STAR-BRANCHING FORMING AGENT, METHODS OF PREPARATION, LONG-CHAIN ​​BUTADIENE RUBBER, METHODS OF PRODUCTION AND TIRES

Abstract

The invention relates to a functionalized star-shaped branching agent, a branched long-chain rare-earth butadiene rubber, a method of preparation, and an application of such agent. The functionalized star-shaped branching agent is a star-shaped butadiene polymer of the structure AY-(Bd)n, where A is an alkyl group with an imino, phenylimino, or epoxy functional group; Y is Si or Sn; Bd is a butadiene polymerization unit; and n is the number of polymer branches, n being a natural number from 3 to 6. The functionalized star-shaped branching agent is used to prepare modified rare-earth butadiene rubber. Branching not only reduces the viscosity of the final phase during polymerization but also introduces functional groups into the molecular chain, increasing the dispersion of reinforcing fillers in the rubber matrix and improving the strength, compressive strength, thermal resistance, and other properties of butadiene rubber. Synthetic butadiene rubber can be used as the sidewall and tread rubber for high-performance tires.

Description

Star-shaped functionalized branching agent, long-chain branched rare earth butadiene rubber, and preparation method and application thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202311164597.9, filed on September 11, 2023, entitled “A star-shaped functionalized branching agent, its preparation and application,” the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of rubber technology, and in particular to a star-shaped functionalized branching agent, a long-chain branched rare earth butadiene rubber, and a preparation method and application thereof. Background Art

[0004] Butadiene rubber (BBR) is widely used in tire, belt, hose, and rubber shoe manufacturing due to its advantages such as high elasticity, low heat buildup, low-temperature resistance, low rolling resistance, flex resistance, wear resistance, and water resistance. Its polymerization process is easy and its raw materials are readily available and inexpensive. Rare earth (neodymium) butadiene rubber (NdBR) has a highly stereoregular molecular chain structure and is susceptible to strain crystallization, resulting in superior tensile / tear resistance, wear resistance, flex resistance, low heat buildup, and low rolling resistance. This reduces tire hysteresis loss and internal heat buildup, lowers rolling resistance, and reduces fuel consumption, while improving tire wear resistance, durability, and high-speed performance. Its overall performance surpasses that of traditional BBRs based on nickel, titanium, and cobalt, meeting the requirements of green tires. However, the more linear structure of rare earth BBR results in a higher viscosity than other BBRs of the same Mooney quality. This higher viscosity complicates production engineering, hinders polymer transport and drying, and also impairs processing performance. Compared with linear rare earth rubber materials, branched rare earth rubber materials, due to their unique physical and chemical properties and branched structure, can obtain high molecular weight polymers while maintaining lower melt and solution viscosities, thus achieving the unity of their physical and mechanical properties and processing performance at lower rubber viscosity.

[0005] From the perspective of molecular structure optimization design, long-chain branched rare earth butadiene rubber can greatly reduce the viscosity of the rubber while maintaining the regularity of the molecular chain and not increasing the molecular chain ends, and at the same time improve the processing performance. It is undoubtedly the most important development direction of butadiene rubber. At the same time, compared with the corresponding linear rare earth butadiene rubber, long-chain branched rare earth butadiene rubber has the following advantages: (1) reducing the viscosity of the rubber during polymerization, reducing the difficulty of engineering in industrial production; (2) improving the cold flow resistance of the raw rubber; (3) increasing tensile strength, reducing hysteresis loss, and reducing heat generation, which is conducive to energy saving and consumption reduction and improving safety, and achieving a comprehensive balance of rolling resistance, anti-slip and wear resistance.

[0006] Carbon black and / or white carbon black are the most widely used reinforcing fillers in rubber. There are no polar groups in the molecular chain of butadiene rubber. During processing, it has poor compatibility with carbon black and / or white carbon black, resulting in a significant Payne effect and a significant decrease in mechanical properties.

[0007] CN1342718A discloses a rare earth-catalyzed diene polymerization method. The addition of a 3D transition metal organic compound (such as nickel neodecanoate) as a regulator during catalyst preparation can adjust the chain transfer rate of the polymerization reaction and control the molecular weight of the polymer, thereby reducing the intrinsic viscosity of the polymer to 5.3 dL / g. However, this results in a reduction in the cis-1,4-structure content in the polyisoprene structural unit to 97.6%.

[0008] CN104140484A discloses a branched rare earth isoprene rubber, a preparation method thereof, and a rubber composition. The preparation method comprises polymerizing isoprene and a branching agent in a first organic solvent in the presence of a rare earth catalyst, wherein the branching agent is liquid polyisoprene. The branching agent used in this method does not contain functional groups and does not promote the mutual dispersion of the rubber and filler.

[0009] CN113461865A discloses a star-branched rare earth rubber and its preparation method. Using a rare earth catalyst system, a two-step process is used to prepare the star-branched rare earth rubber with a rare earth core and branched chains. The rubber produced by this method has a star-shaped structure and does not have long-chain branches. The catalyst used is a cyclopentadienyl rare earth complex as the primary catalyst and contains an organoboron reagent. The catalyst synthesis is complex and relatively expensive.

