A polyether macromonomer and its preparation method

Abstract

This invention provides a polyether macromonomer and its preparation method. First, an initiator, a small-molecule alcohol, and a catalyst are mixed and reacted until a clear solution is obtained, yielding an activated initiator. The activated initiator is then transferred to a primary reaction apparatus, where epoxides are introduced to obtain a polyether intermediate. The polyether intermediate is then transferred to a secondary reaction apparatus to prepare the polyether macromonomer. Compared with existing technologies, this invention, through optimized process and setup design, not only improves production efficiency but also produces polyether macromonomers with superior hydroxyl value, number-average molecular weight, double bond retention rate, and effective content.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to a polyether macromonomer and its preparation method. Background Technology

[0002] Polycarboxylate superplasticizers are third-generation high-performance concrete superplasticizers and are currently the most widely used type of superplasticizer in commercial concrete. Their molecular structure is comb-like, and the adsorption groups and polyether side chains can be adjusted. They possess advantages such as strong molecular structure designability, low dosage, high water reduction rate, and good workability. They can significantly reduce cement usage or increase concrete strength in commercial concrete, playing a vital role in the green production of commercial concrete and the reduction of carbon emissions.

[0003] Polyether macromonomers are one of the core raw materials of polycarboxylate superplasticizers, accounting for more than 80% of the superplasticizer's mass. The quality of polyether macromonomers has a significant impact on the performance of superplasticizers. The molecular structures of polyether macromonomers include ester type and ether type (Liu Guanjie et al., Research progress on the application of polyether macromonomers in polycarboxylate superplasticizers [J], Daily Chemical Science, 2018, 41(10), 13-16). Ester type polyether macromonomers use unsaturated carboxylic acids and methoxy polyethers as raw materials, and generally adopt esterification dehydration process, which is relatively complex in terms of preparation and post-treatment methods. Ether type polyether macromonomers use unsaturated alcohols containing double bonds and epoxides as raw materials, and are prepared through anionic ring-opening polymerization process, which is simple and does not require special post-treatment. At present, ether type polyether macromonomers dominate the domestic market and are the most important polyether macromonomer products in China.

[0004] Stirred reactors, BUSS reactors, and PRESS reactors are all commonly used reactors for the polymerization of epoxide alkane. In particular, PRESS reactors have the characteristics of large scale-up and high production efficiency, and are the most widely used in the polyether industry. Currently, the fifth generation of PRESS reactors has been developed, with a single reactor capacity of more than 30 tons, which greatly improves the production efficiency and capacity of polyether macromonomers (Qin Yong, A brief discussion on the development trend of ethoxylation production process in my country [J], Daily Chemical Science, 2014, 37(11), 1-6).

[0005] The production process of polyether macromonomers includes initiator pretreatment (catalyst addition), epoxide ring-opening polymerization, heat preservation and curing, vacuum devolatilization, and polyether slicing. Except for the initiator pretreatment and polyether slicing steps, the other steps are generally carried out sequentially in a PRESS reactor. The epoxide ring-opening polymerization step is the core of the entire polyether macromonomer production process control; improving the mass and heat transfer efficiency during the epoxide ring-opening polymerization process has a significant impact on improving the quality of the polyether macromonomer.

[0006] Chinese patent CN 204939365U reports a highly efficient and energy-saving reaction device for polyether macromonomers. It adds a horizontal reactor to a traditional PRESS reactor, forming a reactor structure with two horizontal reactors and a vertical collection tank, thereby enhancing the reaction efficiency of ethylene oxide in the horizontal reactor. Chinese patent CN104592507A adds a vertical collection tank to a PRESS reactor, forming a reactor structure with one horizontal reactor and two vertical collection tanks, optimizing the traditional batch production process of the PRESS reactor into a continuous production process and improving the production efficiency of polyether macromonomers. Chinese patents CN205347297U and CN 205275507U, through the heterogeneous design of the shell-and-tube heat exchanger, weaken the boundary layer effect of viscous polyether liquid near the wall plate, improving the mass and heat transfer effect of the viscous polyether liquid.

