Continuous polymerization method for preparing rare earth butadiene rubber

Abstract

The invention discloses a continuous polymerization method for preparing rare earth butadiene rubber, and belongs to the technical field of high polymer material synthesis. The polymerization method comprises the following steps: preparation of a neodymium complex catalyst system, preparation of a long-chain alkane modified polysilane dispersant and continuous polymerization of rare earth butadiene rubber. The preparation method comprises the following steps: firstly, preparing an indole ligand by using reactive hydrogen on indole, replacing the indole ligand with neodymium chloride to obtain a neodymium complex catalyst, and synergistically constructing a high-stability cis-oriented bimetallic active center with a cocatalyst and a stabilizer, thereby breaking through 99% of the cis-structure limit. The preparation of the long-chain alkane modified polysilane dispersing agent is realized through hydrosilylation reaction, a continuous solvent polymerization process is combined, the chain entanglement degree is remarkably reduced, the system viscosity is reduced compared with that of a traditional process, a catalyst is added in a gradient manner, a high activity center is ensured in the whole polymerization process, the monomer is ensured to be inserted in an ultrahigh stereoregularity manner, and the preparation method has the advantages that the preparation process is simple, and the preparation cost is low. And ultrahigh cis-polymerization of butadiene is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer material synthesis, and particularly relates to a continuous polymerization method for preparing rare earth butadiene rubber. BACKGROUND

[0002] The rare earth butadiene rubber is a key material for manufacturing high-performance tires and high-end products due to its excellent wear resistance, fatigue resistance and low rolling resistance. The core index of its performance lies in the content of cis-1,4 structure in the molecular chain, and the ultra-high cis structure can significantly improve the physical and mechanical properties and dynamic mechanical properties of the rubber.

[0003] At present, a neodymium catalyst system is generally used for continuous solution polymerization in the industry. However, there are two core problems in the traditional method: Firstly, it is difficult to break through the limit of 99% cis structure under the traditional catalyst system and polymerization process, and the content of cis structure is usually maintained at 96%-98%. The reason is that the active center is prone to isomerization or deactivation during the polymerization process, resulting in insufficient control precision of the microstructure.

[0004] Secondly, as the polymerization reaction proceeds, the viscosity of the system rapidly rises, which leads to great difficulty in mixing, heat dissipation and mass transfer of the materials in the reactor, and easily causes local overheating, uneven catalyst concentration, broad molecular weight distribution, and even gel, thereby seriously affecting the uniformity and stability of the product quality. Therefore, it is urgent to develop a continuous polymerization technology which takes into account the ultra-high cis structure and efficient dispersion. SUMMARY

[0005] The present application relates to the technical field of high polymer material synthesis, and particularly relates to a continuous polymerization method for preparing rare earth butadiene rubber.

[0006] In order to achieve the above-mentioned purpose, the technical scheme is as follows: A continuous polymerization method for preparing rare earth butadiene rubber, comprising the following steps: S1, preparation of a neodymium complex catalyst S101, in a basic dimethyl sulfoxide solvent, 10% of indole based on the total mass of the system is added, stirred and dissolved, 11-13% of chloroethyl dimethylamine hydrochloride based on the total mass of the system is gradually added under ice water bath, and the reaction is carried out for 4-5h. Then, three times the volume of ice water is added, and the organic phase is extracted with ethyl acetate three times, washed with saturated sodium chloride solution, filtered, rotary evaporated under reduced pressure, and chromatographed with petroleum ether and ethyl acetate at a ratio of 1:1 to obtain 1-(N,N-dimethylaminoethyl) indole; Indole is dissolved in dimethyl sulfoxide solvent, under alkaline conditions, the active hydrogen (-NH-) on the indole pyrrole ring is deprotonated by the base in the system to generate indole anion with strong nucleophilicity; ice water bath low temperature conditions can inhibit side reactions, such as polyalkylation, indole ring addition, etc., but also can control the reaction rate, at this time the nucleophilic indole anion attacks the α-methylene carbon connected with the chlorine atom in the chloroethyl dimethylamine hydrochloride through nucleophilic substitution reaction, the chlorine atom is a good leaving group, forming N-(2-chloroethyl)-indole intermediate, and then removing Cl - , generating 1-(N,N-dimethylaminoethyl) indole, after 4-5h, add three times the volume of ice water, the main purpose is to quench the remaining base to terminate the reaction, while also reducing the solubility of the product in water, followed by ethyl acetate extraction to realize phase transfer using the hydrophobicity of the product, saturated sodium chloride washing to remove organic phase residual water and impurities, vacuum rotary evaporation to obtain the crude product, finally through petroleum ether / ethyl acetate column chromatography to realize purification, to obtain pure 1-(N,N-dimethylaminoethyl) indole;

[0007] S102, dissolve 1-(N,N-dimethylaminoethyl) indole in acetic acid, add 8-10% of the total mass of the system tetrahydro-pyrrole, ice water bath stirring, add 30wt% formaldehyde solution, reaction 3-4h, add three times the volume of sodium hydroxide solution, dichloromethane extraction, saturated sodium chloride solution washing, filtration, vacuum rotary evaporation, methanol and dichloromethane 1:1 chromatography, the chromatography and equimolar chlorinated neodymium are placed in n-hexane, stirring reaction 3h, vacuum, n-hexane and toluene mixture extraction, low temperature standing 3 days, to obtain neodymium complex catalyst; Mannich reaction refers to the three-component condensation reaction between a compound containing α-active hydrogen, formaldehyde and an amine, under acidic conditions of acetic acid, formaldehyde is first protonated to generate hydroxymethyl cation, which reacts with the secondary amine in tetrahydro-pyrrole to form imine intermediate, indole 3 contains active hydrogen, which acts as a nucleophile to attack the imine intermediate to generate 1-(N,N-dimethylaminoethyl)-3-(tetrahydro-pyrrole methyl) indole ligand, ice water bath can inhibit the self-polymerization of formaldehyde and the excessive alkylation of indole, followed by neutralization of acetic acid with sodium hydroxide to free the ligand, quenching the reaction, dichloromethane extraction, saturated sodium chloride washing to remove impurities, vacuum rotary evaporation to obtain pure ligand;

