Terminal multifunctional solution polymerized styrene-butadiene rubber, composite material of terminal multifunctional solution polymerized styrene-butadiene rubber and white carbon black and preparation method of terminal multifunctional solution polymerized styrene-butadiene rubber and white carbon

Abstract

The invention discloses terminal polyfunctional group modified solution polymerized styrene-butadiene rubber, a composite material of the terminal polyfunctional group modified solution polymerized styrene-butadiene rubber and white carbon black and a preparation method of the terminal polyfunctional group modified solution polymerized styrene-butadiene rubber. The structure of the terminal polyfunctional group modified solution polymerized styrene-butadiene rubber is as shown in the formula (1): # imgabs0 #, and R6 and R7 are the same or different and are independently selected from alkyl or alkoxy; r8 and R9 are the same or different and are independently selected from linear alkyl, cyclic alkyl, phenyl or reactive hydrogen; and m is the number of alkyl groups and is a number from 1 to 3. The functionalized solution polymerized styrene-butadiene rubber is prepared by introducing a polar functional group to a solution polymerized styrene-butadiene rubber chain end in one step through a terminal grafting method, and the introduction of the polar functional group realizes the conversion of molecular polarity from hydrophobicity to hydrophilicity, so that the interfacial compatibility of SSBR and white carbon black is increased, the dispersity of the solution polymerized styrene-butadiene rubber in a filler can be effectively improved, and the stability of the filler is improved. The comprehensive mechanical property of the SSBR vulcanized rubber is improved, and the SSBR vulcanized rubber is applied to the fields of high-performance green tires and new energy vehicle tires.

Description

Technical Field

[0001] The invention belongs to the field of synthetic rubber and relates to a terminal multifunctional solution-polymerized styrene-butadiene rubber suitable for a white carbon black filling system. Background Art

[0002] Solution-polymerized styrene butadiene rubber is a polymer obtained by anionic living polymerization of butadiene and styrene, which was developed in the 1980s. Compared with emulsion-polymerized styrene butadiene rubber (ESBR) prepared by free radicals, solution-polymerized styrene butadiene rubber (SSBR) has a narrower relative molecular weight distribution, a larger relative molecular weight and excellent molecular chain characteristics, so it has relatively low hysteresis loss, excellent wear resistance and groove crack resistance, wet road grip performance, heat resistance and good flexural resistance after long-term exposure to high temperature, etc., and has become a recognized important raw material for the development of green tires.

[0003] At present, the preparation technology of solution-polymerized styrene butadiene rubber has developed to the fourth generation, and has gone through stages such as linear SSBR, carbon black system functionalized SSBR, integrated rubber and white carbon black system functionalized SSBR. At the end of the last century, the technology had developed to the fourth generation abroad and was successfully industrialized. At present, China has completed the industrial test of amine-functionalized SSBR, which is mainly aimed at the carbon black filling system. There is no industrial product under the higher performance and greener white carbon black system.

[0004] Functionalized solution-polymerized styrene-butadiene rubber refers to the introduction of polar groups such as N, Si, O, Sn, and P on its polymer chain. The introduction of these groups realizes the transformation of molecular polarity from hydrophobic to hydrophilic, thereby increasing the interfacial compatibility between SSBR and polar filler silica, which is beneficial to the interaction with the filler, thereby promoting the dispersion of the filler in the rubber matrix; at the same time, due to the interaction between the end and the filler or the interaction itself, the degree of freedom of the chain link between the final cross-linking point and the chain end in the rubber network is reduced, so that it can effectively participate in the elastic recovery of the entire cross-linking network, thereby reducing the energy loss in periodic deformation, improving heat generation and rolling resistance, and improving the comprehensive performance of SSBR vulcanizate. In recent years, the modification research on SSBR has been relatively active, mainly including three methods or their combination forms of functionalization modification of molecular chain ends, grafting modification technology in molecular chains, and functionalized initiators to modify single-functionalized or multi-functionalized SSBR. Currently, the number of literature and patents reporting on the grafting modification of SSBR chains is far less than that of chain end modification, and the content is not exhaustive. The polar groups are expensive and difficult to prepare, and they are even rarer in China.

[0005] There are two main methods for preparing end-functionalized polymers by living anionic polymerization. One is to use a functionalized initiator that can initiate the polymerization of specific monomers. After the polymerization is completed, the functionalized group can be treated or retained. The advantage is that double-end multifunctionalized SSBR can be further prepared, and the synthesis process is simple and the synthesis efficiency is high. The disadvantage is that the preparation of functionalized initiators is difficult and has poor solubility in non-polar solvents such as alkanes. The second is to use functionalized electrophilic reagents to cap the active polymers and introduce a series of functionalized groups at the ends of the polymer chains. Monofunctionalized or multifunctionalized SSBR can be prepared. The process is simple and easy, and the cost is low. It is the preferred solution for preparing multifunctionalized SSBR. The disadvantage is that the functionalized capping reagents need to be screened in the early stage.

