Functionalized isoprene branching agent as well as preparation and application thereof

Abstract

The invention discloses a functionalized isoprene branching agent, the functionalized isoprene branching agent is a functionalized isoprene polymer, the structure of the functionalized isoprene branching agent is (I) n-R, in the formula (I), n is an isoprene homopolymer, and R is carried groups such as silica, amido, anilino, nitrogen heterocyclic ring and the like. The invention also discloses a preparation method and application thereof. The rare earth butadiene rubber functionalized branching agent is used for modifying rare earth butadiene rubber, branching not only can reduce the viscosity of a rubber solution in the polymerization process, but also can bring more functional groups 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 and tear resistance of 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 isoprene branching agent and a preparation method and application thereof. Background Art

[0002] Butadiene rubber is widely used in tire, tape, hose, rubber shoes and other manufacturing industries due to its advantages of high elasticity, low heat generation, low temperature resistance, low rolling resistance, flex resistance, wear resistance, water resistance, etc., easy polymerization process, and cheap and easy-to-obtain raw materials. 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, improve tire wear resistance, durability and high-speed performance, and 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 greater than that of other types of butadiene rubber with the same Mooney. The high viscosity of the rubber increases the difficulty of engineering production, brings difficulties to polymer transportation and drying, and also makes the processing performance worse. Compared with linear rare earth rubber materials, branched rare earth rubber materials, due to their unique physical and chemical properties and branched structure, have the ability to obtain high molecular weight polymers while maintaining low melt and solution viscosities, thus achieving the unity of their physical and mechanical properties and processing properties at a lower viscosity of the rubber solution.

[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.

[0004] Butadiene rubber is mainly used for the sidewall of tires. For sidewall materials, tear strength is an important performance indicator. How to improve the tear strength of butadiene rubber has always been the research focus in this field. By increasing the crosslinking density through the effect of branching points, the tear strength can be effectively improved. At the same time, as a tire material, white carbon black has become the most widely used reinforcing filler in tire materials. There is no polar group in the molecular chain of butadiene rubber. During processing, it has poor compatibility with white carbon black, and the Payne effect is significant, and the mechanical properties are significantly reduced. Introducing a certain amount of functional groups in the branching agent, enhancing the polarity of the molecular chain of butadiene rubber, improving the compatibility of butadiene rubber and reinforcing fillers, can improve the tear strength of the product. Summary of the invention

[0005] The inventors found that the existing rare earth butadiene rubber polymer has a high viscosity and poor interaction with silica, resulting in the tear strength performance of the rubber product failing to meet expectations. After further research and development, the present invention was made.

[0006] As one aspect of the present invention, it relates to a functionalized isoprene branching agent, wherein the branching agent is a functionalized isoprene polymer, as shown in formula (1),

[0007] (I) n -R

[0008]

[0009] Wherein (I)n is an isoprene homopolymer, R is a group with siloxane, amine, aniline and / or nitrogen-containing heterocyclic ring, and the polymer has a number average molecular weight of 3000-20000 and a molecular weight distribution of 1.1-2.0.

[0010] As another aspect of the present invention, it relates to a method for preparing the above functionalized isoprene branching agent, comprising: mixing isoprene, a solvent (such as hexane, cyclohexane, cyclopentane, etc.) and a structure regulator (such as tetrahydrofuran, diethylene glycol dimethyl ether, etc.), using alkyl lithium (such as n-butyl lithium) as an initiator, polymerizing, and after the polymerization conversion rate reaches 100%, adding a capping agent (such as siloxanes, aminobenzophenones, Schiff base compounds, etc.) to carry out a capping reaction. The structure regulator can increase the 3,4-% structure content of the isoprene unit.

[0011] As another aspect of the present invention, it relates to the use of the functionalized isoprene branching agent in the preparation of long-chain branched rare earth butadiene rubber.

[0012] As another aspect of the present invention, it relates to a long-chain branched rare earth butadiene rubber, as shown in formula (2),

[0013]

[0014] (2)

[0015] Wherein, Bd is a polybutadiene rubber branch chain (in a specific embodiment, the number average molecular weight is 10000-20000); m is the number of branches, selected from a natural number of 20-40; (I) n -R is the main chain (in a specific embodiment, the number average molecular weight is 3000-20000), wherein (I) n It is an isoprene polymerization unit, and R is a group carrying silicon oxygen, amine, aniline and / or nitrogen-containing heterocyclic ring.