[0008] When the ligand reacts with equimolar NdCl3 in n-hexane, the rare earth metal atom center forms a σ bond with the C atom at the 2-position of indole, and the 1-position dimethylamino nitrogen and the 3-position tetrahydro-pyrrole methyl nitrogen form a tridentate chelation with Nd 3+ , and Cl -As a monodentate ligand to supplement the coordination number, the Cl atom and the steric hindrance of tetrahydrofuran dimethylamine are large, the coordination number of the central neodymium atom is 5, forming two five-membered ring neodymium positive ion active centers, and the complex is slowly crystallized by extracting and low-temperature standing in n-hexane-toluene mixed solution, and finally the stable neodymium complex catalyst is obtained;

[0009] S2, Preparation of long-chain alkane modified polysilane dispersant S201, Sodium bicarbonate and 1, 3-divinyl tetramethyl disiloxane are mixed uniformly at a mass ratio of 1:2.5, heated to 50℃, and chloroplatinic acid-isopropyl alcohol-toluene mixed solution is slowly added into the system, 60℃ for 1h, heated to 65-70℃ for 2h, low-temperature standing for 10h, rotary evaporation under reduced pressure, and dilution to obtain platinum catalyst; Isopropyl alcohol changes the platinum in chloroplatinic acid to +2 valence, and the generated hydrochloric acid is neutralized by sodium bicarbonate to prevent the reaction of hydrochloric acid with divalent platinum ions, and isopropyl alcohol continues to reduce Pt 2+ to 0 valence, and the vinyl double bond in the 1, 3-divinyl tetramethyl disiloxane molecule is coordinated with Pt empty orbit by π electron, and the active center of platinum catalyst is 0 valence platinum: H2PtCl6+2(CH3)2CHOH→PtCl2+2(CH3)2CO+4HCl+2H2O

[0010] S202, In the pretreated hydrogen-containing silicone oil, 1% of the inhibitor solution based on the total mass of the system is added, stirred, and nitrogen is passed for 10min, and the platinum catalyst is mixed uniformly with 1-octadecene at a mass ratio of 1:300, and slowly added into the hydrogen-containing silicone oil, and the reaction is continued for 2.5h, and 5% of neutral alumina based on the total mass of the system is stirred for 30min, and then filtered, and the filtrate is rotary evaporated under reduced pressure for 2h, and anhydrous sodium sulfate is added and stood, and filtered to obtain long-chain alkane modified polysilane dispersant; The compound containing Si-H bond reacts with long-chain α-olefin under the action of platinum catalyst to obtain long-chain alkane modified polysilane. The inhibitor inhibits the premature side reaction of platinum catalyst with 1-octadecene at room temperature, nitrogen is passed to exclude oxygen to prevent 0 valence platinum from being oxidized and deactivated, after heating to 55℃, 0 valence platinum first oxidizes and adds to Si-H bond in hydrogen-containing silicone oil to form Pt-H / Pt-Si intermediate, then coordinates with C=C bond of 1-octadecene, migrates and inserts to form C-Si bond, and finally reduces and eliminates to regenerate Pt, and the subsequent neutral alumina adsorbs residual Pt, rotary evaporates under reduced pressure to remove low-boiling substances, and anhydrous sulfuric acid removes trace water, and finally long-chain alkyl modified polysilane is obtained, and the long-chain alkyl group can anchor polybutadiene and siloxane main chain to form a solvation layer, and finally the purpose of dispersion and anti-sticking is achieved;

[0011] S3, continuous polymerization process of rare earth butadiene rubber Neodymium complex catalyst, ethyl chloro aluminum and organic boron reagent are mixed uniformly according to the ratio of Nd:Al:B=1:5-25:2, pre-activated at 30-40℃ for 30-60min, 2 / 3 volume of activated catalyst is added into polymerization kettle 1 with dehydrated and deoxidized butadiene-cyclohexane solution, continuously, 50-70℃ reaction for 1-2h, transfer into polymerization kettle 2, start stirring, then add 1 / 3 volume of activated catalyst, 0.1-0.5% of long-chain alkane modified polysilane dispersant in total system, 70-90℃ for 1.5-3h, add 5-10wt% of ethanol and 0.1-0.2wt% of 2,6-di-tert-butyl-p-cresol aqueous solution to terminate the reaction, the glue solution is condensed by hot water and steam, dehydrated and dried, briquetted, and rare earth butadiene rubber is obtained; Ethyl chloro aluminum as an alkyl reagent, organic boron reagent stabilizes the active center, mixed in proportion to form active centers with cis orientation ability, the activated catalyst is first reacted with butadiene-cyclohexane solution at 50-70℃ for 1-2h to complete the initial cis polymerization and generate primary polybutadiene chains. At this time, the solution viscosity in the kettle is low, the conversion rate is about 50%, and a small amount of catalyst loses activity. After transferring into polymerization kettle 2, the remaining activated catalyst is added to improve the total conversion rate, and long-chain alkane modified polysilane dispersant is also added. The long-chain alkyl group anchors the polybutadiene chain and the siloxane backbone to form a solvation layer, effectively preventing chain entanglement and reducing viscosity. At the same time, it also effectively reduces product wall sticking. Continue to react at 70-90℃ for 1.5-3h. As the reaction proceeds, the system becomes more and more viscous, and stirring ensures uniform mixing of the materials in the kettle. Continue to react, finally add ethanol to terminate the active center and stop the polymerization. 2,6-di-tert-butyl-p-cresol inhibits rubber aging. After condensation and drying, rare earth butadiene rubber with high cis-1,4 structure content is obtained; AlEt2Cl as a strong alkylating agent, replaces the Cl ligand on the neodymium complex, the steric hindrance of ethyl is slightly larger than that of chlorine atom, so two ethyl groups form coordination bonds around the neodymium atom, and two ethyl groups also coordinate with aluminum to form neodymium-aluminum double active centers; In the initial stage of the polymerization reaction, the two double bonds of butadiene are connected with neodymium and aluminum to form a butenyl structure. At this time, the butenyl group, neodymium, ethyl group and aluminum form a ring, and the butenyl structure exists in the form of two isomers, syn and anti. Due to the limitation of ligands around neodymium and aluminum, the anti structure will convert to the syn structure, which is more stable kinetically; In the chain growth stage, the newly added butadiene molecules first coordinate with the neodymium and aluminum in the newly formed active center through π bond, and preferentially occupy the side with smaller steric hindrance. The direction of its double bond is limited by the space of the ligands around neodymium, and keeps the same cis configuration as the original butenyl group, thereby realizing chain growth; In the polymerization termination stage, the hydroxyl group in ethanol attacks the Nd-C bond between the neodymium active center and the carbon chain as a nucleophile, and the lone pair of electrons of the hydroxyl oxygen coordinates with Nd 3+ Meanwhile, the hydrogen atom is transferred to the end group of the carbon chain, the Nd-C bond is broken, a stable Nd-O bond and a C-H bond at the end of the polybutadiene chain are formed, thereby realizing the separation of the carbon chain and the neodymium.