[0006] [Keisuke Tokai, Naoichi Kobayashi. Conjugated diene (co)polymer rubber, method for producing (co)polymer rubber, rubber composition, composite and tire [P]. China: CN 1274719C], providing a (co)polymer rubber containing a conjugated diene, or a conjugated diene and an aromatic vinyl compound, which is a conjugated diene (co)polymer rubber having primary amino groups and alkoxysilyl groups bonded to the (co)polymer chain, and also providing a method for producing the same, a rubber composition, a composite and a tire, wherein the conjugated diene (co)polymer rubber has good processability and has a balance of wear resistance, destructive characteristics, low hysteresis loss and anti-skid properties for forming a tread for automobile tires.

[0007] [C. Kens pneumatic tire [P]. China: CN102558631] relates to a pneumatic tire comprising at least one component, wherein the at least one component comprises a rubber composition, wherein the rubber composition comprises: 70-90 phr of styrene-butadiene rubber functionalized with alkoxysilane groups and at least one of primary amine groups and thiol groups; 10-30 phr of at least one other diene-based elastomer; 60-100 phr of precipitated silica; 1-10 phr of polyoctene; 5-25 phr of starch / plasticizer complex; and 10-20 phr of tackifying resin.

[0008] The functionalizing agents involved in the above prior art are as follows:

[0009]

[0010] This structural formula contains two functional groups, N and Si-OR. N is protected by alkyl Si. This part does not react with the active chain of butadiene and is hydrolyzed to obtain NH2 after the polymerization. There are two types of Si-OR groups, either Si connected to three siloxanes or Si connected to two siloxanes. The other is alkyl, aryl and allyl, that is, there are at least two siloxanes. This part reacts with the active chain of butadiene. The mechanism is that one or two siloxanes break and the butadiene active chain is linked to Si. The remaining siloxanes (if any) will not be hydrolyzed during post-treatment condensation. The focus of this technology: After functionalization, the NH2 group is completely retained in the polymer, and the alkoxy group is partially retained and no longer hydrolyzed. The purpose is to highlight the interaction between NH2 and filler, and at the same time combine the retained alkoxy group to bring excellent mechanical properties orientation to the vulcanized rubber (orientation means that functionalization cannot improve all tire performance, but only improves one or several performances without significantly reducing other performances). The Si-protected N-SiOR compound in this technology is difficult to source, has a high preparation cost, has no industrialized products, and is not suitable for large-scale amplification of industrial equipment to prepare functionalized SSBR industrial products.

[0011] CN 110387071 A discloses a branched functionalized solution-polymerized styrene-butadiene rubber / white carbon black composite material. The composite material contains 50-83 parts of solution-polymerized styrene-butadiene rubber, 17-50 parts of white carbon black, and 0-5 parts of auxiliary agents based on 100 parts of the composite material. The chain of the solution-polymerized styrene-butadiene rubber contains α-branched modified siloxane, and the auxiliary agent is selected from antioxidants, etc. However, the technology uses the side chain (i.e., 1,2 structure) of butadiene in the styrene-butadiene polymer for functionalization, which belongs to chain functionalization. Moreover, the functionalizing agent is connected to the unsaturated double bond in the chain through a certain reaction, and the functional group is single.

[0012] CN 108997531 A discloses a multifunctional solution-polymerized styrene-butadiene rubber containing siloxy groups / amino groups at the chain end and in the chain. The multifunctional solution-polymerized styrene-butadiene rubber containing siloxy groups / amino groups at the chain end and in the chain is a terpolymer of butadiene, styrene and a 1,1-diphenylethylene derivative monomer containing siloxy groups / amino groups. The copolymer contains no less than two 1,1-diphenylethylene derivative units containing siloxy groups / amino groups, which can be at the chain end or in the chain. The proportion of each component in the multifunctional solution-polymerized styrene-butadiene rubber containing siloxy groups / amino groups at the chain end and in the chain is based on 100% of the total amount of the terpolymer, wherein the mass percentage of the combined 1,1-diphenylethylene derivative monomer containing siloxy groups / amino groups is in the range of 0.5%-10%, the mass percentage of the combined styrene content is in the range of 5%-55%, and the rest is butadiene. The number average molecular weight of the multifunctional solution-polymerized styrene-butadiene rubber containing siloxy groups / amino groups at the chain end and in the chain is in the range of 5×10 4 -80×104 g / mol; the multifunctional solution-polymerized styrene-butadiene rubber containing siloxy groups / amino groups in the chain end chain is a random structure, a gradient structure or a block structure, and the 1,1-diphenylethylene derivative containing siloxy groups / amino groups in the chain end chain of the multifunctional solution-polymerized styrene-butadiene rubber is evenly distributed or gradiently distributed. However, this technology mainly relies on the reaction of 1,1-diphenylethylene (DPE) with different functionalizing agents to obtain functionalized monomers containing different functional groups, and then adds them to continue the reaction after the reaction of styrene-butadiene to achieve the preparation of solution-polymerized styrene-butadiene rubber containing two functional groups. The preparation process is relatively complicated. In addition, the functionalizing agents in this technology need to be prepared in advance, the cost is high, and it is impossible to prepare on a large scale. The possibility of application in large-scale industrial devices is low, and it is limited to laboratory research. The preparation efficiency of the functionalizing agents used in this technology is too low and the separation is too difficult.

