, the butadiene monomer and the bridging transition metal-rare earth catalyst are added to the second organic solvent to carry out a polymerization reaction to obtain a polymerization reaction system; S20: Add a terminator to the polymerization reaction system to terminate the reaction and obtain the modified rare earth cis-butadiene rubber.

[0024] According to some embodiments of the present invention, the temperature of the polymerization reaction is 0-120°C, and the time of the polymerization reaction is 1-12 hours.

[0025] According to some embodiments of the present invention, the second organic solvent is one or more of hexane, cyclohexane, and hydrogenated gasoline.

[0026] According to some embodiments of the present invention, the molar ratio of the bridging transition metal-rare earth catalyst to the butadiene monomer is (1 × 10⁻⁶). -5 -0.9×10 -4 ):1.

[0027] According to some embodiments of the present invention, the volume ratio of the butadiene monomer to the second organic solvent is 0.2-1:1.

[0028] According to some embodiments of the present invention, in step S20, the terminating agent is an ethanol solution containing 2,6-di-tert-butyl-p-methylphenol.

[0029] According to some embodiments of the present invention, in step S20, after terminating the reaction, the product after terminating the reaction is subjected to subsequent processing, the subsequent processing including: adding excess water at 60-90°C to the product after terminating the reaction to coagulate a polymer; and drying the polymer to obtain the modified rare earth cis-butadiene rubber.

[0030] According to a fourth aspect of the present invention, a modified rare earth cis-butadiene rubber is provided, which is prepared by the preparation method described in the third aspect of the present invention.

[0031] By adopting the above technical solution, the present invention has at least the following beneficial technical effects: This invention utilizes dicarboxylic acid or diester compounds to bridge transition metals and rare earth metals, reducing the associated structure of rare earth catalysts, lowering the viscosity of organic acid rare earth compounds, and improving the utilization rate of rare earth catalysts. At the same time, there is a synergistic effect between transition metals and rare earth metals, resulting in higher catalyst activity and lower price compared to neodymium compounds.

[0032] The modified rare earth cis-butadiene rubber prepared using the bridging transition metal-rare earth catalyst provided by this invention has the characteristics of controllable structure, adjustable cis content, and adjustable molecular weight distribution. Its physical and mechanical properties are comparable to those of neodymium-based rare earth cis-butadiene rubber. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0034] Figure 1 A flowchart illustrating the preparation method of the bridged transition metal-rare earth catalyst provided by this invention; Figure 2 A flowchart illustrating the preparation method of the modified rare earth cis-butadiene rubber provided by this invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0036] According to a first aspect of the present invention, a bridging transition metal-rare earth catalyst is provided, which is made of rare earth neodymium organometallic compounds, transition metal organometallic compounds, alkyl metal compounds, organohalogen compounds, dicarboxylic acids or diester compounds.

[0037] This invention utilizes dicarboxylic acid or diester compounds to bridge transition metals and rare earth metals, reducing the associated structure of rare earth catalysts, lowering the viscosity of organic acid rare earth compounds, and improving the utilization rate of rare earth catalysts. Simultaneously, a bimetallic synergistic effect exists between the transition metal and the rare earth metal, resulting in catalyst activity that is higher than that of neodymium compounds, while at a lower cost. Specifically, this invention introduces a transition metal with sterically hindered organic acid ligands to form a bridging structure with neodymium, occupying the chemical environment surrounding neodymium and preventing the association of multiple neodymium active centers, thus improving neodymium utilization. The synergistic effect between the transition metal and the rare earth metal further enhances neodymium utilization, enabling the preparation of rare earth catalysts with higher activity.

[0038] In this invention, the rare earth neodymium organic compound is a type of compound in which neodymium is directly linked to an organic group. Preferably, the rare earth neodymium organic compound is one or more of rare earth neodymium carboxylates, rare earth neodymium acid phosphates, and rare earth neodymium acid phosphonates. More preferably, the rare earth neodymium organic compound is one or more of neodymium neodecanoate, neodymium isooctanoate, neodymium naphthenate, neodymium di(2-ethylhexyl) phosphate, and neodymium mono-2-ethylhexyl phosphonate.

[0039] In this invention, the organometallic transition metal compound is a type of compound in which a transition metal element (such as iron, cobalt, nickel, etc.) is directly bonded to an organic group. Preferably, the organometallic transition metal compound is one or more of nickel carboxylates, cobalt carboxylates, and ferric carboxylates. More preferably, the organometallic transition metal compound is one or more of nickel neodecanoate, nickel isooctanoate, nickel naphthenate, cobalt neodecanoate, cobalt isooctanoate, cobalt naphthenate, iron neodecanoate, iron isooctanoate, and iron naphthenate.

[0040] In this invention, the alkyl metal compound is a class of compounds containing an alkyl group (such as methyl, ethyl, propyl, butyl, etc.) bonded to a metal atom. Preferably, the alkyl metal compound is one or more of alkylaluminum compounds, alkyllithium compounds, and alkylmagnesium compounds. More preferably, the alkyl metal compound is one or more of trimethylaluminum, triethylaluminum, triisobutylaluminum, methyllithium, butyllithium, tert-butyllithium, and n-butylmagnesium.