[0012]

[0013] Preferably, all the reagents used are commercially available, and the hydrogen-containing silicone oil belongs to low hydrogen-containing oligomeric silicone oil.

[0014] Preferably, in the condensation operation, the cyclohexane in the glue solution and the unreacted butadiene are taken out by steam, condensed by the overhead condensation system, and then recycled to the solvent-monomer recovery device, and the rubber is precipitated from the water in the form of rubber particles with a particle size of 1-3 mm, and then transported to the subsequent dehydration process through the bottom discharge port.

[0015] Preferably, the butadiene polymer obtained in S3 is raw rubber, high wear-resistant carbon black, vulcanizing agent, accelerator, anti-aging agent 6 and plasticizer are added to the polymerized product, mixed uniformly, shaped by a rubber injection machine, and then subjected to a vulcanization step to obtain a finished rubber material.

[0016] Compared with the prior art, the present application has the following beneficial effects: 1、The present application introduces chloroethyl dimethylamine and tetrahydrofuran groups through the active hydrogen on indole, thereby introducing N-containing ligands, and tetrahydrofuran and chloroethyl dimethylamine have large steric hindrance, forming a limited coordination environment around the metal center, thereby realizing high stereoselective control of butadiene polymerization. 3+ Traditional neodymium carboxylate or neodecanoate catalysts only coordinate with Nd

[0017] The alkyl aluminum reagent and the organic boron reagent are respectively used as a cocatalyst and a stabilizer to form a composite catalytic system with the neodymium complex catalyst. 3+ After pre-activation, a neodymium-aluminum binary active center is formed, the organic boron reagent does not directly participate in alkylation, and the electronic environment of the Nd

[0018] 2、In order to solve the problems of poor mixing, difficult heat dissipation and easy gelation caused by the rapid increase of viscosity of the system in the later stage of the traditional process, the application starts from two aspects of dispersant and polymerization process, first, the modification of long alkyl chain to hydrogen-containing silicone oil is completed by using the hydrosilylation reaction, the long-chain alkyl chain has good compatibility with polybutadiene, the activity space between the molecular chains is increased, the polysilane chain has low surface tension, is distributed between the high molecular chains, effectively reduces the friction resistance between the molecular chains, and the Si-O-Si bond can be used as the rigid skeleton of the polymer, and the strength of the finished rubber is improved.

[0019] Secondly, the solvent gradient polymerization process is adopted, the polymerization reaction is carried out in the solvent environment, 2 / 3 of the catalyst is added in the polymerization kettle 1, the side reaction caused by the too large viscosity and the too high temperature of the system is prevented, the low-temperature polymerization is carried out, the conversion rate in the kettle is 50-60% at this time, the remaining catalyst is added in the polymerization kettle 2, the polymerization is carried out at a higher temperature, the inactivated active center is supplemented, the chain growth and structure rearrangement are promoted under the assistance of the dispersant, the high monomer conversion rate (≥90%) and the shorter total reaction time are realized while the high cis-structure is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a continuous polymerization process flow chart of rare earth butadiene rubber of the application; Figure 2 It is the nuclear magnetic hydrogen spectrum of the ligand required by the neodymium complex of the application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments.

[0022] Embodiment 1: S1, preparation of neodymium complex catalyst system S101, in the basic dimethyl sulfoxide solvent, 10% of indole in the total mass of the system is added, stirring and dissolving, under the ice water bath, 11-13% of chloroethyl dimethylamine hydrochloride in the total mass of the system is gradually added, the reaction is carried out for 4h, three times the volume of ice water is added to the system, ethyl acetate is extracted three times, the combined organic phase is washed with saturated sodium chloride solution, filtered, rotary evaporated under reduced pressure, and chromatographed with petroleum ether and ethyl acetate 1:1 to obtain 1-(N,N-dimethylaminoethyl) indole; S102, dissolve 1-(N,N-dimethylaminoethyl)indole in acetic acid, add 8% of the total mass of the system tetrahydro-pyrrole, stirring under ice water bath, add 30wt% formaldehyde solution, react for 3h, add three times the volume of sodium hydroxide solution, dichloromethane extraction, saturated sodium chloride solution washing, filtration, rotary evaporation under reduced pressure, methanol and dichloromethane 1:1 chromatography, the chromatograph and equimolar ratio of neodymium chloride in n-hexane, stirring for 3h, vacuum, n-hexane and toluene mixture extraction, low temperature for 3 days, filtration to obtain neodymium complex catalyst; S2, preparation of long-chain alkane modified polysilane dispersant S201, mix sodium bicarbonate and 1,3-divinyl tetramethyl disiloxane uniformly according to mass ratio 1:2.5, heat to 50℃, slowly add chloroplatinic acid-isopropyl alcohol-toluene mixed solution to the system, 60℃ for 1h, heat to 70℃ for 2h, low temperature for 10h, rotary evaporation under reduced pressure, dilution to obtain platinum catalyst; S202, add 1% of the total mass of the system inhibitor solution to the pretreated hydrogen-containing silicone oil, stir, pass 10min nitrogen, heat to 55℃, mix platinum catalyst and 1-octadecene uniformly according to mass ratio 1:300, slowly add to the hydrogen-containing silicone oil, continue to react for 2.5h, 5% of the total mass of the system neutral alumina, stir for 30min, suction filtration, rotary evaporation of the filtrate under reduced pressure for 2h, add anhydrous sodium sulfate and stand, filter to obtain long-chain alkane modified polysilane dispersant; S3, continuous polymerization process of rare earth butadiene rubber Mix neodymium complex catalyst, ethyl aluminum chloride and organic boron reagent uniformly according to the ratio of Nd:Al:B=1:15:2, pre-activate at 35℃ for 45min, 2 / 3 volume of activated catalyst and 15wt% butadiene-cyclohexane solution after dehydration and deoxidation are continuously fed into polymerization kettle 1, react at 60℃ for 1.5h, transfer into polymerization kettle 2, start stirring, add 1 / 3 volume of activated catalyst, 0.3% of the total mass of the system long-chain alkane modified polysilane dispersant, stay at 80℃ for 2h, add 8wt% ethanol and 0.2wt% 2,6-di-tert-butyl-p-cresol aqueous solution to terminate the reaction, the glue liquid is condensed by hot water and steam, dehydrated and dried, pressed into a block to obtain rare earth butadiene rubber.