[0010] In view of the above-mentioned defects, the present invention introduces a star structure and functional groups into the branching agent, which can enhance the polarity of the butadiene rubber molecular chain, improve the compatibility of butadiene rubber with reinforcing fillers, and thus improve the performance of rare earth butadiene rubber products.

[0011] Summary of the Invention

[0012] The inventors of the present invention discovered that the existing rare earth polybutadiene rubber polymer has high viscosity and the polar polybutadiene rubber has poor interaction with carbon black and / or white carbon black, resulting in unsatisfactory performance in terms of tensile strength and compression fatigue temperature rise of rubber products. After research and development, the present invention was developed.

[0013] As a first aspect of the present invention, it relates to a star-functionalized branching agent, wherein the star-functionalized branching agent is a star-functionalized butadiene polymer, and its structure is shown in formula (I).

[0014] AY-(Bd) n Formula (I),

[0015] Wherein, A is an alkyl group with an imine group, a phenylimine group or an epoxy group functional group; Y is Si or Sn; Bd is a butadiene polymerization unit; n is the number of arms of the polymer, and n is a natural number of 3-6.

[0016] According to the present invention, A is a Preferably, A is an alkyl group having no more than 10 carbon atoms and containing the above functional groups.

[0017] According to the present invention, the number average molecular weight of the star-functionalized butadiene polymer is 2000-50000 g / mol, and the molecular weight distribution is 1.2-2.

[0018] As a second aspect of the present invention, a method for preparing the above-mentioned star-shaped functionalized branching agent is provided, comprising: mixing butadiene, a solvent and a structure regulator, carrying out polymerization using alkyl lithium as an initiator, and after the polymerization is completed (the polymerization conversion rate reaches 100%), adding a star-shaped coupling agent to carry out a coupling reaction to obtain the star-shaped functionalized branching agent.

[0019] According to the present invention, the structure regulator can be selected from tetrahydrofuran and / or diethylene glycol dimethyl ether; the alkyl lithium can be n-butyl lithium and / or sec-butyl lithium; and the star coupling agent is an alkoxy silicon or tin compound containing one or more epoxy groups, anilino groups or imino groups.

[0020] According to the present invention, the star-shaped coupling agent is AY-(OCH3)3, wherein A and Y are as defined in the first aspect above. The butadiene active chain segment undergoes a coupling reaction with the alkoxy group in AY-(OCH3)3, and the alkoxy group is removed to obtain a branching agent with a star-shaped functional group (i.e., the star-functionalized branching agent).

[0021] According to the present invention, the structure regulator can increase the vinyl content in the butadiene unit.

[0022] As a third aspect of the present invention, it relates to the use of the above-mentioned star-shaped functionalized branching agent in the preparation of long-chain branched rare earth butadiene rubber.

[0023] As a fourth aspect of the present invention, it relates to a long-chain branched rare earth butadiene rubber, the structural formula of which is shown in formula (II):

[0024] Wherein, Bd1 is a polybutadiene rubber branch chain; m is the number of branches, m is a natural number from 20 to 40; AY-(Bd) n is the main chain, wherein A is an alkyl group with an imine group, a phenylimine group or an epoxy group functional group; Y is Si or Sn; Bd is a butadiene polymerization unit; n is the number of arms of the polymer, and n is a natural number of 3-6.

[0025] According to the present invention, in formula (II), Bd1 is a polybutadiene rubber branched chain having a number average molecular weight of 10,000-20,000 g / mol; AY-(Bd) n It is the main chain and has a number average molecular weight of 2000-50000 g / mol.

[0026] The fifth aspect of the present invention relates to a method for preparing the long-chain branched rare earth cis-1,4-butadiene rubber described in the fourth aspect. The long-chain branched rare earth cis-1,4-butadiene rubber is prepared by coordination polymerization of butadiene in the presence of a branched rare earth catalyst; the branched rare earth catalyst contains the star-functionalized branching agent described in the first aspect.

[0027] According to the present invention, the preparation method of the branched rare earth catalyst comprises: adding neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, the star-shaped functionalized branching agent described in the first aspect, and alkyl aluminum halide to a solvent in sequence, followed by aging.

[0028] According to the present invention, in the preparation method of the rare earth catalyst, the molar ratio of the neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, alkyl aluminum halide, and branching agent is 1: (3-20): (2-20): (1-6): (1-10).

[0029] As a sixth aspect of the present invention, it relates to the use of the long-chain branched rare earth butadiene rubber described in the fourth aspect in the preparation of tires.

[0030] As a seventh aspect of the present invention, it relates to a tire comprising the long-chain branched rare earth butadiene rubber described in the fourth aspect.

[0031] In the present invention, firstly, alkyl lithium is used as an initiator, hydrocarbons are used as solvents, organic matter with a certain polarity is used as a structure regulator, and butadiene is used as a monomer to synthesize a butadiene polymer. Then, a star-shaped coupling agent AY-(OCH3)3 is used for coupling reaction to obtain a star-shaped branching agent, namely AY-(Bd) n , wherein A is an alkyl group with a functional group such as an imino group, a phenylimino group, or an epoxy group; Y is Si or Sn; Bd is a butadiene polymerization unit; n is the number of arms of the polymer, and n is a natural number from 3 to 6. The number average molecular weight of the star-shaped functionalized butadiene polymer is 2000-50000 g / mol, and the molecular weight distribution is 1.2-2. Using this branching agent, butadiene is subjected to coordination polymerization under the action of a branched rare earth catalyst containing the branching agent to prepare a long-chain branched rare earth butadiene rubber. The present invention can not only reduce the viscosity of the polymerized rubber during the polymerization process, but also increase the interaction between the polar butadiene rubber and carbon black and / or white carbon black, thereby ensuring the butadiene rubber has high strength, flex resistance, low heat generation and other properties.