[0041] In this invention, the organohalogen compound, also known as a halogenated organic compound, is an organic compound containing halogen atoms. Preferably, the organohalogen compound is one or more selected from alkylaluminum halohalogen, silane halohalogen, and sesquihaloalkylaluminum. More preferably, the organohalogen compound is one or more selected from diisobutylaluminum chloride, diethylaluminum chloride, sesquiethylaluminum, and chloromethylsilane.

[0042] In this invention, the dicarboxylic acid or diester compound is a class of compounds containing two carboxylic acid groups and two alkyl ester groups. Their structural characteristic is that two long carbon chains (alkyl groups) are linked together by the carboxylic acid groups to form an ester structure. Preferably, the dicarboxylic acid or diester compound is one or more of the following: succinic acid, dimethyl succinate, diethyl succinate, sebacic acid, dimethyl sebacic acid, diethyl sebacic acid, azelaic acid, dimethyl azelaic acid, and diethyl azelaic acid.

[0043] In some embodiments, the molar ratio of rare earth neodymium organometallic compounds, transition metal organometallic compounds, alkyl metal compounds, organohalogen compounds, dicarboxylic acid compounds, or diester compounds is 1:(0.1-0.5):(3-16):(1-4):(0.1-0.5).

[0044] According to a second aspect of the present invention, a method for preparing the above-mentioned bridging transition metal-rare earth catalyst is provided, such as... Figure 1 As shown, the preparation method includes the following steps: S1: Under inert gas protection, rare earth neodymium organometallic compound, transition metal organometallic compound, dicarboxylic acid or diester compound are added to a first organic solvent, and the mixture is refluxed at a first temperature for a first time to obtain a first mixture; S2: An alkyl metal compound is added to the first mixture, and the mixture is aged at a second temperature for a second time to obtain a second mixture; S3: An organohalogen compound is added to the second mixture, and the mixture is aged at a third temperature for a third time to obtain a bridged transition metal-rare earth catalyst.

[0045] In some embodiments, in step S1, the first organic solvent is one or more of hexane, cyclohexane, n-heptane, hydrogenated gasoline, toluene, chlorotoluene, chlorobenzene, and dichlorotoluene.

[0046] In some embodiments, in step S1, the first temperature is 100-120°C, and the first time is 120-240 min. For example, the first temperature can typically, but not limited to, be set to 100°C, 105°C, 110°C, 115°C, 120°C, etc.; the first time can typically, but not limited to, be set to 120 min, 150 min, 180 min, 210 min, 240 min, etc.

[0047] In some embodiments, in step S2, the second temperature is 50-90°C and the second time is 30-90 min. For example, the second temperature can typically, but not limitedly, be set to 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, etc.; and the second time can typically, but not limitedly, be set to 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, etc.

[0048] In some embodiments, in step S3, the third temperature is 0-55°C, and the third time is 30-120 min. For example, the third temperature can typically, but not limitedly, be set to 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, etc.; the third time can typically, but not limitedly, be set to 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, etc.

[0049] In some embodiments, the inert gas is nitrogen.

[0050] In a specific example, under nitrogen protection, a first organic solvent, selected from one of the following saturated alkanes: hexane, cyclohexane, n-heptane, hydrogenated gasoline, toluene, chlorotoluene, chlorobenzene, and dichlorotoluene, is added to a dry catalyst aging reactor. Rare earth neodymium organic compounds, transition metal organometallic compounds, and dicarboxylic acid or diester compounds are added sequentially according to the specified ratio. The mixture is refluxed at 100-120°C for 120-240 min. An alkyl metal compound is then added, and the mixture is aged at 50-90°C for 30-90 min. Finally, an organic halogen compound is added, and the mixture is aged at 0-55°C for 30-120 min to obtain a bridged transition metal-rare earth catalyst.

[0051] According to a third aspect of the present invention, a method for preparing modified rare earth cis-butadiene rubber is provided, wherein the butadiene monomer is polymerized by using the bridging transition metal-rare earth catalyst described in the first aspect of the present invention or the bridging transition metal-rare earth catalyst prepared by the preparation method described in the second aspect of the present invention to obtain modified rare earth cis-butadiene rubber.

[0052] The rare earth cis-butadiene rubber prepared by the method of the present invention has more easily controllable structural properties and is easier to obtain products with more special performance advantages. At the same time, the prepared rare earth cis-butadiene rubber has adjustable cis content and molecular weight distribution, and its physical and mechanical properties are similar to those of neodymium-based rare earth cis-butadiene rubber, overcoming the shortcomings of high cost of existing rare earth neodymium catalytic systems.

[0053] In some embodiments, such as Figure 2 As shown, the preparation method of modified rare earth cis-butadiene rubber includes the following steps: S10: Under the protection of inert gas, butadiene monomer and bridging transition metal-rare earth catalyst are added to the second organic solvent to carry out a polymerization reaction to obtain a polymerization reaction system; S20: A terminator is added to the polymerization reaction system to terminate the reaction to obtain modified rare earth cis-butadiene rubber.

[0054] In some embodiments, the polymerization temperature is 0-120°C, and the polymerization time is 1-12 hours. For example, the polymerization temperature can typically, but not limitedly, be set to 0°C, 20°C, 40°C, 60°C, 80°C, 100°C, 120°C, etc.; and the polymerization time can typically, but not limitedly, be set to 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, etc.