[0016] 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 functionalized isoprene branching agent. The rare earth catalyst is prepared by adding neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, the above-mentioned functionalized isoprene branching agent, and alkyl aluminum halide to a solvent in sequence and aging. 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.

[0017] 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.

[0018] As another aspect of the present invention, it relates to a tire, comprising the long-chain branched rare earth butadiene rubber.

[0019] 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 structural regulator, isoprene is used as a reaction monomer, and a capping agent containing a functional group is used to carry out a capping reaction to synthesize a branching agent with a functional group in the chain, (I) n -R, (I)n is an isoprene homopolymer, and R is a group with silicon oxygen, amine, aniline, nitrogen-containing heterocyclic ring, etc. The branching agent and butadiene are used in the presence of a rare earth catalyst to prepare a long-chain branched rare earth cis-butadiene rubber through coordination polymerization. The present invention not only reduces the viscosity of the polymerized rubber during the polymerization process, but also uses low molecular weight isoprene as a branching point to increase the crosslinking density. The functional groups contained in the invention increase the interaction between polar butadiene rubber and carbon black / white carbon black, thereby ensuring high tear strength of the butadiene rubber.

[0020] The percentages described in the present invention all refer to mass percentages.

[0021] In a specific embodiment, the preparation method of the functionalized isoprene branching agent may include the following steps: first, in a stainless steel reactor with a jacket, argon is replaced 2 to 4 times, 300% to 800% of solvent, isoprene monomer and 0.01% to 0.5% of polarity regulator are added to the polymerization reactor in sequence, and an alkyl lithium initiator is added, the reaction temperature is 50° C. to 90° C., and the reaction pressure is 0.1 MPa to 0.4 MPa. a, the reaction time is 50min-80min; after there is no free monomer in the polymerization reaction, a capping agent is added, the capping agent is a compound with siloxane, aminobenzophenone, Schiff base compound, nitrogen-containing heterocycle and the like that can react with active lithium, the molar ratio of the capping agent to the alkyl lithium is 1.0-1.2, the capping temperature is 60℃-80℃, the time is 20min-60min, and after the reaction is completed, a branching agent with functional groups such as siloxane, amino, aniline, and nitrogen heterocycle is obtained.

[0022] In a specific embodiment, the preparation method of the long-chain branched butadiene rubber may include the following steps: based on 100% of the total mass of the reaction monomers, first, in a stainless steel reactor with a jacket, argon is replaced 2 to 4 times, 200% to 800% of the solvent and butadiene monomer are added to the polymerization kettle, and the aged rare earth catalyst and branching agent are added to the polymerization kettle to initiate the polymerization reaction. The reaction temperature is 50°C to 80°C, the reaction pressure is 0.2MPa to 0.4MPa, and the reaction time is 120min to 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.

[0023] 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 preferred hydrocarbon solvents include straight-chain alkanes, cycloalkanes and aromatic hydrocarbons, such as hexane, octane, heptane, cyclohexane, benzene, toluene, ethylbenzene 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.

[0024] 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.

[0025] In the polymerization system for preparing the branching agent of the present invention, 0.01% to 0.5% of a polar organic compound is added as a polarity regulator to cause the alkyl lithium initiator to produce a polarization or solvation effect, reduce its association degree, and increase the initiation reaction rate of a positive initiator such as n-butyl lithium. At the same time, the regulator can increase the content of the 3,4 structure in the isoprene 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.

[0026] The end-capping agent used in the preparation of the branching agent of the present invention is selected from the following categories: (1) siloxane containing chlorine atoms ClSi(OR) 3 , where OR is a non-hydrolyzable alkoxy group with 4 to 20 carbon atoms; (2) aminobenzophenones, such as 4,4-bis(dimethylamino)benzophenone, 4,4-bis(diethylamino)benzophenone, etc.; (3) Schiff bases, such as N,N-dimethylaminobenzaldehyde condensate; (4) nitrogen-containing heterocyclics, such as cyclopentylimide. The end-capping agent containing the above functional groups reacts with the active chain P to introduce groups containing silicon oxygen, amino, anilino, etc. into the polymer, thereby obtaining a polymer containing functional groups. The amount of the above end-capping agent used depends on the amount of the initiator, and the general molar ratio of the amount to the organic lithium is 1.0 to 1.2.

