Process for the continuous production of chlorohydrin rubber

Abstract

This application provides a method for the continuous preparation of chlorohydrin rubber, belonging to the field of rubber manufacturing. The method involves continuously feeding toluene, monomers, and a catalyst into a pipeline reactor, controlling the reaction temperature for continuous polymerization. After the reaction is complete, a terminator is added to obtain a chlorohydrin rubber reaction solution. This solution is then fed into a first horizontal biaxial kneading devolatilizer for a first vacuum devolatilization process, achieving a solid content of 65-85% to obtain quasi-solid chlorohydrin rubber. The quasi-solid chlorohydrin rubber is then fed into a second horizontal biaxial kneading devolatilizer for a second vacuum devolatilization process. Moisture is added during this process, and the material temperature is controlled to not exceed 100°C in the later stages of devolatilization. After devolatilization, the material is discharged and cut to obtain devolatilized rubber granules, which are then extruded, metered, and packaged to obtain the finished chlorohydrin rubber product. This application achieves precise temperature control and a narrow molecular weight distribution through the synergy of the pipeline reactor and the two-stage devolatilizer, reducing toluene residue and gel content in the product, resulting in stable Mooney viscosity and excellent batch-to-batch consistency.

Description

Technical Field

[0001] This invention relates to the field of rubber manufacturing technology, and more specifically to a method for the continuous preparation of chlorohydrin rubber. Background Technology

[0002] Chlorohydrin rubber is produced by homopolymerization of epichlorohydrin or copolymerization with ethylene oxide, propylene oxide, etc., using anionic coordination polymerization process with alkyl aluminum-water / alcohol as a catalyst, polymerizing at low temperature in toluene, followed by termination, devolatilization, and drying to obtain the finished product. This rubber is oil-resistant, acid and alkali-resistant, temperature-resistant, has low air permeability, is ozone-resistant, and flame-retardant. It has good adhesion to metals and fabrics, and its performance is superior to nitrile rubber and chloroprene rubber under harsh working conditions involving oil, water, and chemical media. It is widely used in the automotive, petrochemical, hydraulic sealing, and electronic cable industries, and is a core material for high-end seals and hoses.

[0003] Currently, the industrial production of chlorohydrin rubber mainly involves two steps: First, polymerization is carried out in a batch reactor, with toluene, monomer, and catalyst added in proportion, and a terminator added after a certain reaction time; Second, a combination of water-toluene azeotropic batch devolatilization and static drying in an oven is used, where toluene is evaporated under normal pressure and the rubber solution is coagulated, then water is removed by a vibrating screen and transferred to a hot air oven for long-term drying to obtain the finished product. This traditional batch process has many problems: the operation steps are lengthy and the reaction efficiency is low; the polymerization conversion rate must be controlled at a low level, and the heat of reaction is difficult to remove; the devolatilization process consumes a large amount of water, resulting in high evaporation energy consumption, and if water is recycled, energy consumption will be further increased; if it is not recycled, a large amount of solvent-containing wastewater will be generated, resulting in high environmental costs.

[0004] Due to the viscosity-increasing and high-viscosity characteristics of polymerization reactions, the requirements for mass and heat transfer equipment are extremely high. Conventional reactors, such as screw reactors and horizontal disc reactors, typically rely on enhanced stirring, but their heat transfer capacity is limited. Existing devolatilization devices, such as azeotropic distillation kettles, screw devolatilizers, and high-temperature atomizers, are all insufficient to meet the full devolatilization requirements of chlorohydrin rubber from low-viscosity liquid to high-viscosity solids. Therefore, developing a continuous, efficient, and low-energy-consumption process for the preparation of chlorohydrin rubber is of great significance.

[0005] In view of this, it is necessary to design a method for the continuous preparation of chlorohydrin rubber to solve the above problems. Summary of the Invention

[0006] In view of the technical problems existing in the background art, this application provides a method for continuous preparation of chlorohydrin rubber, which aims to solve the technical problems of low efficiency, low production capacity and high energy consumption in the preparation process of existing chlorohydrin rubber.

[0007] This application provides a method for the continuous preparation of chlorohydrin rubber, comprising the following steps: S1. Toluene, monomer and catalyst are continuously fed into a pipeline reactor, and the reaction temperature is controlled to carry out a continuous polymerization reaction. After the reaction is completed, a terminator is added to obtain a chlorohydrin rubber reaction solution. S2. The chlorohydrin rubber reaction solution is fed into the first horizontal twin-shaft kneading devolatilizer for the first vacuum devolatilization, so that the solid content of the material reaches 65~85% and quasi-solid chlorohydrin rubber is obtained. S3. The quasi-solid chlorohydrin rubber is fed into the second horizontal twin-shaft kneading devolatilizer for a second vacuum devolatilization. Moisture is added during the devolatilization process, and the material temperature is controlled to not exceed 100°C in the later stage of devolatilization. After the devolatilization is completed, the material is discharged and cut to obtain the devolatilized rubber granules. S4. The devolatilized rubber particles are extruded, measured, and packaged to obtain the finished chlorohydrin rubber product.