[0055] In some embodiments, the second organic solvent is one or more of hexane, cyclohexane, and hydrogenated gasoline.

[0056] In some embodiments, the molar ratio of the bridged transition metal-rare earth catalyst to the butadiene monomer is (1×10⁻⁶). -5 -0.9×10 -4 ):1.

[0057] In some embodiments, the volume ratio of butadiene monomer to the second organic solvent is 0.2-1:1.

[0058] In some embodiments, in step S20, the terminating agent is an ethanol solution containing 2,6-di-tert-butyl-p-methylphenol. For example, the terminating agent is an ethanol solution containing 1% by mass of 2,6-di-tert-butyl-p-methylphenol.

[0059] In some embodiments, in step S20, after terminating the reaction, the product after the termination reaction is subjected to further processing, which includes: adding excess hot water to the product after the termination reaction to coagulate a polymer; and drying the polymer to obtain modified rare earth cis-butadiene rubber. Preferably, the temperature of the hot water is 60-90°C.

[0060] In some embodiments, the inert gas is nitrogen.

[0061] In a specific example, under nitrogen protection, a second organic solvent and butadiene monomer are added to a dried and deoxygenated polymerization reactor according to the specified ratio. The second organic solvent is selected from one of the saturated alkanes, such as hexane, cyclohexane, and hydrogenated gasoline. Then, a bridging transition metal-rare earth catalyst is added, and the reaction is carried out at 0-120°C for 1-12 hours. The reaction is terminated with an ethanol solution containing 1% by mass of 2,6-di-tert-butyl-p-methylphenol. The polymer is coagulated with excess hot water and then repeatedly squeezed and dried by hot rolling to obtain modified rare earth cis-butadiene rubber.

[0062] According to a fourth aspect of the present invention, a modified rare earth cis-butadiene rubber is provided, which is prepared by the preparation method described in the third aspect of the present invention.

[0063] The present invention will now be described in detail with reference to specific embodiments.

[0064] In this invention, the modified rare earth cis-butadiene rubber is evaluated after vulcanization: Preparation method of modified rare earth butadiene rubber vulcanizate samples: The basic formula is as follows: 100 parts (by weight, the same below) of modified rare earth butadiene rubber (Nd-BR), 4 parts of zinc oxide, 3 parts of stearic acid, 50 parts of carbon black, 20 parts of processing oil, 1.0 part of accelerator TBBS, and 1.8 parts of sulfur. First, on a two-roll mill, Nd-BR, zinc oxide, stearic acid, carbon black, processing oil, sulfur, and accelerator TBBS are added sequentially. The roll temperature is adjusted to 35±5℃, and the roll gap is 0.45±0.1mm. After uniform mixing, the mixture is sheeted and then left to stand at room temperature for 24 hours. Vulcanization is then performed on a flat vulcanizing machine under the following conditions: 145℃×35min×10MPa. The vulcanized samples are cut into dumbbell-shaped tensile test strips according to GB / T528-2009.

[0065] Physical and mechanical property testing: The tensile strength, 300% constant elongation stress and elongation at break of the vulcanizate were tested using a tensile testing machine.

[0066] Microstructure content: The FTIR spectra of Nd-BR were measured using a Fourier transform infrared spectroscopy (FTIR) instrument, and the contents of cis structure, trans structure, and 1,2 structure of Nd-BR were calculated.

[0067] Relative molecular mass and its distribution: Mn, Mw, and Mw / Mn of the sample were determined by gel permeation chromatography. Tetrahydrofuran was used as the mobile phase, the test temperature was 30℃, the flow rate was 1.0 mL / min, and a standard curve was established using polystyrene standards.

[0068] Mooney viscosity: Mooney viscosity was tested using a Mooney viscometer according to standard GB / T1232.1-2016. A large rotor was used, and the test was conducted for 4 minutes after preheating. The test temperature was 100℃.

[0069] Aging performance was determined according to GB / T 3512-2014 Accelerated aging and heat resistance test of vulcanized rubber or thermoplastic rubber in hot air.

[0070] Example 1 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of toluene, 2.5 mL of hexane solution containing neodymium neodecanoate (0.11 mmol), 2.5 mL of hexane solution containing nickel isooctanoate (0.06 mmol), and 8.5 mL of toluene solution containing dimethyl octanoate (0.06 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 100 °C for 240 min. Then, 5.5 mL of hexane solution containing triisobutylaluminum (1.78 mmol) was added, and the mixture was reacted at 60 °C for 90 min. Finally, 2.0 mL of hexane solution containing diisobutylaluminum chloride (0.44 mmol) was added, and the mixture was reacted at 0 °C for 120 min.

[0071] Preparation of modified rare earth cis-butadiene rubber: 3600 mL of butadiene-hexane solution containing 600 mL of butadiene was added to a 5000 mL polymerization reactor. Then, the bridged transition metal-rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.1 × 10⁻⁶) was added. -4 :1), Stir and react at 120℃ for 1 hour. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0072] The product results are as follows: product conversion rate 96%; cis-1,4-polybutadiene content (mass percentage) 96.5%, trans-1,4-polybutadiene content (mass percentage) 2%, 1,2-polybutadiene content (mass percentage) 1.5%; weight-average molecular weight 28 × 10⁻⁶. 4 The molecular weight distribution is 2.21; Mooney (ML1+4, 100℃): 43MU.

