Functionalized rubber branching agent and preparation and application thereof

Abstract

The invention discloses a functionalized rubber branching agent, the branching agent is a functionalized butadiene / styrene copolymer, the structure of the branching agent is # imgabs0 #, and Bd is a polymerized butadiene unit; # imgabs 1 # is an amine-containing N, N-dialkylamino styrene compound, the content of the amine-containing N, N-dialkylamino styrene compound in the branching agent copolymer is 1-15%, and R1 and R2 are respectively and independently selected from alkyl with 1-4 carbon atoms. The invention also discloses a preparation method and application thereof. When the rubber branching agent is used for modifying rare earth butadiene rubber, the viscosity of a rubber solution in the polymerization process can be reduced, more functional groups can be introduced into a molecular chain, and the functional groups can enhance the dispersion of reinforcing filler, especially white carbon black, in a rubber matrix and improve the strength, flexing resistance and other properties of the butadiene rubber; the synthesized butadiene rubber is suitable for being used as a high-performance tire sidewall and tread combined rubber.

Description

Technical Field

[0001] The invention relates to a functionalized rubber branching agent and its preparation and application. Background Art

[0002] The tire industry has increasingly higher requirements for rubber raw materials. In addition to requiring low rolling resistance and good wear resistance, it also requires increasing tire load while reducing tire weight. Butadiene rubber is widely used in high-performance tires because of its advantages such as high elasticity, low heat generation, low temperature resistance, low rolling resistance, flex resistance, wear resistance, and water resistance. The polymerization process is easy to operate, and the raw materials are cheap and easy to obtain. The rare earth (neodymium) butadiene rubber (NdBR) molecular chain has a highly stereoregular structure and is prone to strain crystallization, thus giving it more excellent tensile / tear resistance, wear resistance, flex resistance, low heat generation, low rolling resistance, etc., which can reduce tire hysteresis loss and internal heat generation, reduce rolling resistance, reduce fuel consumption, and improve tire wear resistance, durability and high-speed performance. Its comprehensive performance is better than traditional butadiene rubber such as nickel, titanium and cobalt, meeting the needs of green tires. On the other hand, the higher linear structure of rare earth butadiene rubber makes its solution viscosity higher than that of other types of butadiene rubber with the same Mooney. The high viscosity of the rubber increases the difficulty of engineering production, makes it difficult to transport and dry the polymer, and also makes the processing performance worse. Compared with linear rare earth rubber materials, branched rare earth rubber materials have the unique physical and chemical properties and branched structure, and can obtain high molecular weight polymers while maintaining low melt and solution viscosity, that is, to achieve the unity of its physical and mechanical properties and processing performance at a lower viscosity of the rubber.

[0003] 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, which 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 the polymerization process and reducing the difficulty of engineering in industrial production; (2) improving the cold flow resistance of the raw rubber; (3) improving the tensile strength, reducing the hysteresis loss, and reducing the 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. Summary of the invention

[0004] The inventors found that the existing rare earth butadiene rubber polymer has a high viscosity and poor interaction with silica, resulting in the strength and flexural resistance of the rubber product failing to meet expectations. After further research and development, the present invention was made.

[0005] As one aspect of the present invention, it relates to a functionalized rubber branching agent, wherein the branching agent is a functionalized butadiene / styrene copolymer, and its structure is shown in formula (I):

[0006]

[0007] Wherein, Bd is a butadiene polymerization unit; The N,N-dialkylamino styrene compound containing amine has a content of 1-15% in the branching agent, st is styrene, R1 and R2 are independently selected from alkyl groups of 1-4 carbon atoms, and can be the same or different. In a specific embodiment, the number average molecular weight of the copolymer is 2000-30000, and the molecular weight distribution is 1.2-2.0.

[0008] As another aspect of the present invention, it relates to a method for preparing the above-mentioned rubber branching agent, comprising: mixing butadiene, a styrene derivative monomer (such as N,N-diethylaminostyrene) and a structure regulator (such as tetrahydrofuran, diethylene glycol dimethyl ether, etc.), using alkyl lithium (such as n-butyl lithium) as an initiator, and polymerizing. The structure regulator can increase the content of vinyl in the butadiene unit.