[0013] CN 109880198 A discloses a green tire tread rubber for a passenger car. The rubber material adopts trans-1,4-butadiene-isoprene copolymer rubber TBIR, solution polymerized styrene-butadiene rubber SSBR and cis-butadiene rubber BR as base rubbers. The SSBR / BR / TBIR mixed rubber formula consists of the following components by weight: 40-90 parts of solution polymerized styrene-butadiene rubber SSBR; 5-30 parts of cis-butadiene rubber BR; 5-30 parts of trans-1,4-butadiene-isoprene copolymer rubber TBIR; 0-34 parts of environmentally friendly aromatic oil; 0-105 parts of carbon black; 0-105 parts of white carbon black; 0-5 parts of white carbon black dispersant; 0-15 parts of silane coupling agent; 0.3-5 parts of accelerator; 0.2-3 parts of sulfur; 1-4.5 parts of zinc oxide; 1-9 parts of stearic acid; 0-9 parts of paraffin wax; and 1-3 parts of antioxidant. However, this technology mainly uses homemade trans-butylene rubber and purchased siloxane-functionalized SSBR to mix and vulcanize to prepare vulcanized rubber, and the focus is on the structural regulation and processing technology of homemade trans-butylene rubber. Siloxane-functionalized SSBR is prepared by connecting the end of butadiene to a reagent containing siloxane, and is a monofunctional polymer.

[0014] CN 108084345 A discloses a difunctionalized butadiene styrene polymer, the general formula of which is: (AmPR1) x Si(OR2) y, wherein Am is an aromatic amine group, R1 and R2 are alkyl groups with 1-10 carbon atoms, R3 is an alkyl group or an aryl group with 1-10 carbon atoms, P is a copolymer of butadiene and styrene, x=1-3, y=1-3, z=0-2, and x+y+z=4. However, this technology improves the performance of the vulcanized rubber by the interaction between the introduced functional groups and the fillers (carbon black / white carbon black). The linear structure is the main structure before and after functionalization, and the molecular weight and molecular structure are basically unchanged. Moreover, due to the limitation of the functionalized initiator and the unclear mechanism of the post-processing process, it has only remained in the laboratory stage and has not yet been used in industrial production.

[0015] CN 106008864 A discloses a method for synthesizing end-functionalized rubber with high end-capping efficiency by using negative ion technology. First, in a hydrocarbon solvent, a polar organic compound is used as a regulator and an organic lithium is used as an initiator to initiate a negative ion polymerization reaction of conjugated diene or monovinyl aromatic hydrocarbon to generate an active polymer. Secondly, the active polymer is reacted with a diphenylethylene capping agent to obtain a capped active polymer. Thirdly, the capped active polymer is subjected to an end-capping reaction with a novel siloxane-containing aromatic imine end-capping agent to prepare a functionalized rubber with a silanoxy-amine end group. Finally, the synthesized end-functionalized rubber is mixed with a reinforcing agent, a vulcanizing agent, an accelerator and other compounding agents to prepare a rubber composite material, and the rubber composite material with low rolling resistance, high anti-slip properties and the like is obtained by vulcanization. However, this technology lies in the preparation of advanced butadiene polymer, which is then reacted with a diphenylethylene capping agent to obtain a capping active polymer, and the product is then capped with a functionalizing agent to prepare a functionalized rubber. The linear structure is dominant before and after functionalization, and the molecular weight and molecular structure remain essentially unchanged.

[0016] CN 114867778 A discloses a rubber composition comprising a rubber component, carbon black, and silicon dioxide, wherein the CTAB adsorption specific surface area of ​​the silicon dioxide is 250 m 2 / g or more; the diameter of the aggregate morphology (DCPS) and the primary particle size (DI) of the silica measured by disc centrifugal particle size analysis meet: 700 ≥ D CPS 3 / D I 3≥300; the rubber component comprises at least one selected from natural rubber and polyisoprene rubber, and at least one selected from modified butadiene rubber and modified styrene butadiene rubber; the mass content of the carbon black is 70% or more relative to the total mass content of the carbon black and the silica; and the at least one selected from modified butadiene rubber and modified styrene butadiene rubber is modified by at least one selected from the group consisting of the following hydrocarbyl silane compound represented by formula (IV), the hydrocarbyl silane compound represented by formula (V), the hydrocarbyl silane compound represented by formula (III), the coupling agent represented by formula (VI), the coupling agent represented by formula (VII), the amino lithium represented by formula (VIII), and vinyl pyridine. However, the technology relates to the modifying agent of SSBR on the one hand, and the modification and process description of filler silica on the other hand. Among them, the functionalizing agent also involves two functional groups, N and Si-OR.

[0017] Traditional terminal monofunctionalization methods such as Figure 2 As shown in the figure, it introduces a functional group at the end, but it is usually a single functional group, and the number and type are limited, which ultimately leads to no qualitative improvement in the performance of the functionalized product. Figure 3 As shown, a functionalized initiator is used to prepare SSBR with a functional group on one end, and then a functional group is introduced at the end in an attempt to achieve a double (multi) functionalized SSBR by connecting both ends. However, this method is difficult to prepare the functionalized initiator, has poor solubility and stability, and has a complicated process. It is not suitable for industrial equipment and has poor economic efficiency.

