Siloxane functionalized branching agent as well as preparation and application thereof

Abstract

The invention discloses a siloxane functionalized branching agent which is characterized in that the siloxane functionalized branching agent is shown as a formula (I) # imgabs0 #, Bd is a butadiene polymerization unit, # imgabs1 # is a siloxane group containing two alkyl groups of R1 and R2, and R1, R2 and R3 are respectively and independently selected from alkyl groups containing 1-3 carbon atoms. The invention also discloses a preparation method and application thereof. After the butadiene rubber is branched, the viscosity of a rubber solution in a polymerization process can be reduced, functional groups containing siloxane can be introduced into a molecular chain, and the functional groups can enhance the dispersion of a reinforcing filler, particularly white carbon black, in a rubber matrix and improve the strength and heat generation performance 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 siloxane functionalized branching agent and its preparation and application. Background Art

[0002] With the implementation of the EU tire labeling regulations and the rise of new energy vehicles, the tire industry has put forward new requirements for rubber raw materials. In addition to requiring low rolling resistance and good wear resistance of tires, it also requires increasing tire load while reducing tire weight. Butadiene rubber is widely used in the tire industry because of its advantages such as high elasticity, low heat generation, low temperature resistance, low rolling resistance, flexural resistance, wear resistance, water resistance, etc., easy polymerization process operation, and cheap and easy to obtain raw materials. 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, flexural resistance, low heat generation, low rolling resistance, etc., which can reduce tire hysteresis loss and endogenous heat, 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 series, meeting the needs of green tires.

[0003] High Mooney (Mooney viscosity 60-100) rare earth butadiene rubber is significantly superior to ordinary Mooney (Mooney viscosity 40-50) rare earth butadiene rubber in terms of physical and mechanical properties such as strength, tensile stress, and elongation. In the process of making tires, high Mooney (Mooney viscosity 60-100) rare earth butadiene rubber not only has better resilience and compression heat generation, but also has obvious advantages in cut resistance and crack growth resistance; because the vulcanized rubber modulus is low and the Mooney rare earth rubber modulus is high, this is conducive to improving the high temperature controllability of the tread rubber. In addition, in the solution-polymerized styrene butadiene rubber / natural rubber / butadiene rubber three-rubber system, high Mooney (Mooney viscosity 60-100) rare earth butadiene rubber has good comprehensive performance, high dynamic mechanical properties, high thermal oxidation aging performance, and outstanding cut resistance and crack growth resistance. Therefore, the prospects for high Mooney (Mooney viscosity 60-100) rare earth butadiene rubber are very broad. However, 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, 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 have the unique physical and chemical properties and branched structure, which can obtain high molecular weight polymers while maintaining low melt and solution viscosity, and can achieve the unity of its physical and mechanical properties and processing performance at a lower viscosity of the rubber.

[0004] 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.

[0005] Carbon black / white carbon black is the most widely used reinforcing filler in rubber. There is no polar group in the molecular chain of butadiene rubber, and its compatibility with carbon black / white carbon black is poor during processing. The Payne effect is significant, and the mechanical properties are significantly reduced. Introducing a certain amount of functional groups into the branching agent can enhance the polarity of the butadiene rubber molecular chain and improve the compatibility of butadiene rubber with reinforcing fillers, which can also improve the product's cold flow performance, heat generation performance, etc. Summary of the invention

[0006] The inventors found that the existing rare earth butadiene rubber, especially high-gold butadiene rubber, has a high viscosity in the polymerized rubber liquid and poor interaction with silica, resulting in the strength and heat generation performance of the rubber product failing to meet expectations. After further research and development, the present invention was made.

[0007] As one aspect of the present invention, it relates to a siloxane functionalized branching agent, as shown in formula (I),

[0008]

[0009] Wherein, Bd is a butadiene polymerization unit, It is a siloxane group containing two alkyl groups R1 and R2, wherein R1, R2 and R3 are independently selected from alkyl groups containing 1 to 3 carbon atoms and may be the same or different. In a specific embodiment, the number average molecular weight of the siloxane functional branching agent is 2000-50000, and the molecular weight distribution is 1.2-2.0.

[0010] As another aspect of the present invention, it relates to a method for preparing the above-mentioned siloxane functionalized branching agent, comprising: mixing butadiene, a solvent (such as cyclopentane, hexane, 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 conversion is completed, adding hydrogen-containing siloxane and a hydrosilylation catalyst to carry out a hydrosilylation reaction to obtain a polybutadiene polymer containing siloxane groups.