[0073] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 463%, tensile strength 20.1 MPa, 300% elongation 11.3 MPa.

[0074] Example 2 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of n-heptane, 2.5 mL of n-hexane solution containing neodymium isooctanoate (0.11 mmol), 2.5 mL of n-hexane solution containing nickel naphthenate (0.04 mmol), and 6.5 mL of toluene solution containing octanoic acid (0.04 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 120 °C for 120 min. Then, 4.0 mL of n-hexane solution containing triethylaluminum (0.44 mmol) was added, and the mixture was reacted at 90 °C for 60 min. Finally, 2.5 mL of n-hexane solution containing diethylaluminum chloride (0.22 mmol) was added, and the mixture was reacted at 55 °C for 30 min.

[0075] Preparation of modified rare earth cis-butadiene rubber: 1800 mL of butadiene-hexane solution containing 300 mL of butadiene was added to a 5000 mL polymerization reactor, followed by the addition of the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.2 × 10⁻⁶). -4 :1), Stir and react at 0℃ for 12 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0076] The product results are as follows: product conversion rate 89%; cis-1,4-polybutadiene content (mass percentage) 97.1%, trans-1,4-polybutadiene content (mass percentage) 1.5%, 1,2-polybutadiene content (mass percentage) 1.4%; weight-average molecular weight 43 × 10⁻⁶. 4 The molecular weight distribution is 2.01; Mooney (ML1+4, 100℃): 67MU.

[0077] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 490%, tensile strength 22.5 MPa, 300% elongation 12.5 MPa.

[0078] Example 3 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of n-hexane, 3.5 mL of n-hexane solution containing neodymium di(2-ethylhexyl) phosphate (0.67 mmol), 4.5 mL of n-hexane solution containing nickel neodecanoate (0.13 mmol), and 5.5 mL of toluene solution containing diethyl octanoate (0.13 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 110 °C for 180 min, then 8.0 mL of n-hexane solution containing butyllithium (5.33 mmol) was added, and the mixture was reacted at 80 °C for 80 min. Finally, 3.0 mL of n-hexane solution containing sesquiethylaluminum (2.0 mmol) was added, and the mixture was reacted at 0 °C for 120 min.

[0079] Preparation of modified rare earth cis-butadiene rubber: 800 mL of butadiene-hexane solution containing 400 mL of butadiene was added to a 5000 mL polymerization reactor. Then, the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.9 × 10⁻⁶) was added. -4 :1) Stir and react at 50℃ for 6 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0080] The product results are as follows: product conversion rate 93%; cis-1,4-polybutadiene content (mass percentage) 95.5%, trans-1,4-polybutadiene content (mass percentage) 3.2%, 1,2-polybutadiene content (mass percentage) 1.3%; weight-average molecular weight 31 × 10⁻⁶. 4 The molecular weight distribution is 2.43; Mooney (ML1+4, 100℃): 47MU.

[0081] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 440%, tensile strength 19.3 MPa, 300% elongation 10.1 MPa.

[0082] Example 4 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of chlorobenzene, 4.0 mL of n-hexane solution containing neodymium mono-2-ethylhexyl phosphonate (0.74 mmol), 2.5 mL of n-hexane solution containing cobalt neodecanoate (0.07 mmol), and 4.5 mL of toluene solution containing sebacic acid (0.07 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 100 °C for 150 min, then 5.5 mL of n-hexane solution containing lithium methyl (3.70 mmol) was added, and the mixture was reacted at 50 °C for 40 min. Finally, 3.0 mL of n-hexane solution containing chloromethylsilane (1.85 mmol) was added, and the mixture was reacted at 20 °C for 90 min.

[0083] Preparation of modified rare earth cis-butadiene rubber: 2800 mL of butadiene-hexane solution containing 800 mL of butadiene was added to a 5000 mL polymerization reactor. Then, the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.5 × 10⁻⁶) was added. -4 :1), Stir and react at 100℃ for 8 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0084] The product results are as follows: product conversion rate 92%; cis-1,4-polybutadiene content (mass percentage) 96.3%, trans-1,4-polybutadiene content (mass percentage) 2.3%, 1,2-polybutadiene content (mass percentage) 1.4%; weight-average molecular weight 26 × 10⁻⁶. 4 The molecular weight distribution is 2.11; Mooney (ML1+4, 100℃): 43MU.

[0085] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 415%, tensile strength 18.7 MPa, 300% elongation 12.4 MPa.

[0086] Example 5 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of hydrogenated gasoline, 5.0 mL of hexane solution containing neodymium naphthenate (0.30 mmol), 3.5 mL of hexane solution containing cobalt isooctanoate (0.15 mmol), and 3.5 mL of toluene solution containing dimethyl sebacate (0.15 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 105 °C for 200 min. Then, 3.5 mL of hexane solution containing n-butylmagnesium (2.07 mmol) was added, and the mixture was reacted at 60 °C for 50 min. Finally, 2.0 mL of hexane solution containing chloromethylsilane (0.95 mmol) was added, and the mixture was reacted at 55 °C for 120 min.