[0032] In the present invention, percentages refer to mass percentages.

[0033] According to the present invention, in some embodiments, the preparation method of the star-shaped functionalized branching agent may include the following steps: the preparation of the branching agent, based on the total mass of the reaction monomer (butadiene) as 100%, first, in a stainless steel reactor with a jacket, argon is replaced 2-4 times, 300-800% of solvent, butadiene monomer and 0.01-0.5% of polar structure regulator are added to the reactor in sequence, and an alkyl lithium initiator (0.1-3.5% by weight, based on the dry basis of alkyl lithium) is added, the reaction temperature is 50-90° C., the reaction pressure is 0.1-0.25 MPa, and the reaction time is 50-80 min; after the conversion rate reaches 100%, a star-shaped coupling agent AY-(OCH3)3 is added to carry out a coupling reaction to form AY-(Bd) n , wherein A is an alkyl group with functional groups such as epoxy, imine, and phenylimine, and n is a natural number of 3-6; the molar ratio of the star coupling agent to the alkyl lithium is (0.1-1):1, the coupling reaction temperature is 60-90°C, the reaction time is 20-80min, and after the reaction is completed, a star-shaped branching agent with functional groups is obtained.

[0034] According to the present invention, in some embodiments, the preparation method of the long-chain branched rare earth butadiene rubber may include the following steps: based on the total mass of the reaction monomers as 100%, first, in a stainless steel reactor with a jacket, argon is replaced 2-4 times, 20-800% of solvent and butadiene monomer are added to the reactor, the branched rare earth catalyst is added to the reactor to initiate a polymerization reaction, the reaction temperature is 50-80°C, the reaction pressure is 0.2-0.4MPa, the reaction time is 120-300min, after the reaction is complete, an alcohol terminator and an antioxidant are added, and the long-chain branched rare earth butadiene rubber product is obtained by condensation and drying.

[0035] According to the present invention, the polymerization reaction used to prepare the star-functionalized branching agent is carried out in an oxygen-free, water-free environment, preferably in an inert atmosphere. The polymerization process is carried out in a hydrocarbon solvent, preferably a hydrocarbon solvent comprising at least one of a linear alkane, a cycloalkane, and an aromatic hydrocarbon, such as hexane, octane, heptane, cyclohexane, benzene, toluene, ethylbenzene, and mixtures thereof, preferably hexane. The amount of hydrocarbon solvent added is not particularly limited and can be the amount typically required for the polymerization reaction, such as 300-800% of the total weight of the monomers.

[0036] According to the present invention, the initiator used to prepare the star-shaped functionalized branching agent is preferably an organic monolithium compound, and a commonly used hydrocarbon monolithium compound is RLi, wherein R can be selected from at least one of a saturated aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group containing 1 to 20 carbon atoms. The organic monolithium compound may include n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthalenelithium, cyclohexyllithium, dodecyllithium, etc. The most commonly used are n-butyllithium and / or sec-butyllithium. The amount of organic lithium added is determined by the molecular weight of the target polymer.

[0037] According to the present invention, the polymerization system used to prepare the star-shaped functionalized branching agent is added with 0.01-0.5% of a polar organic compound as a structure modifier. This polarizes or solvates the alkyl lithium initiator, reduces its degree of association, and increases the initiation reaction rate of the initiator (e.g., n-butyl lithium). Simultaneously, the structure modifier can increase the vinyl content in the butadiene unit. Examples of such polar organic compounds include diethylene glycol dimethyl ether (2G), tetrahydrofuran (THF), ethyl ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether (DME), triethylamine, and hexamethylphosphonic triamide, with diethylene glycol dimethyl ether and / or tetrahydrofuran being preferred.

[0038] According to the present invention, the star-shaped coupling agent used in the preparation of the star-shaped functionalized branching agent is an alkoxy silicon compound containing one or more epoxy groups, phenylimine groups or imine groups, or an alkoxy tin compound containing one or more epoxy groups, phenylimine groups or imine groups, and its general formula is: AY-(OR2)3, wherein A is an alkyl group containing a functional group such as an epoxy group, a phenylimine group or an imine group, and the functional group can be Preferably, A is an alkyl group containing the aforementioned functional groups and having no more than 10 carbon atoms; R2 is an alkyl group containing 1-4 carbon atoms; and Y is Si or Sn. The coupling agent is a silicon compound or tin compound containing multiple active centers. The coupling agent containing the aforementioned functional groups reacts with the "active ends" of the polymer to introduce functional groups such as epoxy, imine, and phenylimine into the polymer, thereby producing a functional group-containing polymer. In the present invention, the amount of the multi-active center coupling agent used depends on the amount of initiator. Generally, the molar ratio of coupling agent to organolithium (initiator) is (0.1-1):1.