[0018] The performance of the functionalized SSBR in the prior art varies, and its effect on the white carbon black system is not obvious. Therefore, it is necessary to provide a solution-polymerized styrene-butadiene rubber with terminal multi-functional groups modified. Summary of the invention

[0019] The technical problem to be solved by the present invention is to prepare functionalized solution polymerized styrene butadiene rubber by introducing polar functional groups at the chain ends of solution polymerized styrene butadiene rubber in one step through a terminal grafting method. The introduction of polar functional groups realizes the transformation of molecular polarity from hydrophobicity to hydrophilicity, thereby increasing the interfacial compatibility between SSBR and white carbon black, which can effectively improve the dispersibility of solution polymerized styrene butadiene rubber in fillers, improve the comprehensive mechanical properties of SSBR vulcanizates, and be applied to the fields of high-performance green tires and new energy vehicle tires.

[0020] To achieve the above object, the present invention provides a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber.

[0021] The structure of the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber is shown in the following formula (1):

[0022]

[0023] Among them, R6 and R7 are the same or different, and are independently selected from hydroxyl, alkyl or alkoxy; R8 and R9 are the same or different, and are independently selected from benzene ring, active hydrogen, hydroxyl or alkoxy; m is the number of alkyl groups, which is 1-3.

[0024] In the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention, preferably, R6 and R7 are the same or different, and are independently selected from one of hydroxyl, CH3, CH2CH3, CH2CH2CH3, OCH3, OCH2CH3, and OCH2CH2CH3; R8 and R9 are the same or different, and are independently selected from one of phenyl, active hydrogen, hydroxyl, OCH3, or OCH2CH3; and m is a number of 2-3.

[0025] The terminal multi-functional group modified solution polymerized styrene butadiene rubber of the present invention is a solution polymerized styrene and butadiene random copolymer, and the styrene and butadiene two monomer units are randomly distributed on the polymer main chain; the molecular weight of the copolymer is 5000-500000, the styrene content is 10wt%-40wt%, the vinyl content of the butadiene unit is 20wt%-70wt%, and the content of functional groups in the polymer is 0.1wt%-5wt% of the weight of the solution polymerized styrene butadiene rubber.

[0026] The terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber of the present invention preferably has a molecular weight of the copolymer of 100,000-200,000.

[0027] The invention also provides a composite material formed by the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber and white carbon black.

[0028] The present invention further provides a method for preparing a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, the preparation method comprising the following steps:

[0029] (1) adding a solvent, styrene, butadiene, and an activator to a reactor in sequence, raising the temperature, adding an initiator, and initiating a polymerization reaction to obtain a random SSBR segment;

[0030] (2) adding a functionalized end-capping agent to react to obtain a solution-polymerized styrene-butadiene rubber modified with multiple functional groups at the end;

[0031] Wherein, the structure of the functionalized end-capping agent is shown in the following formula (2):

[0032]

[0033] Among them, R5 is an alkyl group; R6 and R7 are the same or different, and are independently selected from hydroxyl, alkyl or alkoxy; R8 and R9 are the same or different, and are independently selected from phenyl, active hydrogen, hydroxyl or alkoxy; m is the number of alkyl groups, which is 1-3.

[0034] The preparation method of the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention, R6, R7 are the same or different, and are independently selected from one of hydroxyl, CH3, CH2CH3, CH2CH2CH3, OCH3, OCH2CH3, OCH2CH2CH3; R8, R9 are the same or different, and are independently selected from one of phenyl, active hydrogen, hydroxyl, OCH3 or OCH2CH3; m is a number of 2-3.

[0035] The method for preparing the terminal multi-functional group modified solution polystyrene-butadiene rubber of the present invention further comprises a step (2-1) between step (1) and step (2), wherein the step (2-1) is performed before step (2), and comprises: adding butadiene and continuing the reaction to obtain the SSBR having a polybutadiene chain segment at the end.

[0036] In the method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention, the reaction temperature of the step (2-1) is 40° C.-100° C., the pressure is 0.1 MPa-0.60 MPa, and the reaction time is 10 min-30 min.

[0037] The method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention is characterized in that the polymerization reaction is carried out in an oxygen-free, water-free and inert gas environment, and belongs to solution polymerization.

[0038] The method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention comprises the solvent comprising at least one of aromatic hydrocarbons, aliphatic alkanes and cycloalkanes.

[0039] Preferably, the aromatic hydrocarbon includes at least one of benzene, toluene and ethylbenzene.

[0040] Preferably, the aliphatic alkane includes at least one of pentane, hexane, heptane and octane.

[0041] Preferably, the cycloalkane includes at least one of cyclopentane and cyclohexane.

[0042] The preparation method of the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention comprises the following steps: the amount of the solvent added is 300wt%-1000wt% of the total weight of styrene and butadiene monomers.

[0043] The method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention comprises the following steps: the initiator is at least one of n-butyl lithium, sec-butyl lithium, tert-butyl lithium and hexyl lithium.

[0044] In the method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention, the amount of the initiator used is 0.2-3 mmol per 100 grams of total monomers, and n-butyl lithium is preferred.

[0045] The preparation method of the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention comprises the following steps: the activator is a nitrogen-, oxygen- and other heterocyclic organic compound with a certain polarity, and is selected from at least one of tetrahydrofuran, ethyl tetrahydrofurfuryl ether, tetramethyl divinyl diamine, tetrahydrofuran methanol and diethylene glycol dimethyl ether (2G).