[0023] Example 2: S1, preparation of neodymium complex catalyst system S101, in the basic dimethyl sulfoxide solvent, 10% of indole is added to the total mass of the system, stirring and dissolving, under ice water bath, 11-13% of chloroethyl dimethylamine hydrochloride is gradually added to the total mass of the system, reacting for 4h, adding three times the volume of ice water, extracting with ethyl acetate three times, washing the combined organic phase with saturated sodium chloride solution, filtering, rotary evaporation under reduced pressure, chromatography with petroleum ether and ethyl acetate 1:1 to obtain 1-(N,N-dimethylaminoethyl) indole; S102, 1-(N,N-dimethylaminoethyl) indole is dissolved in acetic acid, 8% of tetrahydropyrrole is added to the total mass of the system, stirring under ice water bath, adding 30wt% formaldehyde aqueous solution, reacting for 3h, adding three times the volume of sodium hydroxide solution, extracting with dichloromethane, washing with saturated sodium chloride solution, filtering, rotary evaporation under reduced pressure, chromatography with methanol and dichloromethane 1:1, placing the chromatography product and equimolar neodymium chloride in n-hexane, stirring for 3h, vacuumizing, extracting with n-hexane and toluene mixture, standing at low temperature for 3 days, filtering to obtain neodymium complex catalyst; S2, preparation of long-chain alkane modified polysilane dispersant S201, sodium bicarbonate and 1,3-divinyl tetramethyl disiloxane are mixed uniformly at a mass ratio of 1:2.5, the temperature is raised to 50℃, chloroplatinic acid-isopropyl alcohol-toluene mixed solution is slowly added to the system, 60℃ for 1h, the temperature is raised to 70℃ and reacted for 2h, low temperature standing for 10h, rotary evaporation under reduced pressure, dilution to obtain platinum catalyst; S202, 1% of inhibitor solution is added to the pretreated hydrogen-containing silicone oil, stirring, passing nitrogen for 10min, the temperature is raised to 55℃, the platinum catalyst is mixed uniformly with 1-octadecene at a mass ratio of 1:300, slowly added to the hydrogen-containing silicone oil, continue to react for 2.5h, 5% of neutral alumina is added to the total mass of the system, stirring for 30min, suction filtration, the filtrate is rotary evaporated under reduced pressure for 2h, anhydrous sodium sulfate is added and stood, filtering to obtain long-chain alkane modified polysilane dispersant; S3, continuous polymerization process of rare earth butadiene rubber The neodymium complex catalyst, ethyl chloroaluminum and organic boron reagent are mixed uniformly at a ratio of Nd:Al:B=1:15:2, pre-activated at 35℃ for 45min, 2 / 3 volume of the activated catalyst is continuously added to polymerization kettle 1 with dehydrated and deoxidized 35wt% butadiene-cyclohexane solution, reacted at 60℃ for 1.5h, transferred to polymerization kettle 2, stirring is started, 1 / 3 volume of the activated catalyst and 0.3% of long-chain alkane modified polysilane dispersant are added to the total mass of the system, stay at 80℃ for 2h, 8wt% of ethanol and 0.2wt% of 2,6-di-tert-butyl-p-cresol aqueous solution are added to terminate the reaction, the glue liquid is condensed by hot water and steam, dehydrated and dried, pressed into a block to obtain rare earth butadiene rubber.

[0024] Example 3: S1, Preparation of neodymium complex catalyst system S101, 10% indole of total system mass was added in dimethyl sulfoxide solvent with alkaline, stirred and dissolved, 11-13% chloroethyl dimethylamine hydrochloride of total system mass was gradually added under ice water bath, reacted for 4h, three times volume of ice water was added, extracted with ethyl acetate for three times, washed with saturated sodium chloride solution, filtered, rotary evaporated under reduced pressure, chromatographed with petroleum ether and ethyl acetate 1:1 to obtain 1-(N,N-dimethylaminoethyl)indole; S102, 1-(N,N-dimethylaminoethyl)indole was dissolved in acetic acid, 8% tetrahydropyrrole of total system mass was added, stirred under ice water bath, 30wt% formaldehyde aqueous solution was added, reacted for 3h, three times volume of sodium hydroxide solution was added, extracted with dichloromethane, washed with saturated sodium chloride solution, filtered, rotary evaporated under reduced pressure, chromatographed with methanol and dichloromethane 1:1, the chromatographed material was placed in n-hexane with equimolar neodymium chloride, stirred and reacted for 3h, vacuumized, extracted with n-hexane and toluene mixture, low-temperature standing for 3 days, filtered to obtain neodymium complex catalyst; S2, Preparation of long-chain alkane modified polysilane dispersant S201, sodium bicarbonate and 1,3-divinyl tetramethyl disiloxane were mixed uniformly according to mass ratio 1:2.5, the system was slowly added with chloroplatinic acid-isopropyl alcohol-toluene mixed solution, heated to 60℃ for 1h, heated to 70℃ for 2h, low-temperature standing for 10h, rotary evaporated under reduced pressure, diluted to obtain platinum catalyst; S202, 1% inhibitor solution of total system mass was added in pretreated hydrogen-containing silicone oil, stirred, passed with nitrogen for 10min, heated to 55℃, the platinum catalyst was mixed uniformly with 1-octadecene according to mass ratio 1:300, slowly added into the hydrogen-containing silicone oil, continued to react for 2.5h, 5% neutral alumina of total system mass was stirred for 30min, filtered, the filtrate was rotary evaporated under reduced pressure for 2h, added with anhydrous sodium sulfate and stood, filtered to obtain long-chain alkane modified polysilane dispersant; S3, Continuous polymerization process of rare earth butadiene rubber Neodymium complex catalyst, ethyl chloroaluminum and organic boron reagent were mixed uniformly according to the ratio of Nd:Al:B=1:15:2, pre-activated at 35℃ for 45min, 2 / 3 volume of the activated catalyst was mixed with 25wt% butadiene-cyclohexane solution after dehydration and deoxidization, the relevant continuous polymerization process flow was as follows Figure 1The reaction material is continuously fed into the polymerization kettle 1, and the reaction is carried out at 60℃ for 1.5h. Then the stirring is started, and 1 / 3 volume of the activated catalyst, 0.3% long-chain alkane modified polysilane dispersant based on the total mass of the system are added. The reaction is carried out at 80℃ for 2h. Then 8wt% ethanol and 0.2wt% 2,6-di-tert-butyl-p-cresol aqueous solution are added to terminate the reaction. The glue liquid is condensed by hot water and steam, dehydrated and dried, pressed into a block, and rare earth butadiene rubber is obtained.