[0009] As another aspect of the present invention, it relates to the use of the above functionalized rubber branching agent in the preparation of long-chain branched rare earth butadiene rubber.

[0010] As another aspect of the present invention, it relates to a long-chain branched rare earth butadiene rubber, the structure of which is shown in formula (II):

[0011]

[0012] Wherein, Bd1 is a polybutadiene rubber branch chain (in a specific embodiment, the number average molecular weight is 10000-20000); m is the number of branches, which is a natural number selected from 20-40; is the main chain (in a specific embodiment, the number average molecular weight is 2000-30000), wherein Bd is a butadiene polymerization unit, The invention is an N,N-dialkylamino styrene compound containing amine, the content of which in the main chain copolymer is 1-15%, and R1 and R2 are each independently selected from an alkyl group with 1-4 carbon atoms.

[0013] As another aspect of the present invention, it relates to a method for preparing the above-mentioned long-chain branched rare earth butadiene rubber, comprising: preparing the long-chain branched rare earth butadiene rubber by coordination polymerization under the action of a branched rare earth catalyst, wherein the branched rare earth catalyst contains the above-mentioned rubber branching agent. The branched rare earth catalyst is prepared by sequentially adding neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, the above-mentioned functionalized rubber branching agent, and alkyl aluminum halide to a solvent, aging, and then preparing the same. The molar ratio of the rare earth neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, alkyl aluminum halide, and branching agent is 1:3-20:2-20:1-6:1-10.

[0014] As another aspect of the present invention, it relates to the use of the long-chain branched rare earth butadiene rubber in the preparation of tires.

[0015] As another aspect of the present invention, it relates to a tire, comprising the long-chain branched rare earth butadiene rubber.

[0016] In the present invention, alkyl lithium is used as an initiator, hydrocarbons are used as solvents, organic matter with a certain polarity is used as a structural regulator, and the reaction monomers are composed of butadiene and styrene derivatives to synthesize a branching agent with a functional group in the chain. Bd is a butadiene polymerization unit, It is an N,N-dialkylamino styrene compound containing amine, and its mass content in the branching agent is 1-15%, and styrene and butadiene are random copolymers. The branching agent and butadiene are used under the action of rare earth catalysts to prepare long-chain branched rare earth cis-butadiene rubber through coordination polymerization. The invention not only reduces the viscosity of the polymerized rubber during the polymerization process, but also increases the interaction between the polar butadiene rubber and the carbon black / white carbon black, thereby ensuring the butadiene rubber has the properties of high strength, flex resistance, low heat generation and the like.

[0017] The percentages described in the present invention all refer to mass percentages.

[0018] In a specific embodiment, the preparation method of the rubber branching agent may include the following steps: adding a solvent, butadiene, a styrene derivative monomer, a structure regulator, and an initiator to a reactor in sequence, based on 100% of the total mass of the reaction monomers, the reaction temperature is 50°C to 90°C, the reaction pressure is 0.1MPa to 0.25MPa, and the reaction time is 50min to 80min; after no free monomers are present in the polymerization reaction, a branching agent with functional groups is obtained.

[0019] In a specific embodiment, the preparation method of the long-chain branched butadiene rubber may include the following steps: adding 200% to 800% of solvent and butadiene monomer to a reactor based on 100% of the total mass of the reaction monomers, adding an aged branched rare earth catalyst to the reactor to initiate a polymerization reaction, the reaction temperature is 50°C to 80°C, the reaction pressure is 0.2MPa to 0.4MPa, the reaction time is 120min to 300min, and 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.

[0020] The polymerization reaction for preparing the branching agent of the present invention is carried out in an oxygen-free, water-free, preferably in an inert gas environment. The polymerization process is completed in a hydrocarbon solvent, and the preferred hydrocarbon solvents include straight-chain alkanes, cycloalkanes, such as hexane, octane, heptane, cyclohexane and mixtures thereof, preferably hexane. The amount added is not particularly limited, and the amount required for the usual polymerization reaction can be used, such as 300 to 800 wt% of the total weight of the monomers.