[0046] The dosage of initiator is determined by the monomer content and the molecular weight of the SSBR chain segment, and the dosage of activator is determined by the type of activator (polarity) and the content of side groups. It mainly adjusts the reactivity ratio of the two monomers in the polymerization reaction and the microstructure of butadiene to ensure that butadiene and styrene are random copolymers.

[0047] In the method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention, the added amount of the activator is 20wt%-2000wt% of the initiator.

[0048] The activator can adjust the vinyl content of butadiene, adjust the reactivity ratio of styrene and butadiene, and make the two copolymerize randomly, and at the same time can make the alkyl lithium initiator produce polarization or solvation effect, reduce its association degree, and increase the initiation reaction speed of the initiator such as n-butyl lithium. The present invention does not particularly limit the source of the activator, which can be commercially available or prepared by conventional methods in the art.

[0049] The method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention comprises the following steps: in step (1), the polymerization reaction temperature is 40-100° C., the pressure is 0.1 MPa-0.60 MPa, and the time is 30 min-90 min.

[0050] In the method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention, in step (2), the reaction temperature is 40° C.-100° C., and the reaction time is 10 min-30 min.

[0051] In the method for preparing the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber of the present invention, the functionalized end-capping agent can be added all at once or divided into two or three times.

[0052] In one embodiment, after the preparation of the terminal multifunctional group modified solution polymerized styrene butadiene rubber is completed, an antioxidant may be added to improve its aging resistance. Specifically, the following method may be used: the polymer solution obtained after the preparation of the terminal multifunctional group modified solution polymerized styrene butadiene rubber is transferred to a chemical treatment kettle after the polymerization is completed, an antioxidant is added, and then the polymer is separated from the solution to obtain the modified double-end multifunctional solution polymerized styrene butadiene rubber. The antioxidant is, for example but not limited to, one or more of 1520L, 1076, 1010, 264, TNPP, and triisopropanolamine for compounding, and the amount of the antioxidant added is 0.5wt%-5wt%, preferably 0.5wt%-2wt%. The separation of the polymer from the solution may be carried out by a conventional steam stripping condensation method, or by a devolatilization screw extruder.

[0053] In detail, the preparation method of the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber of the present invention can be carried out by the following two methods:

[0054] Method 1: In a polymerization kettle that is evacuated and replaced with argon, add solvent, styrene, butadiene, and activator in sequence, start hot water circulation, and when the polymerization system reaches a predetermined temperature, stop the hot water circulation, add initiator, initiate polymerization for a certain period of time, and form SSBR random segments. The reaction temperature is 40°C-100°C, the reaction pressure is 0.1MPa-0.60MPa, and the reaction time is 30min-90min. At this time, the monomer conversion rate reaches 100%. The amount of initiator is determined by the monomer content and the molecular weight of the SSBR segment, and the amount of activator is determined by the type of activator (polarity) and the side group content. It mainly adjusts the reactivity ratio of the two monomers in the polymerization reaction and the microstructure of butadiene to ensure that butadiene and styrene are random copolymers. The combined styrene content in the SSBR segment is 10wt%-40wt%, and the vinyl content of the butadiene unit is 20wt%-70wt%. Then, a functionalized end-capping agent is added, and the reaction temperature is maintained at 40° C.-100° C. for 10 min-30 min to form a multifunctionalized SSBR.

[0055] The Si-OR involved in the present invention has at least one siloxane, and the remaining two can be siloxane, or alkyl, aryl and allyl. The active chain of styrene preferentially reacts with Si-OR, and the mechanism is that according to the different substituent groups and dosages, one or more siloxanes are broken, and the active chain of styrene is linked to Si to form a haploid or polyploid. At this time, the molecular weight of the polymer increases and the molecular chain becomes longer. After the reaction is completed, the residual siloxane in the coagulation post-treatment process will be partially hydrolyzed to generate silanol groups. The functionalized polymer may contain functional groups such as Si-OR and Si-OH, and the various functional groups and fillers can play a synergistic role with each other, thereby giving the vulcanized rubber a relatively complete and excellent mechanical performance orientation. The functionalized compound involved in the present invention can not only realize the preparation of multifunctionalized SSBR through a one-step method with excellent performance, but also has an existing industrial product with low cost, and is suitable for industrial amplification to prepare high-performance green tire treads.

[0056] Method 2: The difference from method 1 is that after the random SSBR segments are formed in method 1, a small amount of butadiene is added to the polymerization kettle to continue the reaction for a period of time to first obtain SSBR with polybutadiene segments at the end. The polymerization reaction temperature in this stage is 40℃-100℃, the reaction pressure is 0.1MPa-0.60MPa, and the reaction time is 10min-30min. Then, a functionalized end-capping agent is added, the reaction temperature is maintained at 40℃-100℃, and the reaction is carried out for 10min-30min to obtain a multifunctional SSBR.

[0057] The idea of ​​the present invention is to use a functionalized end-capping agent containing multiple functional groups to prepare a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber by using an end-capping method, and the method is simple and easy to implement. After styrene and butadiene are initiated by an initiator, when the conversion rate reaches 95%, a multi-functional end-capping agent is used to react and cap the end to prepare a terminal bifunctional group-modified solution-polymerized styrene-butadiene rubber.