[0011] As another aspect of the present invention, it relates to the use of the above-mentioned siloxane functionalized 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 (II),

[0013]

[0014] 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 2000-50000), wherein Bd is a butadiene polymerization unit, It is a siloxane group containing two alkyl groups, R1 and R2, wherein R1, R2 and R3 are independently selected from alkyl groups containing 1 to 3 carbon atoms and may be the same or different.

[0015] 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 siloxane branching agent. The rare earth catalyst is prepared by adding neodymium carboxylate, alkyl aluminum, alkyl aluminum hydride, the above-mentioned siloxane functionalized 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.

[0016] 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.

[0017] As another aspect of the present invention, it relates to a tire prepared by using the long-chain branched rare earth butadiene rubber.

[0018] The percentages described in the present invention all refer to mass percentages.

[0019] The preparation of the branched butadiene rubber of the present invention is carried out in a reactor, and the specific preparation process comprises the following steps:

[0020] (1) Preparation of branching agent: first, in a stainless steel reactor with a jacket, argon is replaced 2 to 4 times, and 300% to 800% of solvent, butadiene monomer and 0.01% to 0.5% of polarity regulator are added to the polymerization reactor in sequence. The reaction temperature is 50° C. to 90° C., the reaction pressure is 0.1 MPa to 0.25 MPa, and the reaction time is 50 min to 80 min. After no free monomer is present in the polymerization reaction, a certain amount of hydrogen-containing siloxane is added, and a certain amount of hydrosilylation reaction catalyst and auxiliary agent are added to carry out hydrosilylation reaction at 60 to 120° C. for 30 to 120 min. After the reaction is completed, a branching agent containing siloxane in the chain is obtained.

[0021] (2) Preparation of branched butadiene rubber: 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 the 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 mixture is condensed and dried to obtain a long-chain branched rare earth butadiene rubber product.

[0022] The branching agent of the present invention is a functionalized butadiene polymer containing siloxane, and its structure is Wherein, Bd is a butadiene polymerization unit, It is a siloxane group containing two alkyl groups, R1, R2, and R3 are independent alkyl groups containing 1 to 3 carbon atoms, which can be the same or different. The polymer has a number average molecular weight of 2000-50000 and a molecular weight distribution of 1.2-2.0.

[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 an activator to cause the alkyl lithium initiator to produce a polarization or solvation effect, reduce its association degree, and increase the initiation reaction speed of a positive initiator such as n-butyl lithium. At the same time, the activator can increase the content of vinyl in the butadiene unit. Such polar organic compounds include diethylene glycol dimethyl ether (2G), tetrahydrofuran (THF), ether, ethylene glycol dimethyl ether (DME), etc., preferably diethylene glycol dimethyl ether and tetrahydrofuran.

[0026] The general formula of the hydrogen-containing siloxane used in the preparation of the branching agent of the present invention is H-Si(R1, R2)-O-R3; wherein R1, R2 and R3 are alkyl groups containing 1 to 3 carbon atoms, and the three groups can be the same or different; the hydrosilylation reaction catalyst is a compound or complex of a Group VIII metal, such as a compound or complex of platinum, rhodium, iron or nickel, such as a Karstedt catalyst (platinum complex), a Wilkinson catalyst (rhodium complex) and the like; and the addition amount of the hydrosilylation reaction catalyst is 0.1wt% to 20wt% of the long-chain hydrogen-containing siloxane.

[0027] The invention discloses a method for preparing branched rare earth cis-1,2-dimethylbutyl rubber. 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; and 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 of the present invention, 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 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 ligand with large steric hindrance. The large volume of steric hindrance destroys the association of rare earth neodymium and avoids the catalyst from forming heterogeneous particle precipitation. In industrial production, heterogeneous catalysts are prone to block pipelines due to precipitation, resulting in unstable polymerization 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 cis-1,4-butadiene rubber disclosed in the present invention, rare earth cis-1,4-butadiene rubber with a cis-1,4-structure content greater than 98%, a weight average molecular weight adjustable within the range of 500,000 to 1.3 million, and a branching coefficient of 2.0 to 3.2 can be synthesized. The Mooney viscosity of the synthesized cis-1,4-butadiene rubber is greater than 80, and the high Mooney product can be used alone or as an oil-filled product. 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] In order to further illustrate the details of the present invention, several examples are given below, but the invention should not be limited thereto. The raw materials used in the examples 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] 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.