[0021] The styrene derivative monomer for preparing the branching agent of the present invention is N,N-dialkylaminostyrene containing amine, such as N,N-dimethylaminostyrene, N,N-diethylaminostyrene, N,N-di-tert-butylaminostyrene and the like.

[0022] The initiator used in the preparation of the branching agent of the present invention is preferably an organic monolithium compound, and a hydrocarbon monolithium compound, i.e., RLi, is commonly used, wherein R is a saturated aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group or a composite group of the above groups containing 1 to 20 carbon atoms. Such organic lithium compounds include n-butyl lithium, sec-butyl lithium, methyl butyl lithium, phenyl butyl lithium, naphthalene lithium, cyclohexyl lithium, dodecyl lithium, etc. The most commonly used are n-butyl lithium and sec-butyl lithium. The amount of organic lithium added is determined by the molecular weight of the designed polymer.

[0023] In the polymerization system for preparing the branching agent of the present invention, 0.01% to 0.5% of a polar organic compound can be added as a structural regulator to cause the alkyl lithium initiator to produce a polarization or solvation effect, reduce its degree of association, increase the initiation reaction speed of a positive initiator such as n-butyl lithium, and simultaneously change the polymerization reactivity ratio of butadiene and styrene derivatives to make the two randomly copolymerize. The structural regulator can also increase the content of vinyl in the butadiene unit. Such polar organic compounds include diethylene glycol dimethyl ether (2G), tetrahydrofuran (THF), ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether (DME), triethylamine, hexamethylphosphonic triamide, etc., preferably diethylene glycol dimethyl ether and tetrahydrofuran.

[0024] The rare earth carboxylate is one of neodymium octanoate, neodymium isooctanoate, neodymium nonanoate, neodymium decanoate or neodymium neodecanoate; the alkyl aluminum is one of trimethyl aluminum, triethyl aluminum, tripropyl aluminum, tributyl aluminum, triisobutyl aluminum and tripentylaluminum; the alkyl aluminum hydride is one of diethyl aluminum hydride, dibutyl aluminum hydride and diisobutyl aluminum hydride; the halogen compound is one of diethyl aluminum chloride, dipropyl aluminum chloride, diisopropyl aluminum chloride, dibutyl aluminum chloride, diisobutyl aluminum chloride and sesquiethyl aluminum chloride.

[0025] The method for preparing the branched rare earth catalyst of the present invention can be, for example, adding rare earth carboxylate, alkyl aluminum, alkyl aluminum hydride, branching agent and halogen compound into a solvent, mixing evenly, and aging at room temperature for 0.2h to 2h to obtain the branched rare earth catalyst. The molar ratio of the branching agent to the rare earth catalyst can be 1:1 to 10:1.

[0026] In the polymerization process of long-chain branched polybutadiene, the amount of branched rare earth catalyst added is measured by the molar ratio of rare earth carboxylate to butadiene monomer, and the molar ratio of rare earth carboxylate to butadiene monomer is 2×10 -5 ~2×10 -4 :1.

[0027] In the process of preparing the rare earth catalyst, the branching agent is aged together with the rare earth carboxylate neodymium, alkyl aluminum and the like which play a catalytic role. Compared with adding the branching agent to the system after the rare earth catalyst is added to the polymerization system to polymerize into a macromolecule, the technical effect achieved is better. On the one hand, the branching agent can be used as a large sterically hindered ligand. The large volume of steric hindrance destroys the association of the rare earth neodymium and avoids the catalyst from forming heterogeneous particle precipitation. In industrial production, the heterogeneous catalyst is easy to block the pipeline due to precipitation, resulting in 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.

[0028] The method for preparing branched rare earth cis-1,4-butadiene rubber disclosed in the present invention can synthesize a polymer with a cis-1,4-structure content greater than 98%, an adjustable weight average molecular weight within the range of 200,000 to 1,000,000, a branching coefficient of 2.0 to 3.5, and a rubber viscosity (SV) of 100 to 300 mPa·S.