[0025] Example 4: S1, preparation of neodymium complex catalyst system S101, in the basic dimethyl sulfoxide solvent, 10% indole based on the total mass of the system is added, stirred and dissolved. Under ice water bath, 11-13% chloroethyl dimethylamine hydrochloride based on the total mass of the system is gradually added, and the reaction is carried out for 4h. Then three times volume of ice water is added, and the organic phase is extracted with ethyl acetate for three times. The combined organic phase is washed with saturated sodium chloride solution, filtered, and rotary evaporated under reduced pressure. Petroleum ether and ethyl acetate 1:1 are used for chromatography, and 1-(N,N-dimethylaminoethyl) indole is obtained. S102, 1-(N,N-dimethylaminoethyl) indole is dissolved in acetic acid, and 8% tetrahydropyrrole based on the total mass of the system is added. Stirring is carried out under ice water bath, and 30wt% formaldehyde aqueous solution is added. The reaction is carried out for 3h. Then three times volume of sodium hydroxide solution is added, and dichloromethane is used for extraction. The organic phase is washed with saturated sodium chloride solution, filtered, and rotary evaporated under reduced pressure. Methanol and dichloromethane 1:1 are used for chromatography. The chromatographed material is mixed with equimolar neodymium chloride in n-hexane, stirred and reacted for 3h. Vacuum is applied, and n-hexane and toluene mixture is used for extraction. The mixture is left to stand at low temperature for 3 days, and filtered to obtain the neodymium complex catalyst. S2, preparation of long-chain alkane modified polysilane dispersant S201, sodium bicarbonate and 1,3-divinyl tetramethyl disiloxane are mixed uniformly at a mass ratio of 1:2.5, and the temperature is raised to 50℃. Chloroplatinic acid-isopropyl alcohol-toluene mixed solution is slowly added to the system, and the temperature is kept at 60℃ for 1h. The temperature is raised to 70℃ for 2h, and the mixture is left to stand at low temperature for 10h. Rotary evaporation is carried out under reduced pressure, and the platinum catalyst is obtained by dilution. S202, 1% inhibitor solution based on the total mass of the system is added to the pretreated hydrogen-containing silicone oil, and stirred. Nitrogen is introduced for 10min, and the temperature is raised to 55℃. The platinum catalyst is mixed uniformly with 1-octadecene at a mass ratio of 1:300, and slowly added to the hydrogen-containing silicone oil. The reaction is carried out for 2.5h. 5% neutral alumina based on the total mass of the system is added, and stirred for 30min. Filtration is carried out, and the filtrate is rotary evaporated under reduced pressure for 2h. Anhydrous sodium sulfate is added, and left to stand. Filtration is carried out to obtain the long-chain alkane modified polysilane dispersant. S3, continuous polymerization process of rare earth butadiene rubber Neodymium complex catalyst, ethyl chloro aluminum and organic boron reagent were mixed uniformly according to the ratio of Nd: Al: B = 1: 5: 2, pre-activated at 35℃ for 45min, 2 / 3 volume of activated catalyst and 25wt% butadiene-cyclohexane solution after dehydration and deoxidation were continuously added into polymerization kettle 1, reacted at 60℃ for 1.5h, transferred into polymerization kettle 2, started stirring, then added 1 / 3 volume of activated catalyst, 0.3% long-chain alkane modified polysilane dispersant in total system mass, 8wt% ethanol and 0.2wt% 2, 6-di-tert-butyl-p-cresol aqueous solution to terminate the reaction, the glue liquid was condensed by hot water and steam, dehydrated and dried, pressed into a block, and rare earth butadiene rubber was obtained.