[0007] Patent publication number CN 105001411A reports a reaction device system for improving the production efficiency of high molecular weight polyether macromonomers. It combines a vertical collection tank in a PRESS reactor with a stirred tank reactor. The vertical collection tank serves as a reaction device for polyether intermediates, while the stirred tank reactor serves as a reaction device for high molecular weight polyethers. This solves the limitations of scale-up in a single reactor and the influence of viscosity of high molecular weight polyether macromonomers, thereby improving the production efficiency of high molecular weight polyether macromonomers.

[0008] In summary, optimizing the reactor structure for polyether macromonomers can improve the mass and heat transfer efficiency of the reaction process between polyether macromonomers and epoxides, thereby increasing the production efficiency of polyether macromonomers, and further enhancing the production efficiency of high molecular weight polyether macromonomers. However, the aforementioned studies primarily focus on reactor structure optimization, with limited attention paid to process optimization. This fails to achieve a synergistic effect between process and equipment optimization, thus limiting the overall improvement in polyether macromonomer production efficiency to some extent. Summary of the Invention

[0009] The purpose of this invention is to provide a polyether macromonomer and its preparation method. Through improvements in both process and equipment, polyether macromonomers are produced with high efficiency. The preparation method is simple, low-cost, and produces products with good performance.

[0010] The specific technical solution of this invention is as follows:

[0011] A method for preparing a polyether macromonomer includes the following steps:

[0012] 1) Mix the initiator, small molecule alcohol, and catalyst, and react until a clear solution is obtained to obtain the activated initiator;

[0013] 2) The activating initiator is transferred to a primary reaction apparatus, and epoxy alkane is introduced to obtain a polyether intermediate;

[0014] 3) The polyether intermediate is transferred to a secondary reaction apparatus to prepare the polyether macromonomer.

[0015] In step 1), the initiator has the following molecular structure: R is H or -CH3; X is -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-CH2-CH2-

[0016] -CH2-CH2-CH2-CH(CH3)-CH2-CH2-, -(CH2)9-, -O-CH2-CH2-,

[0017] One of the following structures: -O-CH2-CH2-O-CH2-CH2-, -O-CH2-CH2-CH2-, -CH2-CH(CH3)-CH2-;

[0018] In step 1), the initiator is selected from allyl alcohol, methyl allyl alcohol, 3-methyl-3-buten-1-ol, 4-methyl-4-penten-1-ol, 7-octen-1-ol, 3,7-dimethyl-7-octen-1-ol, 10-undecenol, isoprene alcohol, ethylene glycol monovinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutylvinyl ether unsaturated alcohol.

[0019] In step 1), the small molecule alcohol, selected from methanol, is continuously added dropwise to the reaction system of step 1). As the molecular weight of the initiator's carbon chain increases, the reactivity of the initiator's hydroxyl groups gradually decreases, easily accumulating at the reaction interface between the catalyst and the initiator, resulting in a significant decrease in the subsequent reactivity of the initiator and catalyst. Methanol is one of the alcohol monomers that reacts fastest with the catalyst. Adding a small amount of methanol dropwise to the initiator can rapidly refresh the reaction interface between the catalyst and the initiator, promoting the reaction rate between the initiator and the catalyst. The amount of the small molecule alcohol used is 10%-30% of the catalyst mass.

[0020] In step 1), the catalyst is selected from metallic sodium, specifically rod-shaped metallic sodium at a concentration of 1.3-1.5 kg / piece. For polyether macromonomers with a number average molecular weight ≤ 3000, the catalyst dosage is 0.25%-0.35% of the initiator mass. For polyether macromonomers with a number average molecular weight > 3000, the catalyst dosage is 0.5%-0.7% of the initiator mass.

[0021] In step 1), the catalyst is always below the liquid level in the reaction system.