[0087] Preparation of modified rare earth cis-butadiene rubber: 1400 mL of butadiene-hexane solution containing 400 mL of butadiene was added to a 5000 mL polymerization reactor. Then, the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.4 × 10⁻⁶) was added. -4 :1), Stir and react at 40℃ for 5 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0088] The product results are as follows: product conversion rate 90%; cis-1,4-polybutadiene content (mass percentage) 98.2%, trans-1,4-polybutadiene content (mass percentage) 0.5%, 1,2-polybutadiene content (mass percentage) 1.3%; weight-average molecular weight 23 × 10⁻⁶. 4 The molecular weight distribution is 2.05; Mooney (ML1+4, 100℃): 41MU.

[0089] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): Elongation at break 422%, tensile strength 19.5 MPa, 300% elongation 11.3 MPa.

[0090] Example 6 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of dichlorotoluene, 7.0 mL of a hexane solution containing a mixture of neodymium naphthenate and isooctanoic acid (molar ratio 1:1) (0.44 mmol), 6.5 mL of a hexane solution containing cobalt naphthenate (0.22 mmol), and 4.5 mL of a toluene solution containing diethyl sebacate (0.22 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 115 °C for 210 min, then 8.5 mL of a hexane solution containing n-butylmagnesium (4.44 mmol) was added, and the mixture was reacted at 60 °C for 30 min. Finally, 3.0 mL of a hexane solution containing chloromethylsilane (0.44 mmol) was added, and the mixture was reacted at 55 °C for 90 min.

[0091] Preparation of modified rare earth cis-butadiene rubber: 1733 mL of butadiene-hexane solution containing 400 mL of butadiene was added to a 5000 mL polymerization reactor, followed by the addition of the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.6 × 10⁻⁶). -4 :1), Stir and react at 90℃ for 12 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0092] The product results are as follows: product conversion rate 89%; cis-1,4-polybutadiene content (mass percentage) 94.2%, trans-1,4-polybutadiene content (mass percentage) 3.8%, 1,2-polybutadiene content (mass percentage) 2.0%; weight-average molecular weight 41 × 10⁻⁶. 4 The molecular weight distribution is 1.88; Mooney (ML1+4, 100℃): 53MU.

[0093] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 417%, tensile strength 22.5 MPa, 300% elongation 12.1 MPa.

[0094] Example 7 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of cyclohexane, 5.0 mL of n-hexane solution containing a mixture of neodymium mono-2-ethylhexyl phosphonate and neodymium neodecanoate (molar ratio 2:3) (1.03 mmol), 5.5 mL of n-hexane solution containing ferric naphthenate (0.41 mmol), and 8.5 mL of toluene solution containing a mixture of sebacic acid and octanoic acid (molar ratio 3:5) (0.41 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 110 °C for 130 min, 8.0 mL of n-hexane solution containing trimethylaluminum (5.19 mmol) was added, and the reaction was carried out at 50 °C for 75 min. Then, 4.0 mL of n-hexane solution containing diisobutylaluminum chloride (2.60 mmol) was added, and the reaction was carried out at 30 °C for 100 min.

[0095] Preparation of modified rare earth cis-butadiene rubber: 2400 mL of butadiene-hexane solution containing 800 mL of butadiene was added to a 5000 mL polymerization reactor. Then, the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.7 × 10⁻⁶) was added. -4 :1), Stir and react at 60℃ for 10 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0096] The product results are as follows: product conversion rate 85%; cis-1,4-polybutadiene content (mass percentage) 96.1%, trans-1,4-polybutadiene content (mass percentage) 2.3%, 1,2-polybutadiene content (mass percentage) 1.6%; weight-average molecular weight 31 × 10⁻⁶. 4 The molecular weight distribution is 2.53; Mooney (ML1+4, 100℃): 51MU.

[0097] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 427%, tensile strength 16.5 MPa, 300% elongation 10.7 MPa.

[0098] Example 8 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of chlorotoluene, 6.0 mL of hexane solution containing neodymium neodecanoate (0.37 mmol), 5.5 mL of hexane solution containing ferric isooctanoate (0.11 mmol), and 8.5 mL of toluene solution containing azelaic acid (0.11 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 105 °C for 160 min. Then, 9.5 mL of hexane solution containing triisobutylaluminum (1.11 mmol) was added, and the mixture was reacted at 65 °C for 70 min. Finally, 5.0 mL of hexane solution containing diisobutylaluminum monochloro (1.115 mmol) was added, and the mixture was reacted at 50 °C for 60 min.

[0099] Preparation of modified rare earth cis-butadiene rubber: 3600 mL of butadiene-hexane solution containing 600 mL of butadiene was added to a 5000 mL polymerization reactor. Then, the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.4 × 10⁻⁶) was added. -4 :1), Stir and react at 120℃ for 7 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0100] The product results are as follows: product conversion rate 85%; cis-1,4-polybutadiene content (mass percentage) 92.1%, trans-1,4-polybutadiene content (mass percentage) 2.6%, 1,2-polybutadiene content (mass percentage) 5.3%; weight-average molecular weight 29 × 10⁻⁶. 4 The molecular weight distribution is 2.53; Mooney (ML1+4, 100℃): 49MU.