[0026] Example 5: S1, preparation of neodymium complex catalyst system S101, 10% indole in total system mass was added in basic dimethyl sulfoxide solvent, stirred and dissolved, 11-13% chloroethyl dimethylamine hydrochloride in total system mass was gradually added under ice water bath, reacted for 4h, 3 times volume of ice water was added, extracted with ethyl acetate for 3 times, washed with saturated sodium chloride solution, filtered, rotary evaporated under reduced pressure, chromatographed with petroleum ether and ethyl acetate 1:1 to obtain 1-(N,N-dimethylaminoethyl) indole; S102, 1-(N,N-dimethylaminoethyl) indole was dissolved in acetic acid, 8% tetrahydropyrrole in total system mass was added, stirred under ice water bath, 30wt% formaldehyde aqueous solution was added, reacted for 3h, 3 times volume of sodium hydroxide solution was added, extracted with dichloromethane, washed with saturated sodium chloride solution, filtered, rotary evaporated under reduced pressure, chromatographed with methanol and dichloromethane 1:1, the chromatographed material was placed in n-hexane with equimolar neodymium chloride, stirred and reacted for 3h, vacuumized, extracted with n-hexane and toluene mixture, low-temperature standing for 3 days, filtered to obtain neodymium complex catalyst; S2, preparation of long-chain alkane modified polysilane dispersant S201, sodium bicarbonate and 1,3-divinyl tetramethyl disiloxane were mixed uniformly according to the mass ratio of 1:2.5, heated to 50℃, and chloroplatinic acid-isopropyl alcohol-toluene mixed solution was slowly added into the system, incubated at 60℃ for 1h, heated to 70℃ for 2h, low-temperature standing for 10h, rotary evaporated under reduced pressure, and diluted to obtain platinum catalyst; S202, 1% inhibitor solution in total system mass was added into pretreated hydrogen-containing silicone oil, stirred, and passed 10min nitrogen, heated to 55℃, platinum catalyst and 1-octadecene were mixed uniformly according to the mass ratio of 1:300, slowly added into hydrogen-containing silicone oil, and continuously reacted for 2.5h, 5% neutral alumina in total system mass was stirred for 30min, vacuum filtered, the filtrate was rotary evaporated under reduced pressure for 2h, anhydrous sodium sulfate was added and stood, and filtered to obtain long-chain alkane modified polysilane dispersant; S3, continuous polymerization process of rare earth butadiene rubber Neodymium complex catalyst, ethyl chloro aluminum and organic boron reagent were mixed uniformly according to the ratio of Nd:Al:B=1:25:2, pre-activated at 35℃ for 45min, 2 / 3 volume of activated catalyst and 25wt% butadiene-cyclohexane solution after dehydration and deoxidation were continuously put into polymerization kettle 1, reacted at 60℃ for 1.5h, transferred into polymerization kettle 2, started stirring, then added 1 / 3 volume of activated catalyst, 0.3% long-chain alkane modified polysilane dispersant in total system mass, stayed at 80℃ for 2h, added 8wt% ethanol and 0.2wt% 2,6-di-tert-butyl-p-cresol aqueous solution to terminate the reaction, the glue liquid was condensed by hot water and steam, dehydrated and dried, pressed into a block, and rare earth butadiene rubber was obtained.

[0027] Comparative example 1: Compared with example 3, 2 / 3 activated catalyst and 30wt% butadiene-cyclohexane solution were mixed and reacted in polymerization kettle 1.

[0028] Comparative example 2: Compared with example 3, neodymium complex catalyst, ethyl chloro aluminum and organic boron reagent were mixed according to the ratio of Nd:Al:B=1:35:2.

[0029] Comparative example 3: Compared with example 3, 2-chloroethyl tetrahydrofuran was gradually added to the indole solution in S101 for reaction.

[0030] Comparative example 4: Compared with example 3, in S102, 1-(N,N-dimethylaminoethyl)indole was dissolved in tetrahydrofuran, 1-2% n-butyllithium was slowly added under ice water bath condition, 8-10% chloroethyl dimethylamine hydrochloride in total system mass was added, reacted for 2-3h, three times volume of ice water was added, extracted with ethyl acetate for three times, washed with saturated sodium chloride solution, filtered, rotary evaporated under reduced pressure, chromatographed with petroleum ether and ethyl acetate 1:1, and filtered to obtain neodymium complex catalyst.

[0031] Comparative example 5: Compared with example 3, neodymium neodecanoate / ethyl chloro aluminum / organic boron reagent was used as butadiene polymerization catalyst.

[0032] Comparative example 6: Compared with example 3, neodymium complex / methyl chloro aluminum / organic boron reagent was used as butadiene polymerization catalyst.

[0033] Comparative example 7: Compared with example 3, neodymium complex / methyl chloro aluminum was used as butadiene polymerization catalyst.

[0034] Comparative example 8: Compared to Example 3, pretreated hydrogen-containing silicone oil was used directly as a dispersant without long-chain alkane modification.

[0035] Comparative Example 9: Compared to Example 3, the mass ratio of hydrogen-containing silicone oil to octadecene is 3:1.

[0036] Performance testing: According to the standards and testing methods of GB / T1232.1 "Determination of unvulcanized rubber by disc shear viscometer - Part 1: Determination of Mooney viscosity", SH / T1727 "Determination of microstructure of butadiene rubber by infrared spectroscopy", GB / T528 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", and GB / T24131.1 "Determination of volatile content in raw rubber - Part 1: Hot roller method and oven method", the rare earth cis-butadiene rubber prepared in this invention was tested for Mooney viscosity, cis content, tensile strength, and elongation.

[0037] Table 1. Performance test data of each group of butadiene rubber

[0038] Data Analysis: In Comparative Example 3, 2-chloroethyltetrahydrofuran was gradually added to the indole solution. The active hydrogen on the chloropyrrole was bound, and the other steps remained unchanged. Therefore, the final structural formula of the neodymium complex catalyst is:

[0039] The 1H NMR spectrum of the ligand required for the neodymium complex prepared in Example 3 is shown below. Figure 2 As shown in the figure, the multiplets near 7.0-7.5 ppm correspond to hydrogen atoms on the indole benzene ring, and the peaks near 3.0-4.0 ppm correspond to methylene hydrogen atoms directly bonded to the N atom. This matches the environmental characteristics of the methylene hydrogen bonded to N in ethyldimethylamine and the methylene hydrogen bonded to O in tetrahydrofuran, demonstrating that ethyldimethylamine and tetrahydrofuran have been successfully attached to the indole molecule. Table 1 shows that the cis content of the rubber in Comparative Example 3 is lower than that in Example 3, and the tensile strength and elongation are also lower, while the Mooney viscosity shows no significant change. This can be explained by the change in reagents causing a change in the ligands of the Nd:N complex catalyst. Both sides are tetrahydrofuran. Although tetrahydrofuran is more rigid than ethyldimethylamine, has greater binding restriction on butadiene, and higher stereoselectivity, the large steric hindrance of the tetrahydrofuran group may prevent butadiene from coordinating with the Nd:N active center, thus reducing the cis content. Cis-butadiene rubber has better performance; therefore, the more cis structures, the higher the tensile strength and elongation. Compared to Example 3, Comparative Example 4 also features a change in the ligands of the neodymium complex catalyst. Chloroethyl dimethylamine was used for secondary binding, resulting in the following neodymium complex catalyst:

[0040] The content of cis in the comparative example 4 is lower than that in the comparative example 3, and the tensile strength and tensile rate also slightly decrease, because the restriction of ethyldimethylamine is smaller than that of tetrahydrofuran, although butadiene can quickly combine with the neodymium active center, the restriction of butadiene combination is small, and the trans structure is easy to generate, resulting in the decrease of the content of cis, the winding of the polymer cis and trans, and the increase of the Mooney viscosity.