[0022] Step 1) The reaction is carried out in a pretreatment device, which includes a batch reactor. A rod-shaped sodium metal feed device is installed on the batch reactor, and the rod-shaped sodium metal feed device is connected to a rod-shaped sodium metal cage via an elastic structure. The rod-shaped sodium metal cage is used to hold the catalyst rod-shaped sodium metal, ensuring that the rod-shaped sodium metal remains submerged below the liquid surface during mechanical stirring. An initiator inlet is provided on the batch reactor for adding the initiator. A small molecule alcohol dropwise inlet is provided on the batch reactor for adding small molecule alcohols. A mechanical stirring device is installed inside the batch reactor for stirring the reaction inside the reactor.

[0023] The batch reactor also includes configurations such as steam heating, circulating water cooling, vacuum, nitrogen protection, and nitrogen replacement.

[0024] In step 1), the rod-shaped sodium metal feeding device is a 50cm×50cm×50cm stainless steel cage. 5-10 rods / cage are placed in the cage and suspended into the kettle reactor, submerged below the surface of the initiator liquid. Furthermore, the stainless steel cage remains submerged below the liquid surface during mechanical stirring.

[0025] In step 1), the reaction refers to the following steps: under nitrogen protection, an initiator and a small molecule alcohol are added sequentially to the pretreatment device, and a rod-shaped metallic sodium is placed in a stainless steel cage and then hoisted into the pretreatment vessel. Under nitrogen protection, mechanical stirring is started.

[0026] In step 1), the reaction is carried out at a temperature between 40-70°C and for a reaction time of 3.0-6.0 h, which yields a clear and transparent activating initiator.

[0027] This invention optimizes the design of the pretreatment vessel by placing rod-shaped metallic sodium in a stainless steel cage, submerged below the initiator liquid surface. This prevents the metallic sodium from softening and sticking to the stirring blades or the inner coil inside the vessel after heating, which could lead to local overheating or insufficient reaction, thus affecting the reaction time between the initiator and the metallic sodium.

[0028] In step 2), the primary reaction device is a commonly used fifth-generation PRESS reactor, which has a horizontal reactor and a vertical collection tank. The large circulation is connected to the horizontal reactor, and the small circulation is connected to the vertical collection tank.

[0029] In step 2), the epoxide hydrocarbons include ethylene oxide, propylene oxide, cyclohexane oxide, styrene oxide, glycidyl ether, butyl glycidyl ether, ethyl glycidyl ether, phenyl glycidyl ether, etc.; preferably, in the epoxide hydrocarbons used, ethylene oxide accounts for 95%-100% of the total amount of epoxide hydrocarbons, and the amount of other epoxide hydrocarbons is 0%-5%.

[0030] In step 2), the primary reaction device only feeds in epoxide alkane without performing curing and devolatilization processes, and the theoretical number-average molecular weight of the prepared polyether macromonomer is ≤3000.

[0031] In step 2), the primary reaction device has a reaction temperature of 115±5℃ and a reaction pressure of ≤450KPa.

[0032] In step 3), the secondary reaction device is a stirred tank reactor with epoxides fed from the bottom. To ensure efficient mass and heat transfer of materials with a certain viscosity within the stirred tank reactor, the epoxides are fed from the bottom. The mechanical agitator has multiple layers of impellers. The material is pumped from the bottom pipeline to the Venturi nozzle device via an external circulation pump, where it is thoroughly mixed with unreacted epoxides from the top of the stirred tank reactor before re-entering the stirred tank reactor. The equipment structure is as follows: Figure 2 As shown.

[0033] The secondary reaction device includes a stirred tank reactor, which is equipped with atomizing nozzles to atomize alkyl epoxides into small particles and spray them into the liquid, thereby improving the mass and heat transfer effects of gas-liquid contact. The stirred tank reactor also includes a multi-layered impeller mechanical agitator for stirring the material reaction within the reactor. The top of the stirred tank reactor is connected to a Venturi nozzle device via a connecting pipeline. Gas and liquid materials at the top of the reactor mix in the Venturi nozzle, further enhancing the gas-liquid mixing effect. The Venturi nozzle device is connected to an external circulation pump via a tubular heat exchanger.