[0101] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 517%, tensile strength 22.8 MPa, 300% elongation 13.3 MPa.

[0102] Example 9 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of dichlorotoluene, 8.0 mL of hexane solution containing neodymium isooctanoate (0.74 mmol), 4.5 mL of hexane solution containing ferric neodecanoate (0.37 mmol), and 7.5 mL of toluene solution containing a mixture of azelaic acid and dimethyl azelate (molar ratio 5:2) (0.37 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 105 °C for 140 min, then 9.5 mL of hexane solution containing triisobutylaluminum (5.93 mmol) was added, and the mixture was reacted at 80 °C for 30 min. Finally, 3.0 mL of hexane solution containing diisobutylaluminum monochloro (2.60 mmol) was added, and the mixture was reacted at 40 °C for 40 min.

[0103] Preparation of modified rare earth cis-butadiene rubber: 1333 mL of butadiene-hexane solution containing 500 mL of butadiene was added to a 5000 mL polymerization reactor, followed by the addition of the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.8 × 10⁻⁶). -4 :1), Stir and react at 100℃ for 4 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0104] The product results are as follows: product conversion rate 95%; cis-1,4-polybutadiene content (mass percentage) 90.7%, trans-1,4-polybutadiene content (mass percentage) 2.0%, 1,2-polybutadiene content (mass percentage) 7.3%; weight-average molecular weight 36 × 10⁻⁶. 4 The molecular weight distribution is 2.13; Mooney (ML1+4, 100℃): 61MU.

[0105] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 527%, tensile strength 23.5 MPa, 300% elongation 13.9 MPa.

[0106] Example 10 Preparation of bridged transition metal-rare earth catalysts: At room temperature, 100 mL of n-hexane, 10.0 mL of n-hexane solution containing neodymium mono-2-ethylhexyl phosphonate (0.15 mmol), 6.5 mL of n-hexane solution containing a mixture of iron neodecanoate and nickel neodecanoate (molar ratio 2:3) (0.07 mmol), and 6.5 mL of toluene solution containing a mixture of octanoic acid and diethyl azelate (molar ratio 3:2) (0.07 mmol) were added sequentially to a 500 mL catalyst aging flask. The mixture was refluxed at 110 °C for 200 min, then 9.5 mL of n-hexane solution containing triisobutylaluminum (1.63 mmol) was added, and the mixture was reacted at 60 °C for 30 min. Finally, 5.0 mL of n-hexane solution containing diisobutylaluminum monochloro (0.44 mmol) was added, and the mixture was reacted at 40 °C for 40 min.

[0107] Preparation of modified rare earth cis-butadiene rubber: 2133 mL of butadiene-hexane solution containing 800 mL of butadiene was added to a 5000 mL polymerization reactor, followed by the addition of the rare earth catalyst prepared above (Nd / butadiene molar ratio of 0.1 × 10⁻⁶). -4 :1), Stir and react at 90℃ for 6 hours. After the reaction is complete, transfer the rubber solution from the reactor to an enamel tank containing high-temperature hot water for cooking. After repeated rolling on a two-roll mill, modified rare earth cis-butadiene rubber is obtained.

[0108] The product results are as follows: product conversion rate 99%; cis-1,4-polybutadiene content (mass percentage) 96.1%, trans-1,4-polybutadiene content (mass percentage) 0.8%, 1,2-polybutadiene content (mass percentage) 3.1%; weight-average molecular weight 23 × 10⁻⁶. 4 The molecular weight distribution is 3.15; Mooney (ML1+4, 100℃): 49MU.

[0109] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 453%, tensile strength 21.3 MPa, 300% elongation 12.1 MPa.

[0110] Example 11 The preparation of the bridging transition metal-rare earth catalyst is the same as in Example 10, except that the transition metal organometallic compound used is iron neodecanoate.

[0111] The preparation of modified rare earth cis-butadiene rubber is the same as in Example 10.

[0112] The product results are as follows: product conversion rate 95%; cis-1,4-polybutadiene content (mass percentage) 93.2%, trans-1,4-polybutadiene content (mass percentage) 1.1%, 1,2-polybutadiene content (mass percentage) 5.7%; weight-average molecular weight 26 × 10⁻⁶. 4 The molecular weight distribution is 1.93; Mooney (ML1+4, 100℃): 41MU.

[0113] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 537%, tensile strength 21.7 MPa, 300% elongation 13.7 MPa.

[0114] Example 12 The preparation of the bridging transition metal-rare earth catalyst is the same as in Example 5, except that the molar ratio of cobalt isooctanoate to neodymium naphthenate is 0.1:1.

[0115] The preparation of modified rare earth cis-butadiene rubber is the same as in Example 5.

[0116] The product results are as follows: product conversion rate 82%; cis-1,4-polybutadiene content (mass percentage) 97.7%, trans-1,4-polybutadiene content (mass percentage) 1.2%, 1,2-polybutadiene content (mass percentage) 1.1%; weight-average molecular weight 34 × 10⁻⁶. 4 The molecular weight distribution is 2.63; Mooney (ML1+4, 100℃): 67MU.

[0117] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): Elongation at break 457%, tensile strength 21.7 MPa, 300% elongation 12.1 MPa.