[0008] As a further improvement of this application, in step S1, the pipeline reactor includes three temperature control zones and one cooling zone, wherein the temperatures of the three temperature control zones are: the polymerization temperature of the front section is 40~60℃, the polymerization temperature of the middle section is 60~80℃, and the polymerization temperature of the rear section is 80~120℃.

[0009] As a further improvement of this application, in step S1, the feed mass ratio of toluene, monomer and catalyst is (1~9):1:(0.001~0.05).

[0010] As a further improvement to this application, the monomer is one or more of epichlorohydrin, ethylene oxide, and propylene oxide.

[0011] As a further improvement of this application, in step S1, the residence time of the material in the pipeline reactor is 0.5~2h.

[0012] As a further improvement of this application, in step S2, the vacuum degree in the first horizontal biaxial kneading devolatilizer is -85~-95kPa, and the devolatilization temperature is 60~100℃.

[0013] As a further improvement of this application, the stirring speed of the main motor of the first horizontal twin-shaft kneading and de-wiring machine is 3~15 r / min, and the stirring speed of the auxiliary motor is 10~100 r / min.

[0014] As a further improvement of this application, in step S3, the vacuum degree inside the second horizontal biaxial kneading devolatilizer is -95~-99kPa, and the devolatilization temperature is 90~120℃.

[0015] As a further improvement of this application, the main motor of the second horizontal twin-shaft kneading and de-wiring machine has a stirring speed of 20~40 r / min, and the auxiliary motor has a stirring speed of 10~100 r / min.

[0016] As a further improvement of this application, in step S3, the second horizontal biaxial kneading and de-waxing machine is divided into three chambers, and the water replenishment flow rate of each chamber is independently 0.5~1.5kg / h.

[0017] The beneficial effects of this application are as follows: This application provides a method for the continuous preparation of chlorohydrin rubber. Toluene, monomers, and a catalyst are continuously fed into a pipeline reactor, and the reaction temperature is controlled to carry out the polymerization reaction. After the reaction is completed, a terminator is added to obtain a chlorohydrin rubber reaction solution. The chlorohydrin rubber reaction solution is then fed into a first horizontal biaxial kneading devolatilizer for a first vacuum devolatilization, bringing the solid content of the material to 65-85%, resulting in quasi-solid chlorohydrin rubber. The quasi-solid chlorohydrin rubber is then fed into a second horizontal biaxial kneading devolatilizer for a second vacuum devolatilization. Moisture is added during the devolatilization process, and the material temperature is controlled to not exceed 100°C in the later stage of devolatilization. After devolatilization, the material is discharged and cut to obtain devolatilized rubber granules. The devolatilized rubber granules are then extruded, metered, and packaged to obtain the finished chlorohydrin rubber product. This application achieves precise temperature control and a narrow molecular weight distribution in the polymerization reaction through the synergistic combination of a pipeline reactor and a two-stage horizontal biaxial kneading devolatilizer. Simultaneously, the active cooling design in the later stage of the two-stage devolatilizer effectively avoids overheating degradation of high-viscosity materials due to viscosity dissipation. This process significantly reduces the residual toluene and gel content in the product, resulting in stable Mooney viscosity and excellent batch-to-batch consistency. Compared to existing technologies, this process significantly reduces energy consumption and wastewater discharge, making it a highly efficient, environmentally friendly method suitable for continuous industrial production of chlorohydrin rubber.

[0018] Compared to batch polymerization, the continuous tubular polymerization process provided in this application has a narrower molecular weight distribution, more uniform Mooney viscosity, higher batch stability, fewer side reactions, and lower impurities. Production is continuous and efficient, with a larger heat exchange area per unit volume, allowing for timely removal of reaction heat and avoiding the risks of localized overheating and explosive polymerization. The process is safer, with a fully closed system reducing solvent evaporation and VOC emissions, resulting in better safety and environmental friendliness, and is easily automated.

[0019] Traditional azeotropic distillation devolatilization kettles operate intermittently, requiring batch operations, resulting in long operating times, limited capacity, and material loss and contamination during batch switching. In contrast, the two-stage biaxial kneading devolatilization machine in this application adopts a continuous process. Through forced kneading and pushing by two axes, combined with two-stage gradient devolatilization, it can achieve large-scale production capacity, with production efficiency 3 to 5 times higher than that of azeotropic kettles, making it suitable for the capacity requirements of continuous production lines in the chlorohydrin rubber industry.