[0029] The preparation method of branched rare earth cis-1,4-butadiene rubber disclosed in the present invention comprises a branching agent which is a butadiene / styrene copolymer containing a functional group, and a rare earth catalyst which has high catalytic activity, and can obtain a polymer product with high conversion rate and high cis-1,4-structure content. Without reducing the cis-1,4-structure content of the polymer, branching can significantly reduce the solution viscosity of the polymer, bringing convenience to processes such as heat transfer, transportation, glue spraying and coagulation in production.

[0030] Containing a certain number of functional groups can increase the polarity of rubber, improve the compatibility of non-polar rubber and white carbon black, and bring good tensile strength, flexural resistance and other properties.

[0031] The use of the rubber branching agent of the present invention to modify the rare earth cis-1,1-butadiene rubber can not only reduce the viscosity of the rubber solution during the polymerization process, but also introduce more functional groups into the molecular chain. These functional groups can increase the dispersion of reinforcing fillers, especially white carbon black, in the rubber matrix, and improve the strength and flexural resistance of the cis-1,1-butadiene rubber. The synthesized cis-1,1-butadiene rubber is suitable for use as a rubber for the sidewall and tread of high-performance tires. DETAILED DESCRIPTION

[0032] The inventors referred to CN1342718A and added a 3d group transition metal organic compound (such as nickel neodecanoate) during the catalyst preparation process, and the intrinsic viscosity of the polymer was reduced from 7.5 dL / g to 5.3 dL / g. However, this operation caused the cis-1,4-structure content of the polyisoprene structural unit to drop from 98.9% to 97.6%.

[0033] The inventors refer to CN202110838519.7 and CN202210011239.3, and use a rare earth catalyst system two-step method to obtain a star-shaped branched rare earth rubber with a rare earth core and a branched chain structure. The synthesized rubber is a star-shaped structure, which does not belong to the long-chain branched type, and the catalyst used is a cyclopentadienyl rare earth complex as the main catalyst, and an organic boron reagent is used. The catalyst synthesis is cumbersome and the price is relatively expensive.

[0034] The inventors prepared branched rare earth isoprene rubber with reference to CN201310165531.1. The branching agent used is liquid rubber, does not contain functional groups, and has no interaction with rubber / filler dispersion.

[0035] The inventors conducted relevant experiments with reference to CN102115509A and US20040102589A1, but since they did not contain functional groups, the results were not as expected by the inventors.

[0036] In view of the fact that the existing technologies cannot meet the expectations of the inventors, the present invention was made after further research and development.

[0037] The raw materials used in the examples of the present invention are all industrial polymer grade and used after purification, without other special requirements. The results of the examples and comparative examples are listed in Table 1. The branching coefficient test method is g=ML 1+4 100℃ *10 / SV,ML 1+4 100℃ is the Mooney viscosity of the glue sample, SV is the dynamic viscosity of the glue during the polymerization process, in mPa·S, and is tested using an online viscometer (in this embodiment, a Sofar online viscometer is used for testing).

[0038] The inventor attempted to prepare rare earth cis-1,1-butadiene rubber using functionalized butadiene / styrene copolymer as a branching agent. Wherein, Bd is a polymerized butadiene unit; Based on amine-containing N,N-dialkylaminostyrene compounds, a variety of compounds were synthesized. Experiments have shown that when other carbon chains are added to the structural formula, such as the compound of structural formula (2) disclosed in CN201280040736.0 as a branching agent, the conversion rate will be significantly reduced and the synthesis price of the compound will be significantly increased.

[0039] In the following examples, the catalyst without a branching agent is referred to as a rare earth catalyst, and the catalyst containing a branching agent is referred to as a branched rare earth catalyst.

[0040] Embodiment 1:

[0041] (1) Preparation of branching agent: A 1L reactor with a jacket was purged with argon and the system was replaced three times. 240 g of hexane, 0.2 g of tetrahydrofuran, 59.4 g of butadiene, 0.6 g of N,N-dimethylaminostyrene, and 30 mmol of n-butyl lithium were added to the reactor, and the temperature was raised to 60°C and polymerized for 50 min. After the monomers were completely converted, the reaction was terminated and set aside.