[0118] Comparative Example 1 The catalyst preparation process is the same as in Example 1, except that nickel isooctanoate was not added.

[0119] The preparation process of rare earth cis-butadiene rubber is the same as in Example 1.

[0120] The product results are as follows: product conversion rate was 41%; the mass percentage of cis-1,4-polybutadiene was 97.2%, the mass percentage of trans-1,4-polybutadiene was 1.2%, and the mass percentage of 1,2-polybutadiene was 0.6%; the weight-average molecular weight was 41 × 10⁻⁶. 4 The molecular weight distribution is 2.01; Mooney (ML1+4, 100℃): 64MU.

[0121] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 422%, tensile strength 18.7 MPa, 300% elongation 10.1 MPa.

[0122] The results of Comparative Example 1 and the Examples show that the activity of the catalytic system is significantly reduced without the addition of transition metal organometallic compounds.

[0123] Comparative Example 2 The catalyst preparation process is the same as in Example 2, except that octanoic acid was not added.

[0124] The preparation process of rare earth cis-butadiene rubber is the same as in Example 2.

[0125] The product results are as follows: product conversion rate 68%; cis-1,4-polybutadiene content by mass percentage 96.3%, trans-1,4-polybutadiene content by mass percentage 1.2%, and 1,2-polybutadiene content by mass percentage 1.5%; weight-average molecular weight 27 × 10⁻⁶. 4 The molecular weight distribution is 2.31; Mooney (ML1+4, 100℃): 45MU.

[0126] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 477%, tensile strength 22.1 MPa, 300% elongation 12.4 MPa.

[0127] The results from Comparative Example 2 and Example 2 show that the activity of the catalytic system decreases when no dicarboxylic acid or diester compound is added.

[0128] Comparative Example 3 Preparation of neodymium catalysts: At room temperature, 100 mL of n-hexane, 5.5 mL of n-hexane solution containing triethylaluminum (2.0 mmol), and 3.0 mL of n-hexane solution containing neodymium isooctanoate (0.11 mmol) were added sequentially to a 500 mL catalyst aging flask. After aging at 60 °C for 90 min, 2.0 mL of n-hexane solution containing diethylaluminum chloride (0.22 mmol) was added, and the reaction was carried out at 0 °C for 120 min.

[0129] The preparation process of rare earth cis-butadiene rubber is the same as in Example 2.

[0130] The product results are as follows: product conversion rate 93%; cis-1,4-polybutadiene content (mass percentage) 97.9%, trans-1,4-polybutadiene content (mass percentage) 1.7%, 1,2-polybutadiene content (mass percentage) 0.4%; weight-average molecular weight 22 × 10⁻⁶. 4 The molecular weight distribution is 2.05; Mooney (ML1+4, 100℃): 41MU.

[0131] Physical and mechanical properties of vulcanized rubber (35 min vulcanization time): elongation at break 433%, tensile strength 19.7 MPa, 300% elongation 10.1 MPa.

[0132] The results of Comparative Example 3 and Example 2 show that a larger amount of alkylating agent is needed to maintain a high conversion rate in the pure neodymium neodecanoate system.

[0133] Comparative Example 4 The catalyst preparation process is the same as in Example 3, except that neodymium di(2-ethylhexyl) phosphate was not added.

[0134] The preparation process of rare earth cis-butadiene rubber is the same as in Example 3.

[0135] The product results are as follows: product conversion rate 17%; cis-1,4-polybutadiene content (mass percentage) 91.2%, trans-1,4-polybutadiene content (mass percentage) 6.3%, 1,2-polybutadiene content (mass percentage) 2.5%; weight-average molecular weight 8 × 10⁻⁶. 4 The molecular weight distribution is 3.13; Mooney (ML1+4, 100℃): 13MU.

[0136] The results of Comparative Example 4 and Example 3 show that the catalytic activity is extremely low without the addition of rare earth neodymium organic compounds.

[0137] In summary, the bridged transition metal-rare earth catalyst prepared by the method of this invention reduces the association structure of the rare earth catalyst, improves the utilization rate of the rare earth catalyst, exhibits bimetallic synergistic effect, has higher catalyst activity than neodymium compounds, and is cheaper. At the same time, the cis content is adjustable, and the physical and mechanical properties are comparable to neodymium-based rare earth cis-butadiene rubber.

[0138] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

[0139] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A bridging transition metal-rare earth catalyst, characterized in that, It is made from rare earth neodymium organometallic compounds, transition metal organometallic compounds, alkyl metal compounds, organohalogen compounds, dicarboxylic acids or diester compounds.

2. The bridging transition metal-rare earth catalyst according to claim 1, characterized in that, The rare earth neodymium organic compound is one or more of rare earth neodymium carboxylates, rare earth neodymium acid phosphates, and rare earth neodymium acid phosphonates.

3. The bridging transition metal-rare earth catalyst according to claim 2, characterized in that, The rare earth neodymium organic compound is one or more of neodymium neodecanoate, neodymium isooctanoate, neodymium naphthenate, neodymium di(2-ethylhexyl) phosphate, and neodymium mono-2-ethylhexyl phosphonate.

4. The bridging transition metal-rare earth catalyst according to claim 1, characterized in that, The transition metal organometallic compound is one or more of nickel carboxylates, cobalt carboxylates, and ferric carboxylates.