[0027] The invention discloses a method for preparing branched rare earth cis-1,2-dimethylbutyl rubber, wherein the rare earth catalyst is composed of rare earth carboxylate, alkyl aluminum and halogen compound in a certain molar ratio. 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] By using the preparation method of branched rare earth butadiene rubber disclosed in the present invention, 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 solution viscosity (η) of 1.2 dL / g to 3.0 dL / g can be synthesized.

[0032] The invention discloses a method for preparing branched rare earth cis-1,4-butadiene rubber, wherein the branching agent is a low molecular weight isoprene polymer containing a functional group, and the rare earth catalyst has high catalytic activity and can obtain a polymer product with a high conversion rate and a 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, while the functional group can increase the polarity of the rubber, improve the compatibility of the non-polar rubber with carbon black / white carbon black, and the isoprene branching can effectively improve the tear resistance of the cis-1,4-butadiene rubber. DETAILED DESCRIPTION

[0033] 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%.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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 sample, SV is the dynamic viscosity of the sample, in mPa·S. The intrinsic viscosity of the polymerized glue was measured using an Ubbelohde viscometer at 25°C, with toluene as the solvent, and the calculation formula is [η] = [2(η sp -lnη r )] 1 / 2 / c, where η r =t / t 0 , η sp =η r -1, t is the flow time of the polymer toluene solution with a concentration of c, t 0 is the flow time of toluene.

[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: In a 1L reactor with a jacket, argon was passed through the system to replace it three times. 240 g of hexane, 0.2 g of tetrahydrofuran, 60 g of isoprene, and 20 mmol of n-butyl lithium were added to the polymerization reactor. The temperature was raised to 60°C and the polymerization was carried out for 50 min. After the monomers were completely converted, 20 mmol of γ-chloropropyltrimethoxysilane capping agent was added to carry out the capping reaction. The reaction temperature was 60°C and the reaction time was 60 min. After the capping reaction was completed, the reaction was terminated and set aside.

[0042] The prepared branching agent is a polymer represented by formula (I), wherein R is propyltrimethoxysilane; the polymer number average molecular weight is 3000, (I) n It is an isoprene 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 + aluminum + aluminum hydride + branching agent + aluminum chloride, and aged at room temperature for 1 hour to obtain a branched rare earth catalyst for 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 calculated amount of the catalyst solution prepared above was added. The molar ratio of neodymium isooctanoate to butadiene was 1×10 -4 , polymerize at 60-70°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 long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd)n is a polybutadiene branch chain with a number average molecular weight of 10,000 and a branch number m of 20; (I) n -R is the main chain, R is propyltrimethoxysilane, and the number average molecular weight is 3000.

[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 passed through the system to replace it three times. 420 g of hexane, 0.02 g of pentamethyldivinyltriamine, 60 g of isoprene, and 12 mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 70°C. The polymerization was carried out for 60 min. After the monomers were completely converted, 12 mmol of 3-chloropropyltriethoxysilane capping agent was added at once for capping reaction. The capping temperature was 70°C and the reaction time was 50 min. After the reaction was completed, the reaction was terminated and set aside.

[0049] The prepared branching agent is a polymer represented by formula (I), wherein R is propyltriethoxysilane; the polymer number average molecular weight is 5000, (I) n It is an isoprene polymerization unit.

[0050] (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 0.04 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, mix them evenly in a certain order, and age them at 50° C. for 30 min to obtain a branched rare earth catalyst for 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 calculated amount of the catalyst solution prepared above was added. 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] 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 (Bd)n is a polybutadiene branch chain with a number average molecular weight of 14,000 and a branch number m of 25; (I) n -R is the main chain, R is propyltriethoxysilane, and the number average molecular weight is 5000.

[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 isoprene polymer, that is, no functionalized end-capping agent is added in the branching agent preparation step to obtain a linear isoprene polymer.