[0058] The method of the present invention is simple and easy to implement, does not require the cumbersome process of using a functionalized initiator to functionalize both ends to achieve multifunctionalization, has mild conditions, can be adapted to existing anionic solution polymerization devices, and can also be satisfied with newly built anionic solution polymerization devices. The vulcanized rubber prepared by using the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber of the present invention can improve the wear resistance and wet skid resistance of the solution-polymerized styrene-butadiene rubber and reduce rolling resistance.

[0059] The present invention is different from the traditional multifunctionalization concept (such as Figure 2 and 3 As shown in FIG. 1 and FIG. 2 , the concept of the present invention is different from that of the implementation method. Figure 4As shown, multifunctional solution-polymerized styrene-butadiene rubber is prepared by introducing a developed functionalizing agent containing multiple functional groups at the end of the polymer. The process is simple and easy, saves cost and time, and is conducive to intermittent or continuous production in industrial equipment.

[0060] After the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber of the present invention introduces a functionalized end-capping group containing a multi-functional group at the terminal, the types and quantities of the functional groups are qualitatively improved, and the polarity of the solution-polymerized styrene-butadiene rubber can be truly enhanced, thereby enhancing the interaction between the solution-polymerized styrene-butadiene rubber and the filler, and further effectively promoting the dispersion of the filler in the solution-polymerized styrene-butadiene rubber. The high-performance tire developed using the composite material formed by the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber and the filler of the present invention has the characteristics of low rolling resistance, low fuel consumption, excellent handling stability, shorter braking distance, better wear resistance, multiple refurbishment, etc. Compared with traditional tires, it highlights the advantages of environmental protection, energy saving, safety, new technology, new materials, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Schematic diagram of traditional unfunctionalized SSBR.

[0062] Figure 2 Schematic diagram of traditional terminal monofunctionalized SSBR.

[0063] Figure 3 Schematic diagram of the traditional difunctionalized SSBR using functionalized initiator.

[0064] Figure 4 It is a schematic diagram of the solution-polymerized styrene-butadiene rubber modified with terminal multi-functional groups according to the present invention.

[0065] Figure 5 The terminal multifunctional group-modified solution-polymerized styrene-butadiene rubber of Example 1 1 H-NMR spectrum. DETAILED DESCRIPTION

[0066] The following examples are selected to further illustrate the method of the present invention, but should not be limited thereto in practical applications. This example is used to illustrate the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber and its preparation method and vulcanized rubber provided by the present invention.

[0067] The polymer characterization and rubber performance evaluation in the examples were performed using the following instruments: US Varian INOVA400 NMR nuclear magnetic resonance 1H-NMR was used to qualitatively and quantitatively analyze the composition sequence distribution and microstructure of the copolymers. TDA302 gel permeation chromatography (GPC) produced by Viscotek, USA, was used to analyze the molecular weight and molecular weight distribution of the copolymers. The mechanical properties were tested using a 4465 universal material testing machine produced by NSTRON, USA. The dynamic mechanical properties were tested using a DMAQ800 / RSA3 dynamic thermomechanical analyzer from USA.

[0068] (1) Mechanical properties test: tensile strength and elongation at break were tested in accordance with GB / T528-2009, and tear strength test was tested in accordance with GB / T529-2008.

[0069] (2) Shore A hardness test: The test shall be conducted in accordance with the method specified in GB / T23651-2009.

[0070] (3) Dynamic mechanical properties test: The dynamic mechanical properties test was performed using the American DMAQ800 / RSA3 dynamic thermomechanical analyzer.

[0071] Example 1

[0072] In a 10L polymerizer with a jacket, argon was passed through the system to replace it three times. 5109g of hexane, 200g of styrene, 600g of butadiene, and 0.62g of ethyl tetrahydrofurfuryl ether were added to the polymerizer, and the temperature was raised to 50°C. 5.3mmol of n-butyl lithium was added, and the temperature was naturally raised to 50°C. After 2 hours of polymerization, the conversion rate reached 100%, and a linear polymer with a number average molecular weight of 150,000 and a molecular weight distribution of 1.2 was obtained; then the temperature was raised to 60°C, and 106mmol of functionalized end-capping reagent (m=2, R6=R7=OCH2CH3, R8=R9=OCH3) was added to the polymerizer at one time. After continuing the reaction for 0.5 hours, the reaction was terminated to obtain a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, which was recorded as J1. Antioxidant was added, the material was discharged, and the rubber solution was wet-coagulated, dried, and set aside.

[0073] Comparative Example 1

[0074] The method of Example 1 is followed, except that no functionalized end-capping agent is added, and finally unfunctionalized styrene-butadiene rubber is obtained, which is recorded as D1.

[0075] Example 2

[0076] The method of Example 1 is followed, except that "adding in two portions" is used instead of "adding all at once" to obtain a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, which is denoted as J2.

[0077] Example 3

[0078] The method of Example 1 is followed, except that "adding in three times" is used instead of "adding all at once" to obtain a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, which is recorded as J3.

[0079] Example 4

[0080] The method of Example 1 is followed, except that "adding 7.95 mmol of n-butyl lithium" and "obtaining a number average molecular weight of 100,000" replace "adding 5.3 mmol of n-butyl lithium" and "obtaining a number average molecular weight of 150,000" to obtain a terminal multi-functional group modified solution-polymerized styrene-butadiene rubber, which is recorded as J4.