5. The bridging transition metal-rare earth catalyst according to claim 4, characterized in that, The transition metal organometallic compound is one or more of nickel neodecanoate, nickel isooctanoate, nickel naphthenate, cobalt neodecanoate, cobalt isooctanoate, cobalt naphthenate, iron neodecanoate, iron isooctanoate, and iron naphthenate.

6. The bridging transition metal-rare earth catalyst according to claim 1, characterized in that, The alkyl metal compound is one or more of alkylaluminum compounds, alkyllithium compounds, and alkylmagnesium compounds.

7. The bridging transition metal-rare earth catalyst according to claim 6, characterized in that, The alkyl metal compound is one or more selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, methyllithium, butyllithium, tert-butyllithium, and n-butylmagnesium.

8. The bridging transition metal-rare earth catalyst according to claim 1, characterized in that, The organohalogen compound is one or more of alkylaluminum halo, silane halo, and sesquihaloalkylaluminum.

9. The bridging transition metal-rare earth catalyst according to claim 8, characterized in that, The organohalogen compound is one or more of monochlorodiisobutylaluminum, monochlorodiethylaluminum, sesquiethylaluminum, and chloromethylsilane.

10. The bridging transition metal-rare earth catalyst according to claim 1, characterized in that, The dicarboxylic acid or diester compound is one or more of the following: succinic acid, dimethyl succinate, diethyl succinate, sebacic acid, dimethyl sebacic acid, diethyl sebacic acid, azelaic acid, dimethyl azelaic acid, and diethyl azelaic acid.

11. The bridging transition metal-rare earth catalyst according to any one of claims 1-10, characterized in that, The molar ratio of the rare earth neodymium organometallic compound, the transition metal organometallic compound, the alkyl metal compound, the organohalogen compound, and the dicarboxylic acid or diester compound is 1:(0.1-0.5):(3-16):(1-4):(0.1-0.5).

12. A method for preparing a bridging transition metal-rare earth catalyst, characterized in that, The preparation method for the bridged transition metal-rare earth catalyst according to any one of claims 1-11 comprises the following steps: S1: Under the protection of an inert gas, rare earth neodymium organometallic compound, transition metal organometallic compound, dicarboxylic acid or diester compound are added to the first organic solvent, and the mixture is refluxed at the first temperature for the first time to obtain the first mixture; S2: Add an alkyl metal compound to the first mixture and age it at a second temperature for a second time to obtain a second mixture; S3: Add an organic halogen compound to the second mixture and age it at a third temperature for a third time to obtain the bridged transition metal-rare earth catalyst.

13. The method for preparing the bridging transition metal-rare earth catalyst according to claim 12, characterized in that, In step S1, the first organic solvent is one or more of hexane, cyclohexane, n-heptane, hydrogenated gasoline, toluene, chlorotoluene, chlorobenzene, and dichlorotoluene.

14. The method for preparing the bridging transition metal-rare earth catalyst according to claim 12, characterized in that: In step S1, the first temperature is 100-120℃ and the first time is 120-240min; In step S2, the second temperature is 50-90℃ and the second time is 30-90min; In step S3, the third temperature is 0-55℃ and the third time is 30-120min.

15. A method for preparing modified rare earth cis-butadiene rubber, characterized in that, Modified rare earth cis-butadiene rubber is obtained by using the bridged transition metal-rare earth catalyst according to any one of claims 1-11 or the bridged transition metal-rare earth catalyst prepared by any one of claims 12-14 to catalyze the polymerization reaction of butadiene monomer.

16. The method for preparing modified rare earth cis-butadiene rubber according to claim 15, characterized in that, The preparation method includes the following steps: S10: Under the protection of an inert gas, the butadiene monomer and the bridging transition metal-rare earth catalyst are added to the second organic solvent to carry out a polymerization reaction to obtain a polymerization reaction system; S20: A terminator is added to the polymerization reaction system to terminate the reaction and obtain the modified rare earth cis-butadiene rubber.

17. The method for preparing modified rare earth cis-butadiene rubber according to claim 15 or 16, characterized in that, The polymerization reaction is carried out at a temperature of 0-120°C for 1-12 hours.

18. The method for preparing modified rare earth cis-butadiene rubber according to claim 16, characterized in that, The second organic solvent is one or more of hexane, cyclohexane, and hydrogenated gasoline.

19. The method for preparing modified rare earth cis-butadiene rubber according to claim 16, characterized in that, The molar ratio of the bridging transition metal-rare earth catalyst to the butadiene monomer is (1×10⁻⁶). -5 -0.9×10 -4 The volume ratio of the butadiene monomer to the second organic solvent is 0.2-1:

1.

20. The method for preparing modified rare earth cis-butadiene rubber according to claim 16, characterized in that, In step S20, the terminator is an ethanol solution containing 2,6-di-tert-butyl-p-methylphenol. After terminating the reaction, the product after the termination reaction is subjected to subsequent processing, which includes: adding excess water at 60-90°C to the product after the termination reaction to coagulate the polymer; and drying the polymer to obtain the modified rare earth cis-butadiene rubber.

21. A modified rare earth cis-butadiene rubber, characterized in that, It is prepared by any one of the preparation methods according to claims 15-20.

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