[0039] Embodiment 1:

[0040] Preparation of branching agent: In a 1L reactor with a jacket, argon was passed through the system to replace it three times. 240g of hexane, 0.2g of tetrahydrofuran, 60g of butadiene, and 30mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 60°C. The polymerization was carried out for 50 minutes. After the monomers were completely converted, 100mmol of H-Si-(OCH3)(CH3)2 and 0.5mmol of Karstedt catalyst (platinum complex) were added, and the temperature was raised to 100°C. After the reaction was continued for 1 hour, a branching agent was obtained, which is a polymer shown in formula (I), wherein R1, R2, and R3 are all methyl groups; the number average molecular weight of the polymer is 2000.

[0041] (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 0.03 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, mix them evenly in a certain order, and age them at room temperature for 1 hour to obtain a branched rare earth catalyst for use.

[0042] 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 0.2×10 -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 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, is a group containing siloxane, and Bd is a butadiene polymerization unit.

[0043] Comparative Example 1:

[0044] 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 polymerization process to obtain a universal rare earth butadiene rubber product.

[0045] Embodiment 2:

[0046] (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 butadiene, and 12 mmol of n-butyllithium 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, 80 mmol of H-Si-(OC2H5)(CH3)2 and 0.12 mmol of Wilkinson catalyst (rhodium complex) were added, and the temperature was raised to 90-100°C. The reaction was continued for 1 hour and then the reaction was terminated for use.

[0047] The prepared branching agent is a polymer represented by formula (I), wherein R1, R2 and R3 are all ethyl groups; and the number average molecular weight of the polymer is 5000.

[0048] (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.

[0049] 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 prepared catalyst solution was added. The molar ratio of neodymium nonanoate to butadiene was 2.5×10 -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 (Bd1)n is a polybutadiene branch chain with a number average molecular weight of 14,000 and a branch number m of 25; is the main chain, and the number average molecular weight is 5000, wherein, is a group containing siloxane, and Bd is a butadiene polymerization unit.

[0050] Comparative Example 2:

[0051] Other process conditions and raw material addition amounts are the same as those in Example 2, except that: the branching agent uses a non-functionalized butadiene polymer, that is, no functionalized coupling agent is added in the branching agent preparation step to obtain a linear butadiene polymer.

[0052] Embodiment 3:

[0053] (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, 70 g of butadiene, and 7 mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 80°C and polymerized for 50 min. After the monomers were completely converted, 120 mmol of H-Si-(OC2H5)(C2H5)2 and 0.75 mmol of Wilkinson catalyst (rhodium complex) were added at once, and the temperature was raised to 100°C. The reaction was continued for 1 hour and then the reaction was terminated for use.

[0054] The prepared branching agent is a polymer represented by formula (I), wherein R1, R2 and R3 are all ethyl groups; and the number average molecular weight of the polymer is 10,000.

[0055] (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.

[0056] 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 1.25×10 -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, and the number average molecular weight is 10000, wherein, is a group containing siloxane, and Bd is a butadiene polymerization unit.

[0057] Comparative Example 3:

[0058] 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.

[0059] Embodiment 4:

[0060] (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, 70 g of butadiene, and 3.5 mmol of n-butyl lithium were added to the polymerization reactor, and the temperature was raised to 80°C and polymerized for 50 min. After the monomers were completely converted, 80 mmol of H-Si-(OC3H7)(C3H7)2 and 0.25 mmol of Wilkinson catalyst (rhodium complex) were added at once, and the temperature was raised to 120°C. The reaction was continued for 30 min and then the reaction was terminated for standby use.

[0061] The prepared branching agent is a polymer represented by formula (I), wherein R1, R2 and R3 are all propyl groups; and the number average molecular weight of the polymer is 20,000.

[0062] (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.

[0063] 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 prepared catalyst solution was added. The molar ratio of neodymium decanoate to butadiene was 1×10 -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, and the number average molecular weight is 20000, wherein, is a group containing siloxane, and Bd is a butadiene polymerization unit.

[0064] Comparative Example 4:

[0065] 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.

[0066] Embodiment 5:

[0067] (2) 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, 80 g of butadiene, and 2.7 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, 170 mmol of H-Si-(OC3H7)(C3H7)2 and 0.4 mmol of Wilkinson catalyst (rhodium complex) were added at once, and the temperature was maintained at 90°C. The reaction was continued for 1 hour and then the reaction was terminated for use.