[0020] This application achieves more thorough devolatilization with lower volatile residue. Traditional azeotropic distillation relies on the water-toluene azeotropic principle to remove solvents, achieving only 60%–80% solvent removal rate. Furthermore, small volatile molecules within the rubber particles are difficult to diffuse to the surface, requiring prolonged oven drying. This application utilizes a two-stage biaxial kneading devolatilization machine. Through the strong shearing and kneading action of the biaxial shafts, the rubber compound is dispersed into a thin film, providing high-frequency surface renewal, increasing the diffusion area of ​​volatiles, and eliminating the need for an additional drying process. Uniform heating throughout the drum ensures more even and efficient devolatilization, while also protecting the finished rubber product from overheating and deterioration.

[0021] This application significantly reduces energy consumption and environmental pressure. Traditional azeotropic devolatilization requires a large amount of deionized water, resulting in high energy consumption; at the same time, the solvent-containing wastewater generated after condensation requires additional treatment, leading to high environmental costs. The two-stage biaxial kneading devolatilization machine of this application requires only a very small amount of azeotropic agent, and the solvent vapor generated during devolatilization can be directly recycled after condensation and water separation, significantly reducing environmental treatment pressure. The process flow of this application is simpler, and it can directly process low-solids content rubber solutions after polymerization, and effectively remove the heat generated by extrusion friction in the later high-solids content stage, avoiding local overheating and degradation of chlorohydrin rubber, and directly obtaining qualified rubber particles after devolatilization.

[0022] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0024] Figure 1 A schematic flowchart of a method for the continuous preparation of chlorohydrin rubber provided in this application embodiment; Explanation of reference numerals in the attached drawings: 1. Toluene feed pump; 2. Monomer feed pump; 3. Catalyst feed pump; 4. Terminator feed pump; 5. Pipeline reactor; 6. First horizontal twin-shaft kneading and devolatilization machine; 7. Main motor of the first horizontal twin-shaft kneading and devolatilization machine; 8. Auxiliary motor of the first horizontal twin-shaft kneading and devolatilization machine; 9. Second horizontal twin-shaft kneading and devolatilization machine; 10. Main motor of the second horizontal twin-shaft kneading and devolatilization machine; 11. Auxiliary motor of the second horizontal twin-shaft kneading and devolatilization machine; 12. First condenser; 13. First recovery tank; 14. First vacuum pump; 15. Second condenser; 16. Second recovery tank; 17. Second vacuum pump. Detailed Implementation

[0025] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0027] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0029] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0030] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0031] Existing chlorohydrin rubber production processes suffer from two main drawbacks: polymerization and devolatilization. The polymerization process often employs conventional batch reactors, which suffer from lengthy operation, low efficiency, difficulty in removing heat of reaction, and limited conversion rates. Furthermore, traditional stirred reactors are insufficient to meet the heat transfer requirements of high-viscosity to high-viscosity systems. The devolatilization process relies on a combination of water-toluene azeotropic distillation and static oven drying, which not only consumes a large amount of water and energy and incurs high costs for wastewater treatment, but also suffers from poor adaptability to existing continuous devolatilization technologies such as falling film, screw, and atomization. These technologies present challenges such as easy material cross-contamination in the early stages when the solid content is low, difficulty in surface renewal in the later stages when the viscosity is high, difficulty in controlling the consistency of long tube-pass components, and easy nozzle clogging and polymer entrainment loss in atomization. These issues make it difficult to achieve efficient, energy-saving, large-scale continuous production.

[0032] To address the technical problems of low efficiency, low production capacity, and high energy consumption in the preparation of existing chlorohydrin rubber, this application provides a method for the continuous preparation of chlorohydrin rubber. In this method, a pipeline reactor is used as the polymerization reactor, and a two-stage horizontal biaxial kneading devolatilizer is used as the devolatilization device. Based on the characteristics of chlorohydrin rubber, a qualified product with stable and uniform quality and low residual volatile matter is obtained through process optimization.

[0033] Please refer to Figure 1 This application provides a method for the continuous preparation of chlorohydrin rubber, comprising the following steps: S1. Toluene, monomer and catalyst are continuously fed into pipeline reactor 5, and the reaction temperature is controlled to carry out continuous polymerization. After the reaction is completed, a terminator is added to obtain chlorohydrin rubber reaction solution.