[0042] Prepare a branching agent represented by formula (I), wherein R1 and R2 are both methyl groups; the polymer number average molecular weight is 2000, It is an N,N-dimethylaminostyrene compound containing amine, St is styrene, and its content in the branching agent copolymer is 1%, and Bd is a butadiene polymerization unit.

[0043] (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 branching agent prepared in step (1) were mixed in the order of hexane + neodymium isooctanoate + triisobutylaluminum + diethylaluminum hydride + branching agent + diethylaluminum chloride, and aged at room temperature for 1 h to obtain a branched rare earth catalyst for standby use.

[0044] 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. The amount of the catalyst was calculated based on the molar ratio of the main catalyst neodymium isooctanoate to butadiene, which was 1×10 -4, polymerize at 70°C for 3 hours, and add 1wt% 2,6-di-tert-butyl-p-methylphenol ethanol solution to terminate the reaction. The rubber solution is wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)n is a polybutadiene branch chain with a number average molecular weight of 10,000 and a branch number m of 20; is the main chain, with a number average molecular weight of 2000, wherein, It is an N,N-dimethylaminostyrene compound containing amine, and its content in the main chain copolymer is 1%. Bd is a butadiene polymerization unit.

[0045] Comparative Example 1:

[0046] The other process conditions and the amount of raw materials added are the same as those in Example 1, except that no branching agent is added during the aging process to obtain a universal rare earth butadiene rubber product.

[0047] Embodiment 2:

[0048] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was introduced to replace the system three times. 420 g of octane, 0.02 g of pentamethyldivinyltriamine, 57 g of butadiene, 3 g of N,N-diethylaminostyrene, and 7.5 mmol of n-butyllithium were added to the reactor, and the temperature was raised to 70°C. The polymerization was carried out for 60 min. After the monomers were completely converted, the reaction was terminated and the reaction was set aside.

[0049] The prepared branching agent is a polymer represented by formula (I), wherein R1 and R2 are both ethyl groups; the polymer has a number average molecular weight of 8000, wherein It is an N,N-diethylaminostyrene compound containing amine, and its content in the branching agent copolymer is 5%. Bd is a butadiene polymerization unit.

[0050] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 50 mL of octane 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 branching agent prepared in step 1 were added. The mixture was mixed in the order of octane + neodymium nonanoate + triisobutylaluminum + diethylaluminum hydride + branching agent + diethylaluminum chloride, and then aged at 50° C. for 30 min to obtain a branched rare earth catalyst for later use.

[0051] 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 catalyst solution prepared above was added. The amount was calculated based on the molar ratio of the main catalyst neodymium to butadiene. The molar ratio of neodymium nonanoate to butadiene was 5×10 -5, polymerized at 60°C for 4 hours, and 1 wt% of an antioxidant 1076 [3,5-di-tert-butyl-4-hydroxyphenylpropionic acid octadecyl] ethanol solution was added to terminate the reaction. The rubber solution was wet coagulated and dried to obtain a long-chain branched rare earth butadiene rubber. The long-chain branched rare earth butadiene rubber is shown in formula (II), wherein (Bd1)n is a polybutadiene branch chain with a number average molecular weight of 14000 and a branch number m of 25; is the main chain, with a number average molecular weight of 8000, among which, It is an N,N-diethylaminostyrene compound containing amine, and its content in the main chain copolymer is 5%. Bd is a butadiene polymerization unit.

[0052] Comparative Example 2:

[0053] The other process conditions and the amount of raw materials added are the same as those in Example 2, except that the branching agent uses a non-functionalized butadiene polymer, that is, N,N-diethylaminostyrene is not added in the branching agent preparation step to obtain a linear butadiene polymer.

[0054] Embodiment 3:

[0055] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was introduced to replace the system three times. 560 g of cyclohexane, 0.15 g of diethylene glycol dimethyl ether, 55.2 g of butadiene, 4.8 g of N,N-di-tert-butylaminostyrene, and 5 mmol of n-butyl lithium were accurately added to the reactor, and the temperature was raised to 80°C and polymerized for 50 min. After the monomers were completely converted, the reaction was terminated and the reaction was set aside.