[0034] The secondary reaction unit receives polyether intermediates from the primary reaction unit. Based on the amount of alkyl epoxides fed into the primary reaction unit, the theoretical number-average molecular weight of the polyether intermediate is calculated. If it is the same as the designed number-average molecular weight of the polyether macromonomer, the maturation and devolatilization processes are carried out in the secondary reaction unit. If it is less than the designed number-average molecular weight of the polyether macromonomer, the remaining amount of alkyl epoxides is calculated, and the alkyl epoxides are fed into the secondary reaction unit. After the feeding is completed, the maturation and devolatilization processes are carried out again.

[0035] The polyether intermediate, fed with alkyl epoxides in the primary reactor, is pumped to the stirred tank reactor 7. The multi-layered impeller mechanical agitator 9 and the external circulation pump 11 are then activated sequentially. The material enters the tubular heat exchanger 13. After heat exchange, the material exits the heat exchanger and enters the Venturi nozzle device 10, where it mixes thoroughly with the gas drawn from the top of the stirred tank reactor. The material then exits the Venturi nozzle device and enters the middle of the stirred tank reactor 7. Once the material circulation stabilizes, the alkyl epoxide feed line is opened. Metered alkyl epoxides are sprayed into the reactor from the bottom through atomizing nozzles 8, reacting with the liquid polyether. Unreacted alkyl epoxides rise to the top of the reactor and, through the connecting line 12 between the reactor top and the Venturi nozzle device, are drawn out and enter the Venturi nozzle device 10. After heat exchange with the tubular heat exchanger 13, the material is thoroughly mixed in the Venturi nozzle device 10 and then re-enters the stirred tank reactor 7.

[0036] This invention optimizes the structure of the batch reactor in a two-stage reaction unit. Firstly, epoxides are fed from the bottom of the reactor. Secondly, a Venturi nozzle is installed on the external circulation line of the batch reactor, simultaneously introducing unreacted epoxides from the top of the reactor through the pipeline to the Venturi nozzle for thorough mixing with the liquid material. These structural optimizations ensure efficient mass and heat transfer of the liquid material, especially high-viscosity liquids, within the batch reactor, thereby improving the production efficiency of polyether macromonomers.

[0037] Furthermore, after the polyether intermediate is transferred to the secondary reactor, the primary reactor restarts the next batch of activator initiator feed and epoxide alkane feed, fully utilizing the efficiency of the PRESS reactor in the production of low number-average molecular weight polyethers. The curing and devolatilization processes, or the production processes of high number-average molecular weight polyether macromonomers where the PRESS reactor cannot meet production requirements, are transferred to more suitable batch reactors. This fully leverages the characteristics and performance advantages of different polyether macromonomer reactors.

[0038] In step 3), the polyether intermediate transferred to the secondary reaction unit is subjected to maturation and devolatilization processes under the condition that the designed number-average molecular weight is reached. The maturation temperature is 115±5℃, the maturation pressure is ≤450KPa, and the maturation time is 1.0h; the devolatilization pressure is -0.1MPa, the devolatilization temperature is 80±5℃, and the devolatilization time is 0.5h.

[0039] In step 3), if the polyether intermediate transferred to the secondary reactor does not reach the designed number-average molecular weight, the remaining amount of epoxide to be fed is calculated based on the amount of epoxide already fed, and epoxide feeding continues in the secondary reactor. The reaction temperature in the secondary reactor is 120±5℃, and the reaction pressure is ≤450KPa. After the epoxide feed is completed, a curing and devolatilization process is carried out. The curing temperature is 120±5℃, the curing pressure is ≤450KPa, and the curing time is 1.0h. The devolatilization pressure is -0.1MPa, the devolatilization temperature is 100±5℃, and the devolatilization time is 0.5h.