[0039] According to the present invention, the method for preparing the branched rare earth catalyst can include: adding a rare earth element-containing carboxylate, an alkyl aluminum, an alkyl aluminum hydride, the star-shaped functionalized branching agent, and a halogen compound to a solvent, mixing uniformly, and then aging at room temperature for 0.2-2 hours to obtain the branched rare earth catalyst. The molar ratio of the star-shaped functionalized branching agent to the rare earth element-containing carboxylate can be (1-10):1.

[0040] In the present invention, during the polymerization of the long-chain branched rare earth butadiene rubber, the amount of the branched rare earth catalyst added is measured by the molar ratio of the carboxylate containing the rare earth element to the butadiene monomer, and the molar ratio of the carboxylate containing the rare earth element to the butadiene monomer is (2×10 -5 -2×10 -4 ):1.

[0041] According to the present invention, during the preparation process of the branched rare earth catalyst, the branching agent is aged together with the catalytic rare earth element-containing neodymium carboxylate, alkyl aluminum, etc. This can change the phase state of the catalyst and increase the degree of branching, compared to the reaction mode of first adding the rare earth catalyst (i.e., the rare earth element-containing carboxylate) to the polymerization system to polymerize into a macromolecule and then adding the branching agent to the system. On the one hand, the branching agent can serve as a large sterically hindered ligand. The large volume of steric hindrance destroys the association of the rare earth neodymium, avoiding the formation of heterogeneous particle precipitation (i.e., heterogeneous catalyst). In industrial production, heterogeneous catalysts are prone to clogging pipelines due to precipitation, causing polymerization instability and affecting long-term production. On the other hand, it can avoid the introduction of trace impurities when the branching agent is added in the late stage of polymerization. The introduction of impurities will reduce the branching coefficient and affect the branching effect.

[0042] According to the present invention, a polymer can be synthesized by using the preparation method of the long-chain branched rare earth butadiene rubber provided by the present invention. In the polymer, the cis-1,4-structure content is greater than 98%, the weight-average molecular weight is adjustable within the range of 200,000 to 1,000,000, the branching coefficient of the polymer is 2.0-3.5, and the viscosity (η) of the toluene solution of the polymer at a concentration of 5% by weight at 25°C is 1.2-3dL / g.

[0043] The present invention adopts the star-shaped functionalized branching agent to prepare modified rare earth butadiene rubber. The star-shaped branching can significantly reduce the viscosity of the polymer glue solution, bringing convenience to processes such as heat transfer, transportation, glue spraying and coagulation in production. At the same time, the functional group can increase the polarity of the rubber, improve the compatibility of non-polar rubber with carbon black and / or white carbon black, and bring good processing performance and excellent tensile strength, flexural resistance, low heat generation and other properties. DETAILED DESCRIPTION

[0044] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0045] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0046] The branching coefficient is calculated using the formula g = ML 1+4 100℃ * Calculated by 10 / SV, where g is the branching coefficient (unit: dimensionless), ML 1+4 100℃ is the Mooney viscosity (MU) of the colloid sample, and SV is the dynamic viscosity of the colloid sample (unit: mPa·s). The viscosity of a 5% toluene solution was measured using a coaxial cylinder viscometer.

[0047] The viscosity of the polymer glue was measured using an Ubbelohde viscometer at 25°C with toluene as the solvent. The calculation formula is [η] = [2(η sp -lnη r )] 1 / 2 / c, where η r =t / t0,η sp =η r -1, t is the flow time (unit: second) of the toluene solution of the polymer with a concentration of c (unit: weight %), and t0 is the flow time (unit: second) of toluene.

[0048] The tensile strength is determined using the method specified in GB / T 528-2009.

[0049] The compression fatigue temperature rise is determined using the method specified in GB / T1687-2016.

[0050] The present invention will be described in detail below through examples. In the following examples and comparative examples, unless otherwise specified, conventional methods are used; the reagents and materials described are all commercially available unless otherwise specified.

[0051] The physical properties and dynamic mechanical properties of the polybutadiene rubber prepared in the following examples and comparative examples are shown in Table 1.

[0052] Example 1

[0053] (1) Preparation of star-shaped functionalized branching agent: In a 1L jacketed reactor, argon was introduced to replace the system three times. 240 g of hexane, 0.2 g of tetrahydrofuran, 60 g of butadiene, and 30 mmol of n-butyl lithium were added to the reactor. The temperature was raised to 60°C for reaction. The reaction pressure was 0.15 MPa. The polymerization was carried out for 50 min. After the monomers were completely converted, 10 mmol of The coupling agent is subjected to coupling reaction at a temperature of 60° C. and a reaction time of 80 min. After the coupling reaction is completed, the reaction is terminated and set aside for use.

[0054] The prepared star-shaped functionalized branching agent is a polymer represented by the above formula (I), wherein A is Y is Si, Bd is a butadiene polymerization unit, n=3, the number average molecular weight of the polymer (star-shaped functionalized branching agent) is 2000 g / mol, and the molecular weight distribution is 2.0.

[0055] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 50 mL of hexane was added to a dry catalyst preparation bottle, and then 0.03 mmol of neodymium isooctanoate, 0.75 mmol of triisobutylaluminum, 0.15 mmol of diethylaluminum hydride, 0.09 mmol of diethylaluminum chloride, and 0.2 mmol of the star-shaped functionalized branching agent prepared in step (1) were mixed in the order of hexane, neodymium isooctanoate, triisobutylaluminum, diethylaluminum hydride, star-shaped functionalized branching agent, and diethylaluminum chloride, and then aged at room temperature for 1 hour to obtain a branched rare earth catalyst for standby use.