[0041] The comparative example 5 uses the traditional neodymium neodecanoate as the catalyst, and the example 3 is the neodymium complex of the self-made indole derivative ligand. In the example 3, the ligand can accurately control the electronic environment and steric hindrance of the neodymium active center, strengthen the directional nature of butadiene cis insertion, and the ligand of neodecanoate neodymium has weak regulation ability, the active center is insufficiently constrained in the direction of insertion, the cis selectivity decreases, and even branching is easy, the Mooney viscosity is large, and the mechanical properties are also poor than the example 3 due to the poor stability of the active center.

[0042] The comparative example 6 uses methyl chloroaluminum instead of ethyl chloroaluminum in the example 3 as a cocatalyst. The difference between methyl chloroaluminum and ethyl chloroaluminum is the alkyl group. The alkylating ability of ethyl chloroaluminum is stronger than that of methyl. Both ethyl and methyl belong to dimers, one side is combined with neodymium, and the other side is combined with aluminum to form a neodymium-aluminum double active center. The steric hindrance of methyl is smaller than that of ethyl, and the ability of steric and electronic regulation of the active center is weakened. The directional nature of butadiene insertion decreases, and the cis selectivity and mechanical properties are thus inferior to the example 3.

[0043] The comparative example 7 does not add organic boron reagent. The organic boron reagent can stabilize the neodymium active center through electronic effect, inhibit side reactions and strengthen the directional nature of cis insertion. After the lack of boron, the electronic environment of the active center is unbalanced, the stability decreases, the non-cis insertion of butadiene increases, and the uneven distribution of the active center leads to abnormal molecular weight and crosslinking degree of the polymer product. Finally, the Mooney viscosity significantly decreases, and the mechanical properties and cis selectivity are both inferior to the example 3.

[0044] The comparative example 8 uses unmodified hydrogen-containing silicone oil instead of long-chain alkane modified polysilane dispersant in the example 3. The long-chain alkane group can adapt to the rubber system, improve the uniformity of the catalyst dispersion, and ensure that the active center efficiently and consistently participates in the reaction. The unmodified dispersant is insufficient in compatibility and dispersion ability, leading to local agglomeration of the catalyst, increased system viscosity, and serious polymer wall hanging phenomenon in the polymerization kettle 2. The reaction rate and product structure regularity decrease, and thus the tensile properties and cis selectivity of the comparative example 8 are weakened, which are lower than those of the example 3.

[0045] Comparative Example 9 changes the mass ratio of hydrogen-containing silicone oil to octadecene to 3:1, the ratio in Example 3 is 4:1, which can ensure that the hydrogen in the hydrogen-containing silicone oil is replaced by long-chain alkanes. Imbalance of the ratio will lead to insufficient grafting of long-chain alkanes on polysilane, and the space steric hindrance and compatibility of the dispersant will decrease, which cannot effectively disperse the catalyst, and the local concentration of active centers fluctuates, which makes the polymerization reaction uneven, and the overall performance of the rubber decreases slightly.

[0046] In Examples 1, 2, 3 and Comparative Example 2, the content of butadiene is 15%, 25%, 20% and 30% respectively, and the overall performance of the prepared rubber is in the order of Example 3 > Example 1 > Example 2 > Comparative Example 1. This can be explained as follows: butadiene is a monomer required for the polymerization of cis-butadiene rubber, and the more the content, the faster the polymerization speed at the beginning of the polymerization stage. Therefore, in Comparative Example 1, the system in the polymerization kettle 1 becomes viscous after 30 min of reaction, but as the reaction proceeds, the butadiene monomer is in excess, and there is still some left at the end of the polymerization, part of which is removed in the post-processing step, and part is mixed with the polymer to become raw rubber. However, the performance of butadiene monomer is not as good as that of the polymer, so the more the amount of butadiene monomer doped in the polymer, the worse the performance of the rubber, but the Mooney viscosity will increase. When the content of butadiene monomer is high, most of it is catalyzed by neodymium complex catalyst to undergo cis-polymerization, part of it undergoes trans-polymerization, and part of it undergoes dimerization side reaction at high temperature and high monomer concentration:

[0047] There are also double bonds in the dimer, so they will affect the polymerization of butadiene. The presence of dimers causes an increase in branching, and the Mooney viscosity of the polymer will also increase.

[0048] In example 3, 4, 5 and comparative example 1, the content of ethyl chloro aluminum is 5, 25, 15, 35 respectively, and the cis content of the polymer in example 3 is higher than that in example 2, higher than that in example 1, and higher than that in comparative example 5. Ethyl aluminum exists in the catalyst system as a cocatalyst, alkylates the main catalyst to generate metal alkyl active centers with polymerization activity, and promotes the coordination and cis insertion of butadiene monomers in the active center, ensuring efficient polymerization. In example 1, the content of ethyl chloro aluminum is insufficient, the alkylization of the main catalyst is insufficient, the amount of active centers generated is small, the polymerization activity is reduced, and the structure of the active center is unstable, the selectivity of butadiene cis insertion is reduced, the cis content of the rubber is low, the molecular weight is high due to the small amount of active centers, the Mooney viscosity is increased, the content in example 3 is appropriate, the active center generation efficiency is high and the structure is stable, the cis insertion directionality is strong, the cis content of the rubber is high, the molecular weight distribution is uniform, the Mooney viscosity is moderate, the mechanical properties such as tensile strength and elongation are optimal, the content in example 2 and comparative example 1 is excessive, and the excess ethyl chloro aluminum will excessively destroy the spatial configuration of the active center, and also cause chain transfer reaction, resulting in reduced molecular weight, decreased Mooney viscosity, and poor cis selectivity, and the residual cocatalyst is increased, which weakens the processing stability and mechanical properties of the rubber.