[0081] Example 5

[0082] The method of Example 1 is followed, except that "adding 3.975 mmol of n-butyl lithium" and "obtaining a number average molecular weight of 200,000" replace "adding 5.3 mmol of n-butyl lithium" and "obtaining a number average molecular weight of 150,000", to obtain a terminal multi-functional group modified solution polymerized butadiene styrene rubber, recorded as J5.

[0083] Example 6

[0084] The method of Example 1 was followed, except that “80 g styrene and 720 g butadiene” were used instead of “200 g styrene and 600 g butadiene”, to obtain a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, which was recorded as J6.

[0085] Example 7

[0086] The method of Example 1 was followed, except that "0.28 g of ethyl tetrahydrofurfuryl ether" was used instead of "0.62 g of ethyl tetrahydrofurfuryl ether", to obtain a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, which was recorded as J7.

[0087] Example 8

[0088] The method of Example 1 was followed, except that “the conversion rate reached 100%, followed by adding 60 g of butadiene and continuing the reaction for 15 minutes” was replaced with “the conversion rate reached 100%” to obtain a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, recorded as J8.

[0089] Example 9

[0090] The method of Example 1 was followed, except that "53 mmol of the functionalized end-capping agent was added all at once" was replaced with "106 mmol of the functionalized end-capping agent was added all at once" to obtain a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, denoted as J9.

[0091] Example 10

[0092] The method of Example 1 is followed, except that "m=2, R6=R7=OCH2CH3, R8=R9=phenyl" is used to replace "m=2, R6=R7=OCH2CH3, R8=R9=OCH3" to obtain a terminal multi-functional group modified solution-polymerized styrene-butadiene rubber, which is recorded as J10.

[0093] Embodiment 11

[0094] The method of Example 1 is followed, except that "m=2, R6=R7=OCH2CH3, R8=R9=OCH3" is replaced by "m=3, R6=R7=OCH2CH3, R8=R9=phenyl" to obtain a terminal multi-functional group modified solution-polymerized styrene-butadiene rubber, which is recorded as J11.

[0095] Example 12

[0096] The method of Example 1 is followed, except that "m=2, R6=R7=OCH2CH3, R8=R9=OCH2CH3" is used to replace "m=2, R6=R7=OCH2CH3, R8=R9=OCH3" to obtain a terminal multi-functional group modified solution-polymerized styrene-butadiene rubber, which is recorded as J12.

[0097] Embodiment 13

[0098] The method of Example 1 is followed, except that "m=2, R6=R7=OCH2CH3, R8=R9=OCH3" is used to replace "m=2, R6=R7=OH, R8=H, R9=OCH3" to obtain a terminal multi-functional group modified solution-polymerized styrene-butadiene rubber, which is recorded as J13.

[0099] Preparation Example 1

[0100] The terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber obtained in Examples 1-13 and the styrene-butadiene rubber obtained in Comparative Example 1 were mixed and vulcanized to obtain a vulcanized rubber, and the preparation process thereof is as follows:

[0101] 100 parts by weight of terminal multifunctional group-modified solution-polymerized styrene-butadiene rubber or styrene-butadiene rubber, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of vulcanization accelerator DM, 2 parts by weight of vulcanization accelerator D0.6, 1.5 parts by weight of antioxidant RD, 6 parts by weight of Si-69, 70 parts by weight of white carbon black SiO2, 5 parts of carbon black N330 and 2 parts by weight of sulfur are added to an open mill, and then mixed in an internal mixer for 15 minutes according to a certain sequence and process, and then the obtained mixed rubber is vulcanized for 20 minutes at a temperature of 160°C and a pressure of 15 MPa using a flat vulcanizer to obtain vulcanized rubbers S1-S13 and C1.

[0102] The vulcanized rubbers S1-S13 were used for performance evaluation, and the results are shown in Table 1.

[0103] Table 1 Vulcanized rubber performance test results

[0104]

[0105]

[0106] It can be seen from the results of the embodiments that the SSBR modified with terminal multi-functional groups obtained after adding the functionalized end-capping agent has improved dynamic mechanical properties and wear to varying degrees compared with the unmodified SSBR on the basis of improved mechanical properties. It can be seen from the comparison results of different embodiments that wear mainly depends on the number of chemical bonds formed by the alkoxy group and the silica, and if there is a synergistic effect of the phosphorus oxy group at the same end, the wear resistance will be very excellent. The reduction of hysteresis loss mainly depends on the hydrogen bonding effect formed by the phosphorus oxy group and the hydroxyl group on the surface of silica and the synergistic effect with the alkoxy group, and the effect of the phosphorus oxy group occupies a dominant position. The synergistic effect can be understood as: the phosphorus oxy group forms a hydrogen bond with the surface of silica, acts as a catalyst, and adsorbs the polymer end to the surface of silica. The phosphorus oxy group can promote the interaction with the acidic functional groups on the surface of the filler, thereby providing a dispersion and reinforcement effect of the filler. The adjacent alkoxysilanes react with the silanol condensation reaction on the surface of silica to form chemical bonds to jointly promote the improvement of wear resistance and the reduction of hysteresis loss.