[0034] Specifically, the pipeline reactor 5 has four independent jackets and internal coils. The first three sections control the reaction temperature, while the last section cools down the reaction. A turbulence-inducing structure is installed inside the tubes to enhance the flowability of highly viscous materials and increase mixing efficiency. After vacuum treatment and complete nitrogen purging of the pipeline reactor 5 and the devolatilization system, toluene, monomer, and catalyst are injected into the pipeline reactor 5 at specific ratios and flow rates using a high-pressure horizontal flow pump. The residence time and conversion rate can be adjusted in a timely manner by regulating the flow rate and ratio. The temperature control system of the pipeline reactor 5 is then activated to control the reaction temperature in the three sections. The temperature control system achieves temperature control by adjusting the temperature of the heat transfer medium in the outer jacket and inner coil of each section. As the reaction proceeds, the reaction liquid gradually becomes more viscous, making it difficult to achieve turbulence in the later stages. Therefore, multiple turbulence-inducing structures are installed inside the pipeline reactor 5 to enhance the reaction mass and heat transfer effects. A terminator is injected at the end of the third section of the pipeline reactor 5 using a horizontal flow pump to terminate the reaction.

[0035] S2. The chlorohydrin rubber reaction solution is fed into the first horizontal twin-shaft kneading and devouring machine 6 for the first vacuum devouring, so that the solid content of the material reaches 65~85%, and quasi-solid chlorohydrin rubber is obtained.

[0036] Specifically, when the chlorohydrin rubber reaction solution reaches the first horizontal biaxial kneading and devolatilization machine 6, the vacuum system is activated, the vacuum level is adjusted, and the three independent temperature control systems of the first horizontal biaxial kneading and devolatilization machine 6 are adjusted to reach the predetermined temperature. The main motor agitation is then activated. The main motor agitation not only exerts strong pulling and shearing forces on the rubber solution radially, but also has a certain forward pushing force axially. When the chlorohydrin rubber changes from a fluid state to a quasi-solid state in the latter part of the first horizontal biaxial kneading and devolatilization machine 6, the auxiliary motor twin-shaft screw discharge agitation is activated to send the quasi-solid chlorohydrin rubber to the second horizontal biaxial kneading and devolatilization machine 9.

[0037] S3. The quasi-solid chlorohydrin rubber is fed into the second horizontal twin-shaft kneading devolatilizer 9 for a second vacuum devolatilization. Moisture is added during the devolatilization process, and the material temperature is controlled to not exceed 100°C in the later stage of devolatilization. After the devolatilization is completed, the material is discharged and cut to obtain devolatilized rubber granules.

[0038] Specifically, both the first horizontal bi-shaft kneading and devolatilization machine 6 and the second horizontal bi-shaft kneading and devolatilization machine 9 are three-section jacketed chambers connected in series. Each of the three jacketed chambers is equipped with a sight glass for easy observation of the state of the chloroprene rubber inside each chamber. The three chambers of the first horizontal bi-shaft kneading and devolatilization machine 6 have independent heating systems, while the three chambers of the second horizontal bi-shaft kneading and devolatilization machine 9 have an integrated heating and cooling system. The bi-shaft kneading and devolatilization machine has a horizontal figure-eight cylindrical structure, allowing the stirring paddle to reach the rubber solution on every part of the cylinder wall. Internally, there are two sets of screws rotating in the same or opposite directions and meshing with each other. Kneading elements are installed on the shafts at a certain angle, providing functions of pulling, squeezing, self-cleaning, and propelling the material forward. Both the main motor and the auxiliary motor are variable frequency motors, allowing for easier adjustment of process parameters.

[0039] The feed inlet of the first horizontal twin-shaft kneading and degassing machine 6 is connected to the outlet of the pipeline reactor 5. The middle and rear sections are equipped with air outlets, which are connected in parallel to the first condenser 12, the first recovery tank 13 and the first vacuum pump 14 in sequence. The twin-shaft discharge spiral of the first horizontal twin-shaft kneading and degassing machine 6 is perpendicular to the main stirrer and located at the tail end of the main stirrer. Its discharge port is directly connected to the feed inlet of the second horizontal twin-shaft kneading and degassing machine 9.

[0040] The second horizontal twin-shaft kneading and degassing machine 9 has air outlets in the front, middle and rear sections, which are connected in parallel to the second condenser 15, the second recovery tank 16 and the second vacuum pump 17 in sequence; the twin-shaft discharge screw of the second horizontal twin-shaft kneading and degassing machine 9 is also perpendicular to the main mixer and located at the tail end of the main mixer.