[0056] The prepared branching agent is a polymer represented by formula (I), wherein R1 and R2 are both tert-butyl groups; the polymer has a number average molecular weight of 12,000, wherein It is an N,N-dibutylaminostyrene compound containing amine, and its content in the branching agent copolymer is 8%. Bd is a butadiene polymerization unit.

[0057] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, 95 mL of cyclohexane was added to a dry catalyst preparation bottle, followed by 0.02 mmol of neodymium neodecanoate, 0.8 mmol of diisobutylaluminum hydride, 0.04 mmol of sesquiethylaluminum chloride, and 0.18 mmol of the branching agent prepared in step 1. The mixture was mixed in the order of cyclohexane + neodymium neodecanoate + diethylaluminum hydride + branching agent + sesquiethylaluminum chloride, and then aged at room temperature for 1 h to obtain a branched rare earth catalyst for later use.

[0058] 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 catalyst solution prepared above was added. The amount was calculated based on the molar ratio of the main catalyst neodymium neodecanoate to butadiene, which was 2×10 -5 , polymerized at 70°C for 3 hours, and 1 wt% of an antioxidant 1076 [3,5-di-tert-butyl-4-hydroxyphenylpropionic acid octadecyl] in ethanol solution was added 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)n is a polybutadiene branch chain with a number average molecular weight of 18,000 and a branch number m of 30; is the main chain, with a number average molecular weight of 8000, among which, It is an N,N-dibutylaminostyrene compound containing amine, and its content in the main chain copolymer is 8%. Bd is a butadiene polymerization unit.

[0059] Comparative Example 3:

[0060] The other process conditions and the amount of raw materials added are the same as those in Example 3, except that the branching agent is carboxyl-terminated polybutadiene rubber with carboxyl functional groups at both ends.

[0061] Embodiment 4:

[0062] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was introduced to replace the system three times. 280 g of cyclopentane, 0.09 g of tetrahydrofurfuryl ether, 54 g of butadiene, 6 g of N,N-dimethylaminostyrene, and 3.33 mmol of n-butyl lithium were added to the reactor, and the temperature was raised to 80°C. The polymerization was carried out for 50 min. After the monomers were completely converted, the reaction was terminated and the reaction was set aside.

[0063] The prepared branching agent is a polymer represented by formula (I), wherein R1 and R2 are both methyl groups; the polymer has a number average molecular weight of 18,000, wherein It is an N,N-dimethylaminostyrene compound containing amine, and its content in the branching agent copolymer is 10%. Bd is a butadiene polymerization unit.

[0064] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, add 50 mL of hexane to a dry catalyst preparation bottle, then add 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 branching agent prepared in step 1, mix in the order of hexane + neodymium decanoate + tributylaluminum + diethylaluminum hydride + branching agent + dibutylaluminum chloride, and age at room temperature for 1 hour to obtain a branched rare earth catalyst for standby use.

[0065] 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 catalyst solution prepared above was added. The amount was calculated based on the molar ratio of the main catalyst neodymium to butadiene. The molar ratio of neodymium decanoate to butadiene was 2×10 -4 , polymerize at 90°C for 2 hours, and add 1wt% antioxidant 2,6-di-tert-butyl-p-methylphenol ethanol solution to terminate the reaction. The rubber solution is wet coagulated and dried to obtain long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)n is a polybutadiene branch chain with a number average molecular weight of 20,000 and a branch number m of 35; is the main chain, with a number average molecular weight of 2000, wherein, It is an N,N-dimethylaminostyrene compound containing amine, and its content in the main chain copolymer is 10%. Bd is a butadiene polymerization unit.

[0066] Comparative Example 4:

[0067] The other process conditions and the order of adding raw materials are the same as those in Example 4, except that the branching agent is not aged together with the catalyst, the branching agent is added after the polymerization is completed, and the branching agent is prepared in step (1) of Example 4.