[0040] In step 3), the secondary reaction unit requires continued feeding of epoxide alkane, which is ethylene oxide only.

[0041] The polyether macromonomer provided by this invention is prepared by the above method. It is colorless or pale yellow, with a number average molecular weight between 2000 and 8000, an effective content of ≥96%, and a double bond retention rate of ≥96%.

[0042] Based on the above description of the equipment, the reaction device system of the present invention comprises a pretreatment vessel, a primary reaction device, and a secondary reaction device, forming a highly efficient preparation system for polyether macromonomers. Figure 3 As shown.

[0043] This invention optimizes the reaction between the initiator and metallic sodium by using a more reactive small-molecule alcohol as an additive. This alcohol reacts with the sodium at the interface between the initiator and metallic sodium, renewing the interface, preventing the accumulation of sodium alkoxide from the initiator, increasing the reaction rate between sodium and the initiator, and shortening the reaction time between sodium and the initiator (especially high-molecular-weight initiators). Furthermore, compared to directly using sodium methoxide as a catalyst, the proportion of sodium methoxide generated in the catalyst is significantly reduced by the method described in this invention, having little impact on the purity of the final polyether macromonomer. During the reaction, the reactivity of the hydroxyl groups of sodium with the initiator decreases with increasing carbon chain length, and the sodium alkoxide generated from the reaction of sodium with the initiator tends to accumulate at the reaction interface, further reducing reaction efficiency. Using methanol, the most reactive additive, as an additive, and continuously adding it dropwise into the reaction system, allows for rapid reaction with sodium, renewing the interface and ensuring the reaction rate between the initiator and metallic sodium.

[0044] The main beneficial effects of this invention are as follows:

[0045] This invention employs the PRESS reactor for the efficient synthesis of low number-average molecular weight polyethers, combined with the mass and heat transfer advantages of a batch reactor for high number-average molecular weight polyethers. The two reactors are connected in series to form a reaction system. Specifically, a PRESS reactor and a batch reactor are connected in series. The PRESS reactor is used for feeding epoxy alkane into polyether macromonomers with a number-average molecular weight ≤3000, while the curing and devolatilization processes, which have lower production efficiency requirements, are transferred to the batch reactor. For polyether macromonomers with a number-average molecular weight >3000, a polyether intermediate is first prepared using the PRESS reactor, and then transferred to the batch reactor for the remaining epoxy alkane feed. The batch reactor's mass and heat transfer advantages under high viscosity conditions are utilized to sequentially complete the remaining epoxy alkane feeding, curing, and devolatilization processes, thus efficiently producing high number-average molecular weight polyether macromonomers. It exhibits good production efficiency for polyether macromonomers with a wide number-average molecular weight range. For number-average molecular weight ≤3000, it is comparable to using a PRESS reactor alone; for number-average molecular weight >3000, it is superior to using a PRESS reactor alone. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the pretreatment device structure; Figure 1 In the diagram, 1 is the rod-shaped sodium metal feeding device, 2 is the rod-shaped sodium metal cage, 3 is the mechanical stirring device, 4 is the initiator inlet, 5 is the small molecule alcohol droplet inlet, and 6 is the batch reactor.

[0047] Figure 2 This is a schematic diagram of the structure of a two-stage reaction apparatus; Figure 2 In the diagram, 7 is a stirred tank reactor, 8 is an atomizing nozzle, 9 is a multi-layered impeller mechanical stirring device, 10 is a Venturi nozzle device, 11 is an external circulation pump, 12 is the connecting pipeline between the reactor top and the Venturi nozzle device, and 13 is a shell-and-tube heat exchanger.