[0041] When the quasi-solid chlorohydrin rubber enters the second horizontal bishaft kneading and devolatilizing mill 9 and fills the discharge screw of the first horizontal bishaft kneading and devolatilizing mill 6, the vacuum degree of the second horizontal bishaft kneading and devolatilizing mill 9 is increased, and the main motor of the second horizontal bishaft kneading and devolatilizing mill 9 is turned on to stir. As the chlorohydrin rubber moves forward, the water replenishment system in each chamber is turned on in sequence, and a small amount of water is added quantitatively using a metering pump. This not only reduces the situation of local compression friction overheating, but also enhances the removal of toluene by azeotropic reaction with toluene. When the chlorohydrin rubber reaches the rear section of the second horizontal bishaft kneading and devolatilizing mill 9, the solid content is already very high. At this time, no additional heating is required. The compression of the chlorohydrin rubber by the main motor stirring and the friction of the chlorohydrin rubber on the cylinder will generate a lot of heat. The heat is removed by the independent temperature control system in the rear section, which can prevent heat runaway and increase the degradation of chlorohydrin rubber, thus affecting product quality. When the chlorohydrin rubber has finished devolatilization and enters the discharge channel, the auxiliary motor of the second horizontal twin-shaft kneading devolatilizer 9 is turned on to stir the chlorohydrin rubber into small spherical transparent rubber particles and transport them outside the devolatilization system.

[0042] S4. The devolatilized rubber particles are extruded, measured, and packaged to obtain the finished chlorohydrin rubber product.

[0043] Furthermore, in some embodiments, in step S1, the pipeline reactor 5 includes three temperature control zones and one cooling zone, wherein the temperatures of the three temperature control zones are: the front polymerization temperature is 40~60℃, the middle polymerization temperature is 60~80℃, and the rear polymerization temperature is 80~120℃.

[0044] In the technical solution of this application embodiment, the reaction is initiated at a low temperature in the early stage to control the chain growth rate and avoid explosive polymerization. In the middle stage, the temperature is gradually increased to improve the monomer conversion rate. In the later stage, the high temperature promotes the deep polymerization of residual monomers. At the same time, the temperature of the reaction solution is rapidly reduced by the final stage cooling to suppress side reactions and match the feed requirements of the devolatilization process. High conversion rate is achieved while ensuring safety and uniform molecular weight distribution. The chlorohydrin rubber reaction solution from the pipeline reactor 5 directly enters the two-stage biaxial devolatilization system.

[0045] Furthermore, in some embodiments, in step S1, the feed mass ratio of toluene, monomer, and catalyst is (1~9):1:(0.001~0.05). The monomer is one or more of epichlorohydrin, ethylene oxide, and propylene oxide.

[0046] In the technical solution of this application embodiment, the concentration and viscosity of the reaction system are balanced by adjusting the ratio of toluene to monomer, which helps to achieve good mass and heat transfer and plug flow characteristics in the early stage of polymerization. At the same time, the amount of catalyst is controlled within an appropriate range to maintain a mild anionic coordination polymerization rate, avoid local overheating and explosive polymerization, and achieve continuous and stable operation with high conversion rate and narrow molecular weight distribution in the pipeline reactor 5. Specifically, the catalyst is preferably a ternary catalytic system composed of triisobutylaluminum, phosphoric acid and aniline.

[0047] Furthermore, in some embodiments, in step S1, the residence time of the material in the pipeline reactor 5 is 0.5~2h.

[0048] In the technical solution of this application embodiment, the material residence time and the three-stage temperature control gradient of the pipeline reactor 5 work together to allow the monomer to undergo low-temperature initiation growth and medium-high temperature deep polymerization stages in sequence under plug flow conditions, so as to achieve full conversion and prevent the molecular weight distribution from becoming wider or side reactions from being aggravated due to excessive time. At the same time, it is matched with the final cooling stage so that the reaction liquid is reduced to a suitable devolatilization temperature before discharge, thereby achieving a balance between high conversion rate and narrow distribution.

[0049] Furthermore, in some embodiments, in step S2, the vacuum degree inside the first horizontal biaxial kneading and devolatilizing machine 6 is -85~-95 kPa, and the devolatilization temperature is 60~100℃. The stirring speed of the main motor 7 of the first horizontal biaxial kneading and devolatilizing machine is 3~15 r / min, and the stirring speed of the auxiliary motor 8 of the first horizontal biaxial kneading and devolatilizing machine is 10~100 r / min.

[0050] In the technical solution of this application embodiment, the boiling points of toluene and water are significantly reduced by high vacuum, and gentle heating is used to promote the efficient release of volatiles; the main motor provides strong shearing and axial pushing at low speed, avoiding material flow while the material is still fluid and continuously renewing the surface to diffuse small molecules; the auxiliary motor acts at high speed on the thickened quasi-solid material in the later stage, forcibly crushing, kneading and extruding forward, thereby removing solvent in a gradient under the synergistic effect of two-stage shearing, accurately controlling the solid content to 65%~85%, and preparing a stable feed for the secondary devolatilization.

[0051] Furthermore, in some embodiments, in step S3, the vacuum degree inside the second horizontal biaxial kneading and devolatilization machine 9 is -95 to -99 kPa, and the devolatilization temperature is 90 to 120°C. The stirring speed of the main motor 10 of the second horizontal biaxial kneading and devolatilization machine is 20 to 40 r / min, and the stirring speed of the auxiliary motor 11 of the second horizontal biaxial kneading and devolatilization machine is 10 to 100 r / min.