[0068] Embodiment 5:

[0069] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was introduced to replace the system three times. 480 g of hexane, 0.35 g of tetrahydrofuran, 52.8 g of butadiene, 7.2 g of N,N-di-tert-butylaminostyrene, and 2.4 mmol of n-butyl lithium were accurately added to the reactor, and the temperature was raised to 90°C and polymerized for 50 min. After the monomers were completely converted, the reaction was terminated and the reaction was set aside.

[0070] The prepared branching agent is a polymer represented by formula (I), wherein R1 and R2 are both ethyl groups; the polymer has a number average molecular weight of 25,000, wherein It is an N,N-diethylaminostyrene compound containing amine, and its content in the copolymer is 12%. Bd is a butadiene polymerization unit.

[0071] (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 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 branching agent prepared in step 1. The mixture was mixed in the order of hexane + neodymium isooctanoate + triethylaluminum + diethylaluminum hydride + branching agent + dibutylaluminum chloride, and then aged at room temperature for 0.5 h to obtain a branched rare earth catalyst for later use.

[0072] 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 catalyst solution prepared above was added. The amount was calculated based on the molar ratio of the main catalyst neodymium to butadiene. The molar ratio of neodymium isooctanoate to butadiene was 1×10 -4 , polymerize at 80°C for 3 hours, and add 1wt% antioxidant 2,6-di-tert-butyl-p-methylphenol ethanol solution to terminate the reaction. The rubber solution is wet coagulated and dried to obtain long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd1)n is a polybutadiene branch chain with a number average molecular weight of 15000 and a branch number m of 40; is the main chain, with a number average molecular weight of 25,000, of which, It is an N,N-diethylaminostyrene compound containing amine, and its content in the main chain copolymer is 12%. Bd is a butadiene polymerization unit.

[0073] Comparative Example 5:

[0074] The other process conditions and the order of adding raw materials are the same as those in Example 5, except that the branching agent is not aged together with the catalyst, the branching agent is added after the polymerization is completed, and the type of the branching agent is carboxyl-terminated polybutadiene rubber.

[0075] Embodiment 6:

[0076] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was introduced to replace the system three times. 420 g of cyclohexane, 0.24 g of tetrahydrofuran, 51 g of butadiene, 9 g of N,N-di-tert-butylaminostyrene, and 2 mmol of n-butyl lithium were added to the reactor, and the temperature was raised to 80°C and polymerized for 50 min. After the monomers were completely converted, the reaction was terminated and the reaction was set aside.

[0077] The prepared branching agent is a polymer represented by formula (I), wherein R1 and R2 are both tert-butyl groups; the polymer has a number average molecular weight of 30,000, wherein It is an amine-containing N,N-dibutylaminostyrene compound, the content of which in the copolymer is 15%, and Bd is a butadiene polymerization unit.

[0078] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, add 80 mL of hexane to a dry catalyst preparation bottle, then add 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 branching agent prepared in step 1, mix in the order of hexane + neodymium decanoate + tributylaluminum + diethylaluminum hydride + branching agent + dibutylaluminum chloride, and age at room temperature for 0.6 h to obtain a branched rare earth catalyst for standby use.

[0079] 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 catalyst solution prepared above was added. The amount was calculated based on the molar ratio of the main catalyst neodymium to butadiene. The molar ratio of neodymium decanoate to butadiene was 5×10 -4 , polymerized at 70°C for 3.5 hours, and a 1wt% ethanol solution of antioxidant TNPP was added 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)n is a polybutadiene branch chain with a number average molecular weight of 18,000 and a branch number m of 30; is the main chain, with a number average molecular weight of 30,000, of which, It is an N,N-dibutylaminostyrene compound containing amine, and its content in the main chain copolymer is 15%. Bd is a butadiene polymerization unit.

[0080] Comparative Example 6:

[0081] The other process conditions and the order of adding raw materials are the same as those in Example 6, except that the branching agent is not aged together with the catalyst, the branching agent is added after the polymerization is completed, and the type of the branching agent is liquid isoprene rubber.