[0048] Figure 3 This is a schematic diagram of the overall reaction device structure of the present invention. Detailed Implementation

[0049] The present invention is described in detail below through examples. These examples are merely illustrative and do not limit the scope of the invention. Based on the disclosure herein, those skilled in the art can make changes to the chemical reagents, processes, and reaction equipment within the scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0050] In this embodiment of the invention, the hydroxyl value and double bond retention rate of the polyether macromonomers were tested according to the methods specified in JC / T2033-2018 "Polyethers and their Derivatives for Concrete Admixtures". The number-average molecular weight of the polyether macromonomers was calculated based on the measured hydroxyl values. The content of each peak of the polyether macromonomers was calculated as an area percentage and determined using a Dalian Elite ichrom 5100 high-performance liquid chromatograph with the following parameters: mobile phase: methanol / water volume ratio 4; mobile phase velocity: 1 ml / min; injection volume: 20 μl; sample concentration: 0.5% (sample g / mobile phase g); detector: differential refractive index detector.

[0051] The examples are divided into three parts: first, the preparation of the activating initiator; second, the preparation of the polyether intermediate; and finally, the preparation of the finished polyether macromonomer. In the examples, "parts" specifically refers to parts by mass, and the amounts of other materials added are all converted to parts by mass.

[0052] I. Preparation of Activating Initiator:

[0053] The active initiator is prepared by reacting an initiator, rod-shaped metallic sodium, and methanol in a pretreatment device. The pretreatment device includes a batch reactor 6, on which a rod-shaped metallic sodium feed device 1 is installed. The rod-shaped metallic sodium feed device 1 is connected to a rod-shaped metallic sodium cage 2 via an elastic structure. The rod-shaped metallic sodium cage 2, a 50cm × 50cm × 50cm stainless steel cage, is used to hold the catalyst rod-shaped metallic sodium, ensuring that the rod-shaped metallic sodium remains submerged below the liquid surface during mechanical stirring. An initiator inlet 4 is provided on the batch reactor for loading the initiator into the reactor. A small molecule alcohol dropwise inlet 5 is provided on the batch reactor for dropwise addition of small molecule alcohols. A mechanical stirring device 3 is installed inside the batch reactor to stir the reaction inside. The initiator is added to the batch reactor 6 through the initiator inlet 4, and the mechanical stirring device 3 is activated to mix thoroughly for 0.5 hours. Rod-shaped sodium metal was loaded into stainless steel sodium metal rod cages 2, with 5-10 rods in each cage, submerged below the surface of the initiator liquid. Then, methanol was added dropwise at a uniform rate through the small molecule alcohol droplet inlet. Under nitrogen protection, the reaction temperature was controlled between 40-70℃, and the reaction time was 3.0-6.0 h, yielding a clear and transparent activated initiator. The material composition of the activated initiator is shown in Table 1.

[0054] Table 1. Material proportions of active initiators (dosage is in parts by mass).

[0055]

[0056] In Table 1, the molar amounts of catalyst used in Q-10 and Q-1 are the same, and the molar amounts of catalyst used in Q-11 and Q-7 are the same.

[0057] II. Preparation of polyether intermediates:

[0058] The activating initiator is transferred to the primary reactor (5th generation PRESS reactor), which is evacuated to -0.1 MPa, then nitrogen is added to bring the pressure back to atmospheric pressure. This process is repeated three times, and the primary reactor is evacuated to -0.1 MPa again. The large and small circulation loops of the primary reactor are started, and the material in the primary reactor is heated to 100°C through heat exchangers on the circulation pipelines. Epoxy alkane feeding begins. Ethylene oxide accounts for 95%-100% of the total epoxy alkane content, while other epoxy alkane components account for 0%-5%. During the epoxy alkane feeding process, the reaction temperature is controlled at 115±5°C, and the reaction pressure is controlled at ≤450 kPa. After the epoxy alkane feeding is completed, the material is directly transferred to the secondary reactor, which has already undergone three nitrogen purgings and is evacuated to -0.1 MPa.

[0059] The molecular weight design data for the polyether intermediates and polyether macromonomers are shown in Table 2. The material ratios for the polyether intermediates in the primary reactor are shown in Table 3.