[0068] The prepared branching agent is a polymer represented by formula (I), wherein R1, R 2、 R3 is propyl; the number average molecular weight of the polymer is 30,000.

[0069] (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.

[0070] 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 prepared catalyst solution was added. The molar ratio of neodymium isooctanoate to butadiene was 0.5×10 -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 30,000, of which, is a group containing siloxane, and Bd is a butadiene polymerization unit.

[0071] Comparative Example 5:

[0072] 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.

[0073] Embodiment 6:

[0074] (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, 70 g of butadiene, and 1.4 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, 220 mmol of H-Si-(OCH3)(C3H7)2 and 0.28 mmol of Wilkinson catalyst (rhodium complex) were added at once, the temperature was raised to 100°C, and the reaction was continued for 1 hour before the reaction was terminated for use.

[0075] The prepared branching agent is a polymer represented by formula (I), wherein R1 and R2 are both propyl groups, and R3 is methyl; the number average molecular weight of the polymer is 50,000.

[0076] (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.

[0077] 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 1.5×10 -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 (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, and the number average molecular weight is 50,000, wherein, is a group containing siloxane, and Bd is a butadiene polymerization unit.

[0078] Comparative Example 6:

[0079] 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.

[0080] Table 1 Physical properties and dynamic mechanical properties of the embodiments and comparative examples

[0081]

[0082]

[0083] The results of Table 1 show that the Mooney viscosity of the long-chain branched rare earth cis-butadiene rubber synthesized by the present invention is above 80, the content of cis-1,4 structure is above 98%, the branching coefficient is between 2.02-3.02 (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 compression fatigue temperature rise (which can represent heat generation, the lower the more beneficial) 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 after branching is reduced from 642mPa.S to 452mPa.S, which is beneficial to solving the transportation and post-processing of the polymerization process. At the same time, the tensile strength is improved, and the compression fatigue temperature rise is reduced from 27.7℃ to 18.6℃, indicating that the heat generation is reduced. It can be seen from Example 2-3 and Comparative Example 2-3 that in the case of branching, the amino 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 the heat generation is reduced. It can be seen from Example 4-6 and Comparative Example 4-6 that compared with adding the branching agent to the polymerization system after aging with the catalyst and adding the branching agent to the system in 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.

[0084] 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 siloxane-functional branching agent, characterized in that: As shown in formula (I), Wherein, Bd is a butadiene polymerization unit, It is a siloxane group containing two alkyl groups, R1 and R2, wherein R1, R2 and R3 are each independently selected from an alkyl group containing 1 to 3 carbon atoms.

2. The siloxane functionalized branching agent according to claim 1, characterized in that The number average molecular weight of the branching agent is 2000-50000, and the molecular weight distribution is 1.2-2.

0.

3. A method for preparing the siloxane-functional branching agent according to claim 1 or 2, characterized in that: include: Butadiene, solvent and structure regulator are mixed, alkyl lithium is used as initiator, polymerization is carried out, and after the conversion is completed, hydrogen-containing siloxane and hydrosilylation catalyst are added to carry out hydrosilylation reaction.

4. The method according to claim 3, characterized in that The structure regulator is tetrahydrofuran or diethylene glycol dimethyl ether; and the alkyl lithium is n-butyl lithium.

5. The method according to claim 3, characterized in that The hydrosilylation reaction catalyst is a compound or complex of a Group VIII metal, and the amount of the hydrosilylation reaction catalyst added is 0.1 wt% to 20 wt% of the hydrogen-containing siloxane.

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

7. A long-chain branched rare earth butadiene rubber, characterized in that: As shown in formula (II), Wherein, Bd1 is a polybutadiene rubber branch chain; m is the number of branches, selected from a natural number of 20-40; is the main chain, wherein Bd is a butadiene polymerization unit, It is a siloxane group containing two alkyl groups, R1 and R2, wherein R1, R2 and R3 are each independently selected from an alkyl group containing 1 to 3 carbon atoms.

8. The long-chain branched rare earth butadiene rubber according to claim 7, 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 2000-50000.

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

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

11. The method according to claim 10, 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.

12. Use of the long-chain branched rare earth butadiene rubber according to any one of claims 7 or 8 in the preparation of tires.

13. A tire, characterized in that: Comprising the long-chain branched rare earth butadiene rubber as described in any one of claims 7 or 8.

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