[0052] In the technical solution of this application embodiment, the second vacuum devolatilization significantly reduces the equilibrium partial pressure of residual toluene and water under high vacuum and higher temperature, forcing deep volatiles to escape rapidly; the main motor applies strong shearing and kneading to the quasi-solid rubber compound at a high speed, realizing continuous surface renewal to shorten the diffusion path, while using the viscous dissipation generated by strong shearing to heat the interior of the rubber compound, promoting the migration of toluene from the core to the surface; the auxiliary motor cuts the completely devolatilized rubber compound into uniform rubber particles at the end and outputs them, thereby directly obtaining a qualified product with a toluene residue of ≤0.1% without subsequent drying process.

[0053] Furthermore, in some embodiments, in step S3, the second horizontal biaxial kneading and de-waxing machine is divided into three chambers, and the water replenishment flow rate of each chamber is independently 0.5~1.5 kg / h.

[0054] In the technical solution of this application embodiment, the amount of water added to each chamber is precisely controlled according to the gradient difference of residual toluene content and the degree of frictional heat generation in the material before, during and after the devolatilization. The azeotropic desorption in the front section helps to quickly reduce high concentrations of toluene, the azeotropic desorption in the middle section maintains the desorption and alleviates shear heat, and the micro-water addition in the rear section prevents the surface of the rubber particles from becoming too dry and sticking together. Thus, while enhancing the efficiency of toluene removal, excessive water is avoided to prevent energy consumption from increasing or the rubber from hydrolyzing, achieving a balance between low residue and high yield.

[0055] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0056] Example 1 This application provides a method for the continuous preparation of chlorohydrin rubber, comprising the following steps: S1. After vacuum treatment and full nitrogen purging of the entire reaction and devolatilization system, the reactants are pumped into the pipeline reactor 5 via toluene feed pump 1, monomer feed pump 2, and catalyst feed pump 3. The toluene flow rate is 270 kg / h, the epichlorohydrin flow rate is 30 kg / h, and the catalyst flow rate (triisobutylaluminum, phosphoric acid, and aniline in a mass ratio of 60:120:9) is 150 g / h. The temperature control system of the pipeline reactor 5 is then activated, controlling the three reaction temperatures to 60℃, 80℃, and 120℃ respectively. The residence time of the materials in the pipeline reactor 5 is controlled to 1 hour. At the end of the third stage of the pipeline reactor 5, a terminator feed pump 4 is used to inject a terminator to terminate the reaction. The terminator is 10... A toluene solution of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] by weight (wt%), wherein the amount of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] by weight is 1% of the monomer mass, and the flow rate of the terminator solution is 3 kg / h; the last section of the pipeline reactor 5 is a cooling section, which cools the chlorohydrin rubber reaction solution to the predetermined devolatilization temperature of 80°C, and the outlet of the pipeline reactor 5 is directly connected to the inlet of the two-stage biaxial devolatilization system; S2. When the chlorohydrin rubber reaction solution reaches the first horizontal twin-shaft kneading and devolatilization machine 6, the vacuum system is turned on, the vacuum degree is adjusted to -90kPa, and the temperatures of the three independent temperature control systems of the first horizontal twin-shaft kneading and devolatilization machine 6 are adjusted to 80℃ for the front section, 90℃ for the middle section, and 100℃ for the rear section. The main motor 7 of the first horizontal twin-shaft kneading and devolatilization machine is turned on to stir, and the speed is set to 10r / min. When the chlorohydrin rubber reaches the rear section of the first horizontal twin-shaft kneading and devolatilization machine 6 and changes from a fluid state to a quasi-solid state, that is, when the solid content of the material reaches 75%, the auxiliary motor 8 of the first horizontal twin-shaft kneading and devolatilization machine is turned on, and the speed is set to 25r / min. The quasi-solid chlorohydrin rubber is then transported to the second horizontal twin-shaft kneading and devolatilization machine 9. S3. Quasi-solid chlorohydrin rubber enters the second horizontal biaxial kneading and devolatilization machine 9, filling the discharge screw of the first horizontal biaxial kneading and devolatilization machine 6. The vacuum degree of the second horizontal biaxial kneading and devolatilization machine 9 is then raised to -98 kPa. The main motor 10 of the second horizontal biaxial kneading and devolatilization machine is turned on to stir at a speed of 30 r / min. As the chlorohydrin rubber advances within the second horizontal biaxial kneading and devolatilization machine 9, the water replenishment systems of each chamber are activated sequentially. A metering pump is used to quantitatively replenish water: 1.5 kg / h for the front chamber, 1.0 kg / h for the middle chamber, and 0.5 kg / h for the rear chamber. h; The temperature of each section of the second horizontal twin-shaft kneading devolatilizer 9 is controlled at 100℃; To prevent heat accumulation leading to overheating and degradation of the material, the independent temperature control system of the rear chamber of the second horizontal twin-shaft kneading devolatilizer 9 is switched to cooling mode, and a 25℃ cooling medium is introduced into the jacket to actively remove the heat generated by friction, keeping the temperature of the material in the rear section below 100℃ to avoid temperature runaway; When the chlorohydrin rubber devolatilization is completed and enters the discharge channel, the auxiliary motor 11 of the second horizontal twin-shaft kneading devolatilizer is turned on, and the speed is set to 25r / min to cut the devolatilized chlorohydrin rubber into small spherical transparent rubber particles and convey them out of the devolatilization system; S4. The devolatilized rubber granules are extruded, metered, and packaged to obtain the finished chlorohydrin rubber. The toluene residue in the chlorohydrin rubber was found to be 0.1% by headspace gas chromatography, and the Mooney viscosity ML(1+4) at 100℃ was 54, which meets the product quality requirements.