[0056] Under argon protection, 3200 g of hexane and 800 g of butadiene were added to a 10 L stainless steel reactor with a jacket, and then the branched rare earth catalyst prepared above was added according to the molar ratio of butadiene to neodymium isooctanoate, wherein the molar ratio of neodymium isooctanoate to butadiene was 1×10 -4 The reaction was then polymerized at 60-70°C and 0.2 MPa for 3 hours, followed by the addition of an ethanol solution of 2,6-di-tert-butyl-p-methylphenol at a concentration of 1 wt% of the polymer product. The rubber solution was wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)m represents a polybutadiene rubber branch chain having a number average molecular weight of 10,000 g / mol and a number of branches, m, of 20. is the main chain, the number average molecular weight of the main chain is 2000 g / mol, and Bd is a butadiene polymerization unit.

[0057] Comparative Example 1

[0058] The method of Example 1 was followed, except that no star-shaped functionalized branching agent was added during the polymerization process. The other step conditions and raw material addition amounts were the same as those of Example 1, to obtain a universal rare earth butadiene rubber product.

[0059] Example 2

[0060] (1) Preparation of star-shaped functionalized branching agent: In a 1L jacketed reactor, argon was introduced to replace the system three times. 420 g of hexane, 0.02 g of pentamethyldiethylenetriamine, 60 g of butadiene, and 15 mmol of n-butyllithium were added to the reactor. The temperature was raised to 70°C for reaction. The reaction pressure was 0.2 MPa and the polymerization was carried out for 60 min. After the monomers were completely converted, 5 mmol of n-butyllithium was added at a time. The coupling agent was used for coupling reaction at a temperature of 70° C. and a reaction time of 70 min. After the coupling reaction was completed, the reaction was terminated and set aside for use.

[0061] The prepared star-shaped functionalized branching agent is a polymer represented by the above formula (I), wherein A is Y is Si, Bd is a butadiene polymerization unit, n=3, the number average molecular weight of the polymer (star-shaped functionalized branching agent) is 4000 g / mol, and the molecular weight distribution is 1.8.

[0062] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 50 mL of hexane was added to a dry catalyst preparation bottle, and then 0.04 mmol of neodymium nonanoate, 0.6 mmol of triisobutylaluminum, 0.4 mmol of dibutylaluminum hydride, 0.16 mmol of diisobutylaluminum chloride, and 0.3 mmol of the star-shaped functionalized branching agent prepared in step (1) were added. The mixture was mixed in the order of hexane, neodymium nonanoate, triisobutylaluminum, dibutylaluminum hydride, star-shaped functionalized branching agent, and diisobutylaluminum chloride, and then aged at 50°C for 30 min to obtain a branched rare earth catalyst for standby use.

[0063] Under argon protection, 4000 g of hexane and 800 g of butadiene were added to a 10 L stainless steel reactor with a jacket, and then the branched rare earth catalyst prepared above was added, wherein the molar ratio of neodymium nonanoate to butadiene was 5×10 -5 The reaction was terminated by polymerization at 60°C and 0.3 MPa for 4 hours, followed by the addition of an ethanol solution of antioxidant 1076 (octadecyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate) at 1 wt% of the total mass of the polymer product. The rubber solution was wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)m represents a polybutadiene rubber branch chain with a number average molecular weight of 14,000 g / mol and a number of branches, m, of 25. is the main chain, the number average molecular weight of the main chain is 4000 g / mol, and Bd is a butadiene polymerization unit.

[0064] Comparative Example 2

[0065] The method of Example 2 was followed, except that a non-functionalized butadiene polymer was used as the branching agent, i.e., no star coupling agent was added in the branching agent preparation step. The other step conditions and raw material addition amounts were the same as in Example 2, to obtain a linear butadiene polymer.

[0066] Example 3

[0067] (1) Preparation of star-shaped functionalized branching agent: In a 1L jacketed reactor, argon was introduced to replace the system three times. 560 g of cyclohexane, 0.15 g of diethylene glycol dimethyl ether, 70 g of butadiene, and 7 mmol of n-butyl lithium were added to the reactor. The temperature was raised to 80°C for reaction. The reaction pressure was 0.25 MPa and the polymerization was carried out for 50 min. After the monomers were completely converted, 2.33 mmol of n-butyl lithium was added at once. The coupling agent is used for coupling reaction at a temperature of 80° C. and a reaction time of 30 min. After the coupling reaction is completed, the reaction is terminated and set aside for use.

[0068] The prepared star-shaped functionalized branching agent is a polymer represented by the above formula (I), wherein A is Y is Sn, Bd is a butadiene polymerization unit, n=3, the number average molecular weight of the polymer (star-shaped functionalized branching agent) is 10,000 g / mol, and the molecular weight distribution is 1.8.