[0082] Table 1 Physical properties and dynamic mechanical properties of the embodiments and comparative examples

[0083]

[0084]

[0085] The results in Table 1 show that the content of cis-1,4 structure of the long-chain branched rare earth butadiene rubber synthesized by the present invention is above 98%, the branching coefficient is between 2.01-3.16 (a high branching coefficient indicates a good branching effect), and the viscosity of the rubber is significantly lower than that of the unbranched and different branched cases of the comparative examples. Since the branching also carries functional groups, the tensile strength and rolling resistance (Tanδ at 60°C can represent the rolling resistance, and the lower the value, the more favorable it is) are significantly better than the unbranched and branched cases disclosed in the comparative examples. It can be seen from Example 1 and Comparative Example 1 that the viscosity of the rubber is reduced from 355mPa.S to 261mPa.S after branching, which is beneficial to the transportation and post-processing of the polymerization process. At the same time, the tensile strength is improved, and Tanδ (60°C) is significantly reduced, indicating that the rolling resistance is low, which is beneficial to fuel saving. From Example 2-3 and Comparative Example 2-3, it can be seen that in the case of branching, the amine functional group containing the functional group can promote the dispersion of carbon black / white carbon black in the rubber, so the tensile strength is improved, and Tanδ (60°C) is significantly reduced, indicating that the rolling resistance is low, which is beneficial to fuel saving. From Example 4-6 and Comparative Example 4-6, it can be seen that compared with adding the branching agent to the polymerization system after aging with the catalyst and adding the branching agent to the system at the late stage of polymerization, the branching coefficient of the embodiment is higher, the viscosity of the rubber is lower, and the rolling resistance performance is better.

[0086] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A functionalized rubber branching agent, characterized in that: The branching agent is a functionalized butadiene / styrene copolymer, the structure of which is shown in formula (I): Wherein, Bd is a polymerized butadiene unit; The invention is an N,N-dialkylamino styrene compound containing amine, the content of which in the branching agent is 1-15%, and R1 and R2 are each independently selected from an alkyl group having 1-4 carbon atoms.

2. The functionalized rubber branching agent according to claim 1, characterized in that The number average molecular weight of the copolymer is 2000-30000, and the molecular weight distribution is 1.2-2.

0.

3. A method for preparing the functionalized rubber branching agent according to any one of claims 1 and 2, characterized in that: include: Butadiene, styrene derivative monomers and a structure regulator are mixed and polymerized using alkyl lithium as an initiator.

4. The method according to claim 3, characterized in that The styrene derivative monomer is N,N-dialkylaminostyrene.

5. Use of the functionalized rubber branching agent according to any one of claims 1 or 2 in the preparation of long-chain branched rare earth butadiene rubber.

6. 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, and m is the number of branches, which is selected from a natural number of 20-40; is the main chain, wherein Bd is a butadiene polymerization unit, It is an N,N-dialkylamino styrene compound containing amine, the content of which in the main chain is 1-15%, and R1 and R2 are each independently selected from an alkyl group with 1-4 carbon atoms.

7. The long-chain branched rare earth butadiene rubber according to claim 6, characterized in that: Bd1 is a polybutadiene rubber branched chain with a number average molecular weight of 10000-20000; It is the main chain and has a number average molecular weight of 2000-30000.

8. A method for preparing the long-chain branched rare earth butadiene rubber according to any one of claims 6 or 7, characterized in that: include: Long-chain branched rare earth cis-1,1-butadiene is prepared by coordination polymerization under the action of a branched rare earth catalyst, wherein the branched rare earth catalyst contains the functionalized rubber branching agent according to any one of claims 1 or 2.

9. The method of claim 8, characterized in that The branched rare earth catalyst is prepared by sequentially adding neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, the functionalized rubber branching agent according to any one of claims 1 or 2, and alkyl aluminum halide into a solvent, and aging the solvent.

10. The method according to claim 9, characterized in that 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.

11. Use of the long-chain branched rare earth butadiene rubber according to any one of claims 6 or 7 in the preparation of tires.

12. A tire, characterized in that: Comprising the long-chain branched rare earth butadiene rubber as described in any one of claims 6 or 7.

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