[0049] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and the inventive concept of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A continuous polymerization process for the preparation of rare earth butadiene rubber, characterized in that, Comprising the following steps: S1, preparation of neodymium complex catalyst system S101, in the basic dimethyl sulfoxide solvent, add 10% of the total mass of the system indole, stirring and dissolving, under ice water bath, gradually add 11-13% of the total mass of the system chloroethyl dimethylamine hydrochloride, reaction for 4-5h, add three times the volume of ice water, extract with ethyl acetate three times, wash the combined organic phase with saturated sodium chloride solution, filter, rotary evaporation under reduced pressure, chromatography with petroleum ether and ethyl acetate 1:1 to obtain 1-(N,N-dimethylaminoethyl) indole; S102, dissolve 1-(N,N-dimethylaminoethyl) indole in acetic acid, add 8-10% of the total mass of the system tetrahydropyrrole, stirring under ice water bath, add 30wt% formaldehyde solution, reaction for 3-4h, add three times the volume of sodium hydroxide solution, dichloromethane extraction, saturated sodium chloride solution washing, filtration, rotary evaporation under reduced pressure, chromatography with methanol and dichloromethane 1:1, the chromatography and equimolar neodymium chloride are placed in n-hexane, stirring for 3h, vacuum, n-hexane and toluene mixture extraction, low temperature standing for 3 days, filtration to obtain neodymium complex catalyst; S2, preparation of long-chain alkane modified polysilane dispersant S201, mix sodium bicarbonate and 1,3-divinyl tetramethyl disiloxane in a mass ratio of 1:2.5, heat to 50℃, slowly add chloroplatinic acid-isopropyl alcohol-toluene mixed solution to the system, 60℃ for 1h, heat to 65-70℃ for 2h, low temperature standing for 10h, rotary evaporation under reduced pressure, dilution to obtain platinum catalyst; S202, add 1% of the total mass of the system inhibitor solution to the pretreated hydrogen-containing silicone oil, stir, pass 10min nitrogen, heat to 55℃, mix the platinum catalyst and 1-octadecene in a mass ratio of 1:300, slowly add to the hydrogen-containing silicone oil, continue to react for 2.5h, add 5% of the total mass of the system neutral alumina, stir for 30min, filter, rotary evaporation of the filtrate under reduced pressure for 2h, add anhydrous sodium sulfate and stand, filter to obtain long-chain alkane modified polysilane dispersant; S3, continuous polymerization process of rare earth butadiene rubber Mix neodymium complex catalyst, ethyl chloroaluminum and organic boron reagent in a ratio of Nd:Al:B=1:5-25:2, pre-activate at 30-40℃ for 30-60min, 2 / 3 volume of activated catalyst and dehydrated and deoxygenated butadiene-cyclohexane solution are continuously fed into polymerization kettle 1, react at 50-70℃ for 1-2h, transfer to polymerization kettle 2, start stirring, add 1 / 3 volume of activated catalyst, 0.1-0.5% of the total mass of the system long-chain alkane modified polysilane dispersant, stay at 70-90℃ for 1.5-3h, add 5-10wt% ethanol and 0.1-0.2wt% 2,6-di-tert-butyl-p-cresol aqueous solution to terminate the reaction, the glue liquid is condensed by hot water and steam, dehydrated and dried, pressed into a block to obtain rare earth butadiene rubber.

2. The continuous polymerization process for the preparation of rare earth butadiene rubber according to claim 1, characterized in that, The preparation method of the basic dimethyl sulfoxide solvent in S101 is as follows: mix dimethyl sulfoxide and 10-15wt% sodium hydroxide solution in a volume ratio of 8:1, control the pH of the system to 10-11.

3. The continuous polymerization process for the preparation of rare earth butadiene rubber according to claim 1, characterized in that, The mass ratio of 1-(N,N-dimethylaminoethyl) indole to acetic acid in S102 is 1:8, the amount of n-hexane is 6 times the total mass of 1-(N,N-dimethylaminoethyl) indole eluate and neodymium chloride, and the mass ratio of n-hexane to toluene is 3:

1.

4. The continuous polymerization process for the preparation of rare earth butadiene rubber according to claim 1, characterized in that, In S201, hexachloroplatinic acid hexahydrate dried under vacuum at 80℃ for 1h is added to isopropyl alcohol-toluene dehydrated by 4Å molecular sieves for 24h, the mass ratio of hexachloroplatinic acid hexahydrate, isopropyl alcohol and toluene is 1:10:10, nitrogen is passed for 15min after pre-mixing, stirring is carried out at room temperature for 30-40min, filtration is carried out on a filter membrane, and low-temperature refrigeration is used for standby.

5. The continuous polymerization process for the preparation of rare earth butadiene rubber according to claim 1, characterized in that, In S202, the molecular weight of the hydrogen-containing silicone oil is between 600-800Da, the hydrogen content is 0.1-0.3%, the pretreatment step of the hydrogen-containing silicone oil is vacuum distillation at 80℃ and -0.09MPa for 1h, and the preparation method of the inhibitor solution is that acetylenylcyclohexanol is dissolved in anhydrous toluene to form a 1wt% solution, and the mass ratio of the hydrogen-containing silicone oil to octadecane is 4:

1.

6. The continuous polymerization process for the preparation of rare earth butadiene rubber according to claim 1, characterized in that, In S3, the organic boron reagent is [Ph3C][B(C6F5)]4, the mass fraction of butadiene in cyclohexane is 15-35%, the reaction conversion rate in polymerization kettle 1 is controlled to be 50-60%, and the reaction conversion rate in polymerization kettle 2 is ≥90%.

7. The continuous polymerization process for the preparation of rare earth butadiene rubber according to claim 1, characterized in that, In S3, after the reaction is terminated, the glue solution is pumped into a stirring coagulation kettle, hot water is added according to a volume ratio of glue solution to hot water of 1:3-5 at 80-90℃, saturated steam at 100-110℃ is introduced, the amount of saturated steam introduced is 10-15% of the mass of the glue solution, stirring is carried out for 1-2h, and then drying and briquetting processes are entered to obtain rare earth butadiene rubber.

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