[0060] Table 2. Number-average molecular weight design of polyether intermediates and polyether macromonomer finished products.

[0061]

[0062]

[0063] Table 3 Material Proportioning Table for Primary Reactor

[0064]

[0065] The process parameters of the polyether intermediate in the primary reaction unit are shown in Table 4.

[0066] Table 4. Process parameters of the first-stage reaction unit

[0067]

[0068]

[0069] As shown in Table 4, the relationship between the molecular weight of the polyether intermediate and the feed rate in the PRESS reactor is non-linear. The feed rate gradually decreases as the molecular weight of the polyether intermediate increases, especially when preparing polyether intermediates with a number average molecular weight greater than 3000, the decrease in feed rate is more significant.

[0070] III. Preparation of polyether macromonomer products:

[0071] The polyether intermediate is transferred from the primary reactor to the secondary reactor, which has undergone three nitrogen purgings and is evacuated to -0.1 MPa. The mechanical agitator and external circulation pump of the secondary reactor are then activated. In the secondary reactor, alkyl epoxides are fed from the bottom of the reactor. The mechanical agitator has multiple layers of impellers. The material is pumped from the bottom pipeline to the Venturi nozzle device via the external circulation pump. It mixes thoroughly with the unreacted alkyl epoxides from the top of the batch reactor in the Venturi nozzle device before re-entering the batch reactor. Specifically: the polyether intermediate, after alkyl epoxide feeding in the primary reactor, is pumped from the primary reactor to the stirred batch reactor 7 in the secondary reactor. The multi-layer impeller mechanical agitator 9 and the external circulation pump 11 are activated sequentially. The material enters the tubular heat exchanger 13. After heat exchange, the material enters the Venturi nozzle device 10 from the heat exchanger outlet. It mixes thoroughly with the gas drawn from the top of the stirred batch reactor in the Venturi nozzle device 10. The material then enters the middle of the stirred batch reactor 7 from the Venturi nozzle device outlet. After the material circulation stabilizes, the epoxy alkane feed line is opened, and the epoxy alkane is fed from the bottom of the reactor. The metered epoxy alkane is sprayed into the reactor from the bottom of the stirred tank reactor through the atomizing nozzle 8 to react with the liquid polyether. The unreacted epoxy alkane rises to the top of the reactor and is led out through the connecting pipeline 12 between the top of the reactor and the Venturi nozzle device, and then enters the Venturi nozzle device 10. After exchanging heat with the tubular heat exchanger 13, the material is fully mixed in the Venturi nozzle device 10 and then enters the stirred tank reactor 7 again.

[0072] For polyether intermediates that have reached the designed number-average molecular weight, the polyether macromonomer is obtained after curing and devolatilization processes. The curing temperature is 115±5℃, the curing pressure is ≤450KPa, and the curing time is 1.0h. After curing, a devolatilization process is carried out at a temperature of 80±5℃, a devolatilization pressure of -0.1MPa, and a devolatilization time of 0.5h.

[0073] For polyether intermediates that do not reach the designed number-average molecular weight, the amount of remaining unfeeded epoxides is calculated. The remaining epoxides are fed under the conditions of a reaction temperature of 120±5℃ and a reaction pressure ≤450KPa. After the epoxide feeding is completed, the product enters the curing and devolatilization process. The curing temperature is 120±5℃, the curing pressure is ≤450KPa, and the curing time is 1.0h; the devolatilization pressure is -0.1MPa, the devolatilization temperature is 100±5℃, and the devolatilization time is 0.5h. Specific parameters are shown in Table 5.

[0074] Table 5. Epoxyalkane dosage and process parameters in the secondary reaction unit

[0075]

[0076]

[0077] As can be seen from the data in Tables 4 and 5, the system using the two-stage reaction apparatus described in this invention has a similar total feed time for epoxides with a number-average molecular weight ≤3000 to the comparative example using a PRESS reactor alone. For the polyether macromonomers with a number-average molecular weight >3000, the total feed time for epoxides is shortened by more than 1.0 h compared to the comparative example using a PRESS reactor alone. This indicates that the polyether macromonomer preparation system described in this invention is more advantageous for the production of polyether macromonomers with high number-average molecular weights and can significantly save production energy consumption.