[0107] In summary, it can be seen from the test results that the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber prepared by the method of the present invention has significantly improved performance as a rubber-based rubber compared to unfunctionalized SSBR, and has very excellent mechanical properties, high anti-skid properties and low rolling resistance. Moreover, the performance orientations of molecular structure SSBR are different. It is a new type of green tread rubber with excellent performance and has great industrial application prospects.

[0108] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A solution-polymerized styrene-butadiene rubber with terminal multi-functional groups modified, characterized in that: The structure of the terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber is shown in the following formula (1): Among them, R6 and R7 are the same or different, and are independently selected from hydroxyl, alkyl or alkoxy; R8 and R9 are the same or different, and are independently selected from phenyl, active hydrogen, hydroxyl or alkoxy; m is the number of alkyl groups, which is 1-3.

2. The terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber according to claim 1, characterized in that: R6 and R7 are the same or different, and are each independently selected from one of hydroxyl, CH3, CH2CH3, CH2CH2CH3, OCH3, OCH2CH3, and OCH2CH2CH3; R8 and R9 are the same or different, and are each independently selected from one of phenyl, active hydrogen, hydroxyl, OCH3, and OCH2CH3; m is a number of 2-3.

3. The terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber according to claim 1, characterized in that: The solution polymerized styrene butadiene rubber is a solution polymerized styrene and butadiene random copolymer, wherein the styrene and butadiene monomer units are randomly distributed on the polymer main chain; the molecular weight of the copolymer is 5000-500000, the styrene content is 10wt%-40wt%, the vinyl content of the butadiene unit is 20wt%-70wt%, and the content of functional groups in the polymer is 0.1wt%-5wt% of the weight of the solution polymerized styrene butadiene rubber.

4. The terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber according to claim 1, characterized in that: The molecular weight of the copolymer is 100,000-200,000.

5. A composite material formed by the terminal multi-functional group modified solution-polymerized styrene-butadiene rubber according to any one of claims 1 to 4 and white carbon black.

6. A method for preparing a terminal multi-functional group-modified solution-polymerized styrene-butadiene rubber, characterized in that: The following steps are involved: (1) adding a solvent, styrene, butadiene, and an activator to a reactor in sequence, raising the temperature, adding an initiator, and initiating a polymerization reaction to obtain a random SSBR segment; (2) adding a functionalized end-capping agent to react to obtain a solution-polymerized styrene-butadiene rubber modified with multiple functional groups at the end; Wherein, the structure of the functionalized end-capping agent is shown in the following formula (2): Among them, R5 is an alkyl group; R6 and R7 are the same or different, and are independently selected from hydroxyl, alkyl or alkoxy; R8 and R9 are the same or different, and are independently selected from phenyl, active hydrogen, hydroxyl or alkoxy; m is the number of alkyl groups, which is 1-3.

7. The preparation method according to claim 6, characterized in that: R6 and R7 are the same or different, and are each independently selected from one of hydroxyl, CH3, CH2CH3, CH2CH2CH3, OCH3, OCH2CH3, and OCH2CH2CH3; R8 and R9 are the same or different, and are each independently selected from one of phenyl, active hydrogen, hydroxyl, OCH3, and OCH2CH3; m is a number of 2-3.

8. The preparation method according to claim 6, characterized in that: A step (2-1) is included between step (1) and step (2), and the step (2-1) is performed before step (2), comprising: adding butadiene and continuing the reaction to obtain SSBR with a polybutadiene chain segment at the end.

9. The preparation method according to claim 8, characterized in that: The reaction temperature of step (2-1) is 40°C-100°C, the pressure is 0.1MPa-0.60MPa, and the time is 10min-30min.

10. The preparation method according to claim 6, characterized in that: The polymerization reaction is carried out in an oxygen-free, water-free, inert gas environment.

11. The preparation method according to claim 6, characterized in that: The solvent includes at least one of aromatic hydrocarbons, aliphatic alkanes, and cycloalkanes; The aromatic hydrocarbons include at least one of benzene, toluene and ethylbenzene; The aliphatic alkane includes at least one of pentane, hexane, heptane and octane; The cycloalkane includes at least one of cyclopentane and cyclohexane; The amount of the solvent added is 300wt%-1000wt% of the total weight of styrene and butadiene monomers.

12. The preparation method according to claim 6, characterized in that: The initiator is at least one of n-butyl lithium, sec-butyl lithium, tert-butyl lithium and hexyl lithium; The initiator is used in an amount of 0.2-3 mmol per 100 g of total monomers.

13. The preparation method according to claim 6, characterized in that: The activator is selected from at least one of tetrahydrofuran, ethyl tetrahydrofurfuryl ether, tetramethyl divinyl diamine, tetrahydrofuran methanol, and diethylene glycol dimethyl ether; The added amount of the activator is 20wt%-2000wt% of the initiator.

14. The preparation method according to claim 6, characterized in that: In step (1), the polymerization reaction is carried out at a temperature of 40°C-100°C, a pressure of 0.1MPa-0.60MPa, and a time of 30min-90min; In step (2), the reaction temperature is 40°C-100°C and the reaction time is 10min-30min.

15. The preparation method according to claim 6, characterized in that: The functional end-capping reagent is added all at once or divided into two or three times.

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