[0054] Embodiment 3:

[0055] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was passed through the system to replace it three times. 560 g of cyclohexane, 0.15 g of diethylene glycol dimethyl ether, 70 g of isoprene, and 8.75 mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 80°C. The polymerization was carried out for 50 min. After the monomers were completely converted, 8.75 mmol of 4,4-bis(dimethylamino)benzophenone was added at once for end-capping reaction. The end-capping reaction temperature was 80°C and the reaction time was 20 min. After the reaction was completed, the reaction was terminated and used for later use.

[0056] The prepared branching agent is a polymer represented by formula (I), wherein R is 4-bis(dimethylamino)diphenylmethyl; the polymer number average molecular weight is 8000, (I) n It is an isoprene polymerization unit.

[0057] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, add 95 mL of hexane to a dry catalyst preparation bottle, then add 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. After mixing well, age at room temperature for 1 hour to obtain a branched rare earth catalyst for 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 calculated amount of the catalyst solution prepared above was added. The molar ratio of neodymium neodecanoate to butadiene 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 (Bd)n is a polybutadiene branch chain with a number average molecular weight of 18,000 and a branch number m of 30; (I) n -R is the main chain, R is 4-bis(dimethylamino)diphenylmethyl, and the number average molecular weight is 8000.

[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 functionalized polybutadiene rubber.

[0061] Embodiment 4:

[0062] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was passed through the system to replace it three times. 280 g of cyclopentane, 0.09 g of tetrahydrofurfuryl ether, 70 g of isoprene, and 5.8 mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 80°C. The polymerization was carried out for 50 min. After the monomers were completely converted, 5.8 mmol of 4,4-bis(diethylamino)benzophenone capping agent was added at once for capping reaction. The capping temperature was 70°C and the reaction time was 4 min. After the capping reaction was completed, the reaction was terminated and set aside.

[0063] The prepared branching agent is a polymer represented by formula (I), wherein R is 4-bis(diethylamino)diphenylmethyl; the polymer number average molecular weight is 12000, (I) n It is an isoprene 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 well, and age at room temperature for 1 h to obtain a branched rare earth catalyst for 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 calculated amount of the catalyst solution prepared above was added. The molar ratio of neodymium decanoate to butadiene was 2×10 -4 , polymerized at 90°C for 2 hours, and then 1 wt% antioxidant 2,6-di-tert-butyl-p-methylphenol ethanol solution was added to terminate the reaction. The rubber solution was wet coagulated and dried to obtain long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd)n is a polybutadiene branch chain with a number average molecular weight of 20,000 and a branch number m of 35; (I) n -R is the main chain, R is 4-bis(diethylamino)diphenylmethyl, and the number average molecular weight is 12,000.

[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 passed through the system to replace it three times. 480 g of hexane, 0.35 g of tetrahydrofuran, 80 g of isoprene, and 5 mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 90°C. The polymerization was carried out for 50 min. After the monomers were completely converted, 5 mmol of N, N-dimethylaminobenzaldehyde condensation aniline capping agent was added at once for capping reaction. The coupling temperature was 80°C and the reaction time was 20 min. After the capping reaction was completed, the reaction was terminated and set aside.

[0070] The prepared branching agent is a polymer represented by formula (I), wherein R is N,N-dimethylaminobenzaldehyde condensation aniline group; the polymer number average molecular weight is 16000, (I) n It is an isoprene polymerization unit.

[0071] (2) Preparation of long-chain branched rare earth butadiene rubber: Under argon protection, add 70 mL of cyclohexane to a dry catalyst preparation bottle, then add 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, mix well, and age at room temperature for 0.5 h to obtain a branched rare earth catalyst for standby 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 calculated amount of the catalyst solution prepared above was added. The molar ratio of neodymium isooctanoate to butadiene was 1×10 -4 , polymerized at 80°C for 3 hours, and 1 wt% antioxidant 2,6-di-tert-butyl-p-methylphenol ethanol solution was added to terminate the reaction. The rubber solution was wet coagulated and dried to obtain long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd)n is a polybutadiene branch chain with a number average molecular weight of 15,000 and a branch number m of 40; (I) n -R is the main chain, R is N,N-dimethylaminobenzaldehyde condensation aniline group, and the number average molecular weight is 16000.