[0057] Example 2 This application provides a method for the continuous preparation of chlorohydrin rubber, comprising the following steps: S1. After vacuum treatment and full nitrogen replacement of the entire reaction and devolatilization system, the reaction raw materials are pumped into the pipeline reactor 5 via toluene feed pump 1, monomer feed pump 2, and catalyst feed pump 3, respectively. The toluene flow rate is 240 kg / h, the epichlorohydrin and ethylene oxide (mass ratio of epichlorohydrin to ethylene oxide is 2:1) flow rate is 60 kg / h, and the catalyst (mass ratio of triisobutylaluminum, phosphoric acid, and aniline is 50:140:12) flow rate is 200 g / h. The temperature control system of the pipeline reactor 5 is then activated, controlling the three reaction temperatures to 40℃, 60℃, and 80℃, respectively. The residence time of the materials in the pipeline reactor 5 is controlled to 1 h. At the end of the third stage of the pipeline reactor 5, a terminator feed pump 4 is used to inject a terminator to terminate the reaction. The terminator is 10... A toluene solution of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] by weight (wt%), wherein the amount of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] by weight is 1% of the monomer mass, and the flow rate of the terminator solution is 6 kg / h; the last section of the pipeline reactor 5 is a cooling section, which cools the chlorohydrin rubber reaction solution to the predetermined devolatilization temperature of 60°C, and the outlet of the pipeline reactor 5 is directly connected to the inlet of the two-stage biaxial devolatilization system; S2. When the chlorohydrin rubber reaction solution reaches the first horizontal twin-shaft kneading and devolatilization machine 6, the vacuum system is turned on, the vacuum degree is adjusted to -90kPa, and the temperatures of the three independent temperature control systems of the first horizontal twin-shaft kneading and devolatilization machine 6 are adjusted to 60℃ for the front section, 90℃ for the middle section, and 100℃ for the rear section. The main motor 7 of the first horizontal twin-shaft kneading and devolatilization machine is turned on to stir, and the speed is set to 15r / min. When the chlorohydrin rubber changes from a fluid state to a quasi-solid state in the rear section of the first horizontal twin-shaft kneading and devolatilization machine 6, the solid content of the material reaches 75%. The auxiliary motor 8 of the first horizontal twin-shaft kneading and devolatilization machine is turned on, and the speed is set to 30r / min to transport the quasi-solid chlorohydrin rubber to the second horizontal twin-shaft kneading and devolatilization machine 9. S3. Quasi-solid chlorohydrin rubber enters the second horizontal biaxial kneading and devolatilization machine 9, and after filling the discharge screw of the first horizontal biaxial kneading and devolatilization machine 6, the vacuum degree of the second horizontal biaxial kneading and devolatilization machine 9 is raised to -99 kPa; the main motor 10 of the second horizontal biaxial kneading and devolatilization machine is turned on for stirring, and the speed is set to 30 r / min. As the chlorohydrin rubber moves forward in the second horizontal biaxial kneading and devolatilization machine 9, the water replenishment system of each chamber is turned on in sequence, and water is replenished quantitatively using a metering pump: the water replenishment rate of the first chamber is 1.5 kg / h, the water replenishment rate of the middle chamber is 1.0 kg / h, and the water replenishment rate of the last chamber is 0.5 kg / h. h; The temperature of each section of the second horizontal twin-shaft kneading devolatilizer 9 is controlled at 100℃; To prevent heat accumulation leading to overheating and degradation of the material, the independent temperature control system of the rear chamber of the second horizontal twin-shaft kneading devolatilizer 9 is switched to cooling mode, and a 25℃ cooling medium is introduced into the jacket to actively remove the heat generated by friction, keeping the temperature of the rear material below 100℃ to avoid temperature runaway; When the chlorohydrin rubber devolatilization is completed and enters the discharge channel, the auxiliary motor 11 of the second horizontal twin-shaft kneading devolatilizer is turned on, and the speed is set to 35r / min to cut the devolatilized chlorohydrin rubber into small spherical transparent rubber particles and convey them out of the devolatilization system; S4. The devolatilized rubber granules are extruded, metered, and packaged to obtain the finished chlorohydrin rubber. The toluene residue of the copolychlorohydrin rubber was found to be 0.1% by headspace gas chromatography, and the Mooney viscosity ML(1+4) at 100℃ was 61, which meets the product quality requirements.