[0069] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 95 mL of hexane was added to a dry catalyst preparation bottle, followed by the addition of 0.02 mmol of neodymium neodecanoate, 0.8 mmol of diisobutylaluminum hydride, 0.04 mmol of sesquiethylaluminum chloride, and 0.18 mmol of the star-shaped functionalized branching agent prepared in step (1). The mixture was mixed in the order of hexane, neodymium neodecanoate, diisobutylaluminum hydride, star-shaped functionalized branching agent, and sesquiethylaluminum chloride, and then aged at room temperature for 1 h to obtain a branched rare earth catalyst for later use.

[0070] Under argon protection, 3600 g of cyclohexane and 600 g of butadiene were added to a 10 L stainless steel reactor with a jacket, and then the branched rare earth catalyst prepared above was added, wherein the molar ratio of neodymium neodecanoate to butadiene was 2×10 -5 The reaction was terminated by polymerization at 70°C and 0.35 MPa for 3 hours, followed by the addition of an ethanol solution of antioxidant 1076 (octadecyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate) at 1 wt% of the total mass of the polymer product. The rubber solution was wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)m represents a polybutadiene rubber branch chain having a number average molecular weight of 16,000 g / mol and a number of branches m of 30. is the main chain, the number average molecular weight of the main chain is 10000 g / mol, and Bd is a butadiene polymerization unit.

[0071] Comparative Example 3

[0072] The method of Example 3 was followed, except that: the branching agent was epoxidized liquid polybutadiene rubber (NISSO PB-JP JP200, Japan Soda), wherein the molar ratio of the epoxidized functional group to the double bond was 20%-40%, and the other step conditions and raw material addition amounts were the same as in Example 3 to obtain a butadiene polymer.

[0073] Example 4

[0074] (1) Preparation of star-shaped functionalized branching agent: In a 1L jacketed reactor, argon was introduced to replace the system three times. 280g of cyclopentane, 0.09g of tetrahydrofurfuryl ether, 70g of butadiene were added to the reactor, and 8mmol of n-butyl lithium was accurately added. The temperature was raised to 80°C for reaction. The reaction pressure was 0.25MPa and the polymerization was carried out for 50min. After the monomers were completely converted, 1.6mmol of The coupling agent is used for coupling reaction at a temperature of 90° C. and a reaction time of 20 min. After the coupling reaction is completed, the reaction is terminated and set aside for use.

[0075] The prepared star-shaped functionalized branching agent is a polymer represented by the above formula (I), wherein A is Y is Si, Bd is a butadiene polymerization unit, n=6, the number average molecular weight of the polymer (star-shaped functionalized branching agent) is 20,000 g / mol, and the molecular weight distribution is 1.5.

[0076] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 50 mL of hexane was added to a dry catalyst preparation bottle, followed by the addition of 0.05 mmol of neodymium decanoate, 0.25 mmol of tributylaluminum, 1.5 mmol of diethylaluminum hydride, 0.15 mmol of dibutylaluminum chloride, and 0.4 mmol of the star-shaped functionalized branching agent prepared in step (1). The mixture was mixed in the order of hexane, neodymium decanoate, tributylaluminum, diethylaluminum hydride, star-shaped functionalized branching agent, and dibutylaluminum chloride, and then aged at room temperature for 1 h to obtain a branched rare earth catalyst for later use.

[0077] Under argon protection, 4000 g of cyclopentane and 800 g of butadiene were added to a 10 L stainless steel reactor with a jacket, and then the branched rare earth catalyst prepared above was added, wherein the molar ratio of neodymium decanoate to butadiene was 2×10 -4 The reaction was terminated by polymerization at 90°C and 0.4 MPa for 2 hours, followed by the addition of an ethanol solution of 2,6-di-tert-butyl-p-methylphenol (1 wt% of the total mass of the polymer product). The rubber solution was wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)m represents a polybutadiene rubber branch chain with a number average molecular weight of 20,000 g / mol and a number of branches, m, of 35. is the main chain, the number average molecular weight of the main chain is 20000 g / mol, and Bd is a butadiene polymerization unit.

[0078] Comparative Example 4

[0079] The method of Example 4 was followed, except that the branching agent was not aged together with the catalyst (neodymium decanoate), but was added after the polymerization was completed. The branching agent was the branching agent prepared in step (1) of Example 4. The other step conditions and the amounts of raw materials added were the same as those in Example 4, to obtain a butadiene polymer.

[0080] Example 5

[0081] (1) Preparation of star-shaped functionalized branching agent: In a 1L jacketed reactor, argon was introduced to replace the system three times. 480 g of hexane, 0.35 g of tetrahydrofuran, 80 g of butadiene, and 2.3 mmol of n-butyl lithium were added to the reactor. The temperature was raised to 90°C for reaction. The reaction pressure was 0.25 MPa and the polymerization was carried out for 50 min. After the monomers were completely converted, 0.8 mmol of n-butyl lithium was added at a time. The coupling agent is used for coupling reaction at a temperature of 80° C. and a reaction time of 30 min. After the coupling reaction is completed, the reaction is terminated and set aside for use.

[0082] The prepared star-shaped functionalized branching agent is a polymer represented by the above formula (I), wherein A is Y is Sn, Bd is a butadiene polymerization unit, n=3, the number average molecular weight of the polymer (star-shaped functionalized branching agent) is 35,000 g / mol, and the molecular weight distribution is 1.4.