[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 dialkyldiolefin silane disclosed in the patent.

[0075] Embodiment 6:

[0076] (1) Preparation of branching agent: In a 1L reactor with a jacket, argon was passed through the system to replace it three times. 420 g of cyclohexane, 0.24 g of tetrahydrofuran, 70 g of isoprene, and 5.6 mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 80°C. The polymerization was carried out for 50 min. After the monomers were completely converted, 0.56 mmol of cyclopentyl imine capping agent was added at once for capping reaction. The capping temperature was 60°C and the reaction time was 60 min. After the capping reaction was completed, the reaction was terminated and set aside.

[0077] The prepared branching agent is a polymer represented by formula (I), wherein R is a cyclopentyl imine group; the polymer number average molecular weight is 20000, (I) n It is an isoprene 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 well, and age at room temperature for 0.6 h to obtain a branched rare earth catalyst for 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 calculated amount of the catalyst solution prepared above was added. The molar ratio of neodymium decanoate to butadiene was 5×10 -4 , polymerized at 70°C for 3.5 hours, and then 1 wt% ethanol solution of antioxidant TNPP was added to terminate the reaction. The rubber solution was wet coagulated and dried to obtain long-chain branched rare earth butadiene rubber as shown in formula (II), wherein (Bd)n is a polybutadiene branch chain with a number average molecular weight of 18,000 and a branch number m of 30; (I) n -R is the main chain, R is a cyclopentylimide group, and the number average molecular weight is 20,000.

[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 the liquid isoprene rubber disclosed in the patent.

[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 2.24-3.22 (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 in the comparative example. Since the branching also carries functional groups, the tensile strength and tear strength are significantly better than the unbranched and branched cases disclosed in the comparative example. It can be seen from the embodiment and the comparative example 1 that the viscosity of the rubber is reduced from 5.84dL / g to 2.48dL / g after branching, which is beneficial to the transportation and post-processing of the polymerization process. At the same time, the tensile strength is increased from 16.4MPa to 18.9MPa, and in particular, the tear strength is increased from 28.2kN·m-1 to 38.5kN·m-1. From Example 2-3 and Comparative Example 2-3, it can be seen that in the presence of branching, the amine functional group containing the functional group can promote the dispersion of carbon black / white carbon black in the rubber, thereby improving the tensile strength and tear strength, which is very beneficial to the tear resistance of the tread rubber. 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 end of the 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 isoprene branching agent, characterized in that: The branching agent is a functionalized isoprene polymer, as shown in formula (1), (I) n -R, (1)， Among them (I) n It is an isoprene homopolymer, and R is a group carrying silicon oxygen, amine, anilino and / or nitrogen-containing heterocyclic ring.

2. The functionalized isoprene branching agent according to claim 1, characterized in that The number average molecular weight of the polymer is 3000-20000, and the molecular weight distribution is 1.1-2.

0.

3. A method for preparing the functionalized isoprene branching agent according to any one of claims 1 or 2, characterized in that: include: Isoprene, a solvent and a structure regulator are mixed, and polymerization is carried out using alkyl lithium as an initiator. After the polymerization is completed, a capping agent is added to carry out a capping reaction.

4. The method according to claim 3, characterized in that The structure regulator is tetrahydrofuran or diethylene glycol dimethyl ether; the alkyl lithium is n-butyl lithium; and the end-capping agent is siloxane containing chlorine atoms, aminobenzophenones, Schiff bases or nitrogen-containing heterocyclics.

5. Use of the functionalized isoprene 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 (2), Wherein, Bd is a polybutadiene rubber branch chain, and m is the number of branches, which is selected from a natural number of 20-40; (I) n -R as the main chain, where (I) n It is an isoprene polymerization unit, and R is a group carrying silicon oxygen, amine, aniline and / or nitrogen-containing heterocyclic ring.

7. The long-chain branched rare earth butadiene rubber according to claim 6, characterized in that: Bd is a polybutadiene rubber branched chain with a number average molecular weight of 10000-20000; (I) n -R is the main chain, and the number average molecular weight is 3000-20000.

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: 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 isoprene 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 isoprene branching agent according to any one of claims 1 or 2, and alkyl aluminum halide into a solvent and aging.

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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