[0078] The hydroxyl value, number-average molecular weight, double bond retention rate, and effective content of the polyether macromonomer product described in this invention were all tested, and the test results are shown in Table 6.

[0079] Table 6. Analysis and Testing of Polyether Macromonomer Finished Products

[0080]

[0081]

[0082] As shown in Table 6, the system constructed using the two-stage reaction apparatus described in this invention exhibits relatively normal hydroxyl value, number-average molecular weight, double bond retention rate, and effective content of the polyether macromonomers. The polyether macromonomers prepared using the activating initiator described in this invention demonstrate better hydroxyl value, number-average molecular weight, double bond retention rate, and effective content compared to those prepared using sodium methoxide as a catalyst.

Claims

1. A process for the preparation of a polyether macromonomer, characterized in that, The preparation method Includes the following steps: A method for preparing a polyether macromonomer includes the following steps: 1) Mix the initiator, small molecule alcohol, and catalyst, and react until a clear solution is obtained to obtain the activated initiator; 2) The activating initiator is transferred to a primary reaction apparatus, and epoxy alkane is introduced to obtain a polyether intermediate; 3) The polyether intermediate is transferred to a secondary reaction unit to prepare the polyether macromonomer; In step 1), the small molecule alcohol is selected from methanol and is continuously added dropwise into the reaction system of step 1); the amount of the small molecule alcohol is 10%-30% of the catalyst mass. In step 1), the initiator is selected from allyl alcohol, methyl allyl alcohol, 3-methyl-3-buten-1-ol, 4-methyl-4-penten-1-ol, 7-octen-1-ol, 3,7-dimethyl-7-octen-1-ol, 10-undecenol, isoprene alcohol, ethylene glycol monovinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutylvinyl ether unsaturated alcohol; the catalyst is selected from sodium metal. In step 2), the primary reaction device is a PRESS reactor; In step 3), the polyether intermediate transferred to the secondary reaction unit is subjected to curing and devolatilization processes under the condition that the designed number-average molecular weight is reached. The curing temperature is 115±5℃, the curing pressure is ≤450KPa, and the curing time is 1.0h; the devolatilization pressure is -0.1MPa, the devolatilization temperature is 80±5℃, and the devolatilization time is 0.5h. Alternatively, in step 3), if the polyether intermediate transferred to the secondary reaction unit does not reach the designed number-average molecular weight, alkyl epoxides are continued to be fed into the secondary reaction unit. The reaction temperature of the secondary reaction unit is 120±5℃, and the reaction pressure is ≤450KPa. After the alkyl epoxide feed is completed, a curing and devolatilization process is carried out. The curing temperature is 120±5℃, the curing pressure is ≤450KPa, and the curing time is 1.0h. The devolatilization pressure is -0.1MPa, the devolatilization temperature is 100±5℃, and the devolatilization time is 0.5h.

2. The production method according to claim 1, characterized by, In step 1), the catalyst is always below the liquid level in the reaction system of step 1).

3. The preparation method according to claim 1, characterized in that, In step 1), the reaction is carried out at a temperature between 40-70°C for 3.0-6.0 hours.

4. The method of claim 1, wherein, In step 2), the reaction temperature is 115±5℃ and the reaction pressure is ≤450Kpa.

5. The preparation method according to claim 1, characterized in that, In step 3), the secondary reaction device is a stirred tank reactor in which epoxide alkane is fed from the bottom of the reactor.

6. A polyether macromonomer prepared by the preparation method according to any one of claims 1-5, characterized in that, The polyether macromonomers have a number-average molecular weight between 2000 and 8000, an effective content of ≥96%, and a double bond retention rate of ≥96%.

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