[0083] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 70 mL of cyclohexane was added to a dry catalyst preparation bottle, followed by the addition of 0.01 mmol of neodymium isooctanoate, 0.05 mmol of triethylaluminum, 0.05 mmol of dibutylaluminum hydride, 0.04 mmol of diisobutylaluminum chloride, and 0.08 mmol of the star-shaped functionalized branching agent prepared in step (1). The mixture was mixed in the order of cyclohexane, neodymium isooctanoate, dibutylaluminum hydride, star-shaped functionalized branching agent, and diisobutylaluminum chloride, and then aged at room temperature for 0.5 h to obtain a branched rare earth catalyst for later use.

[0084] Under argon protection, 3200 g of hexane and 800 g of butadiene were added to a 10 L stainless steel reactor with a jacket, and then the branched rare earth catalyst prepared above was added, wherein the molar ratio of neodymium isooctanoate to butadiene was 1×10 -4The reaction was terminated by polymerization at 80°C and 0.35 MPa for 3 hours, followed by the addition of an ethanol solution of 2,6-di-tert-butyl-p-methylphenol (1 wt% of the total mass of the polymer product). The rubber solution was wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)m represents a polybutadiene rubber branch chain with a number average molecular weight of 15,000 g / mol and a number of branches, m, of 40. is the main chain, the number average molecular weight of the main chain is 35000 g / mol, and Bd is a butadiene polymerization unit.

[0085] Comparative Example 5

[0086] The method of Example 5 was followed, except that the branching agent was not aged together with the catalyst (neodymium isooctanoate), but was added after the polymerization was completed. The branching agent was the dialkyldiolefinsilane (i.e., dimethyldipentadienylsilane) used in Example 4 of CN113461865A. The other step conditions and raw material addition amounts were the same as in Example 5 to obtain a butadiene polymer.

[0087] Example 6

[0088] (1) Preparation of star-shaped functionalized branching agent: In a 1L jacketed reactor, argon was introduced to replace the system three times. 420 g of cyclohexane, 0.24 g of tetrahydrofuran, and 70 g of butadiene were added to the reactor, and 1.4 mmol of n-butyl lithium was accurately added. The temperature was raised to 80°C for reaction, the reaction pressure was 0.25 MPa, and the polymerization was carried out for 50 min. After the monomers were completely converted, 0.56 mmol of n-butyl lithium was added at once. The coupling agent was used for coupling reaction at a temperature of 60° C. and a reaction time of 70 min. After the coupling reaction was completed, the reaction was terminated and set aside for use.

[0089] The prepared star-shaped functionalized branching agent is a polymer represented by the above formula (I), wherein A is Y is Si, Bd is a butadiene polymerization unit, n=3, the polymer molecular weight is 50,000 g / mol, and the molecular weight distribution is 1.2.

[0090] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 80 mL of hexane was added to a dry catalyst preparation bottle, followed by 0.04 mmol of neodymium decanoate, 0.20 mmol of tributylaluminum, 1.0 mmol of diethylaluminum hydride, 0.12 mmol of dibutylaluminum chloride, and 0.28 mmol of the star-shaped functionalized branching agent prepared in step (1). The mixture was mixed in the order of hexane, neodymium decanoate, tributylaluminum, diethylaluminum hydride, star-shaped functionalized branching agent, and dibutylaluminum chloride, and then aged at room temperature for 0.6 h to obtain a branched rare earth catalyst for later use.

[0091] Under argon protection, 3000 g of cyclohexane and 800 g of butadiene were added to a 10 L stainless steel reactor with a jacket, and then the branched rare earth catalyst prepared above was added, wherein the molar ratio of neodymium decanoate to butadiene was 5 × 10 -4 The reaction was then polymerized at 70°C and 0.3 MPa for 3.5 hours. An ethanol solution of the antioxidant TNPP was added at a concentration of 1 wt% of the total mass of the polymer product to terminate the reaction. The rubber solution was wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)m represents a polybutadiene rubber branch chain with a number average molecular weight of 18,000 g / mol and a number of branches, m, of 30. is the main chain, the number average molecular weight of the main chain is 50000 g / mol, and Bd is a butadiene polymerization unit.

[0092] Comparative Example 6

[0093] The method of Example 6 was followed, except that the branching agent was not aged with the catalyst (neodymium decanoate), but was added after the polymerization was completed. The branching agent was the liquid isoprene rubber (i.e., liquid polyisoprene) used in Example 1 of CN104140484A. The other step conditions and raw material addition amounts were the same as in Example 6 to obtain a butadiene polymer.

[0094] Table 1

[0095] The results in Table 1 indicate that the cis-1,4 structure content of the long-chain branched rare earth butadiene rubber synthesized in the present invention is above 98%, the branching coefficient is between 2.48 and 3.12 (a high branching coefficient indicates good branching effect), and the rubber viscosity is significantly lower than that of the comparative example. Because the branches also carry functional groups, the tensile strength and compression fatigue temperature rise (which can represent heat generation, the lower the better) are significantly better than those of the comparative example. As can be seen from Example 1 and Comparative Example 1, the branching reduces the rubber viscosity from 5.67 dL / g to 2.35 dL / g, which is beneficial for solving the transportation and post-processing problems during the polymerization process. At the same time, the tensile strength increases from 16.5 MPa to 18.6 MPa, and the compression fatigue temperature rise decreases from 27.6°C to 23.2°C, indicating low fatigue heat generation in the material. As can be seen from Examples 2-3 and Comparative Example 2-3, the branched amino functional groups promote the dispersion of carbon black and / or white carbon black in the rubber, thereby increasing tensile strength and significantly reducing the compression fatigue temperature rise. This increase in tensile strength is highly beneficial for improving the stiffness and reducing heat buildup of tire sidewall materials. As can be seen from Examples 4-6 and Comparative Example 4-6, Example 4-6, in which the branching agent and catalyst (i.e., a carboxylate containing a rare earth element) are co-aged and then added to the polymerization system, exhibits a higher branching coefficient, lower rubber viscosity, and better rolling resistance compared to Comparative Example 4-6, in which the branching agent is added to the system late in the polymerization process.

[0096] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A star-shaped functionalized branching agent, characterized in that: The star-functionalized branching agent is a star-functionalized butadiene polymer, as shown in formula (I), AY-(Bd) n Formula (I), Wherein, A is an alkyl group with an imine group, a phenylimine group or an epoxy functional group; Y is Si or Sn; Bd is a butadiene polymerization unit; n is the number of arms of the polymer, and n is a natural number of 3-6.

2. The star-shaped functionalized branching agent according to claim 1, characterized in that A is with The alkyl group; And / or, the number average molecular weight of the star-shaped functionalized polymer is 2000-50000 g / mol, and the molecular weight distribution is 1.2-2.

3. A method for preparing the star-shaped functionalized branching agent according to claim 1 or 2, characterized in that: The method comprises: mixing butadiene, a solvent and a structure regulator, taking alkyl lithium as an initiator, performing polymerization, and after the polymerization is completed, adding a star-shaped coupling agent to perform a coupling reaction to obtain a star-shaped functionalized branching agent.

4. The method according to claim 3, characterized in that The structure regulator is tetrahydrofuran and / or diethylene glycol dimethyl ether; And / or, the alkyl lithium is n-butyl lithium and / or sec-butyl lithium; And / or, the star coupling agent is an alkoxy silicon compound containing one or more epoxy groups, phenylimine groups or imine groups, or an alkoxy tin compound containing one or more epoxy groups, phenylimine groups or imine groups.

5. The method according to claim 4, characterized in that The star coupling agent is AY-(OR2)3, wherein A is an alkyl group with an imine group, a phenylimine group or an epoxy group functional group; Y is Si or Sn; and R2 is an alkyl group containing 1 to 4 carbon atoms.

6. The method according to claim 5, characterized in that A is with of alkyl.

7. The method according to claim 3, characterized in that Based on 100% by weight of butadiene, the weight of the solvent is 300-800%, the weight of the structure regulator is 0.01-0.5%, and the weight of the alkyl lithium is 0.1-3.5%; And / or, the molar ratio of the star coupling agent:alkyl lithium is (0.1-1):

1.

8. The method according to claim 3, characterized in that The polymerization conditions include: temperature of 50-90°C, pressure of 0.1-0.25MPa, and time of 50-80min; And / or, the coupling reaction conditions include: temperature of 60-90° C., reaction time of 20-80 min.

9. Use of the star-shaped functionalized branching agent according to claim 1 or 2 in the preparation of long-chain branched rare earth butadiene rubber.

10. A long-chain branched rare earth butadiene rubber, characterized in that: The long-chain branched rare earth butadiene rubber is as shown in formula (II), Wherein, Bd1 is a polybutadiene rubber branch chain; m is the number of branches, m is a natural number of 20-40; AY-(Bd) n is the main chain, wherein A is an alkyl group with an imine group, a phenylimine group or an epoxy group functional group; Y is Si or Sn; Bd is a butadiene polymerization unit; n is the number of arms of the polymer, and n is a natural number of 3-6.

11. The long-chain branched rare earth butadiene rubber according to claim 10, characterized in that: Bd1 is a polybutadiene rubber branched chain with a number average molecular weight of 10000-20000 g / mol; AY-(Bd) n It is the main chain and has a number average molecular weight of 2000-50000 g / mol.

12. A method for preparing the long-chain branched rare earth butadiene rubber according to claim 10 or 11, characterized in that: The method comprises: preparing long-chain branched rare earth cis-1,1-butadiene rubber by coordination polymerization under the action of a branched rare earth catalyst; wherein the branched rare earth catalyst contains the star-shaped functionalized branching agent according to claim 1 or 2.

13. The method according to claim 12, characterized in that The conditions of the coordination polymerization include: temperature of 50-80° C., pressure of 0.2-0.4 MPa, and time of 120-300 min.

14. The method according to claim 12 or 13, characterized in that The preparation method of the branched rare earth catalyst comprises: adding neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, the star-shaped functionalized branching agent according to claim 1 or 2, and alkyl aluminum halide to a solvent in sequence, and then aging.

15. The method according to claim 14, characterized in that The molar ratio of the neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, alkyl aluminum halide, and star-shaped functionalized branching agent is 1:(3-20):(2-20):(1-6):(1-10).

16. Use of the long-chain branched rare earth butadiene rubber according to claim 10 or 11 in the preparation of tires.

17. A tire, characterized in that: The tire comprises the long-chain branched rare earth butadiene rubber according to claim 10 or 11.