[0058] Comparative Example 1 Comparative Example 1 provides a method for the continuous preparation of chlorohydrin rubber, which uses a combination of traditional batch polymerization and azeotropic distillation devolatilization to prepare homopolymer chlorohydrin rubber, including the following steps: S1. Toluene (1620 kg), epichlorohydrin (180 kg), and catalyst (triisobutylaluminum, phosphoric acid, and aniline in a mass ratio of 60:120:9) (900 g) are added to a batch reactor, and stirring is started. The reaction temperature is controlled to not exceed 120°C using steam from the reactor jacket. After 3 hours of polymerization, a terminator is added to the reactor and stirred for half an hour. The terminator is a 10 wt% toluene solution of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the amount of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is 1% of the monomer mass. S2. The reaction solution after the polymerization is terminated is pumped into an azeotropic reactor containing 2000 kg of hot water and steam-heated for 8 hours to evaporate the remaining toluene and the hot water to obtain rubber particles. The particles are then passed through a vibrating screen to remove surface water. The particles are then dried in a drying oven for 12 hours to obtain raw rubber. Finally, the raw rubber is extruded, metered, and packaged to obtain the finished homopolymer polyvinyl chloride rubber.

[0059] Comparative Example 2 Comparative Example 2 provides a method for the continuous preparation of chlorohydrin rubber, which uses a combination of traditional batch polymerization and azeotropic distillation devolatilization to prepare copolychlorohydrin rubber, including the following steps: S1. Toluene (1440 kg), epichlorohydrin and ethylene oxide (epicochlorohydrin to ethylene oxide mass ratio 2:1) (360 kg), and catalyst (triisobutylaluminum, phosphoric acid, and aniline mass ratio 50:140:12) (1200 g) are added to a batch reactor, and stirring is started. The reaction temperature is controlled to not exceed 120°C using steam from the reactor jacket. After 3 hours of polymerization, a terminator is added to the reactor and stirred for half an hour. The terminator is a 10 wt% toluene solution of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the amount of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is 1% of the monomer mass. S2. The reaction solution after the polymerization is terminated is pumped into an azeotropic reactor containing 2000 kg of hot water and steam-heated for 8 hours to evaporate the remaining toluene and the hot water to obtain rubber particles. The particles are then passed through a vibrating screen to remove surface water. The particles are then dried in a drying oven for 12 hours to obtain raw rubber. Finally, the raw rubber is extruded, metered, and packaged to obtain the finished copolyvinyl chloride rubber product.

[0060] Table 1 Comparison of the effects of the embodiments and comparative examples. As shown in Table 1, compared with Comparative Examples 1 and 2, Examples 1 and 2 exhibit lower toluene and moisture residues, maintain a Mooney viscosity within the acceptable range of 45-75, higher tensile strength and elongation, and a lower molecular weight distribution index (PDI). The continuous process of this invention eliminates the need for adding large amounts of water as an azeotropic agent, saving energy consumption by approximately 40% for removing this water. Furthermore, it eliminates the need for vibration dehydration and oven drying, significantly shortening operation time, simplifying the process, and substantially improving production efficiency.

[0061] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for the continuous preparation of chlorohydrin rubber, characterized in that, Includes the following steps: S1. Toluene, monomer and catalyst are continuously fed into a pipeline reactor, and the reaction temperature is controlled to carry out a continuous polymerization reaction. After the reaction is completed, a terminator is added to obtain a chlorohydrin rubber reaction solution. S2. The chlorohydrin rubber reaction solution is fed into the first horizontal twin-shaft kneading devolatilizer for the first vacuum devolatilization, so that the solid content of the material reaches 65~85% and quasi-solid chlorohydrin rubber is obtained. S3. The quasi-solid chlorohydrin rubber is fed into the second horizontal twin-shaft kneading devolatilizer for a second vacuum devolatilization. Moisture is added during the devolatilization process, and the material temperature is controlled to not exceed 100°C in the later stage of devolatilization. After the devolatilization is completed, the material is discharged and cut to obtain the devolatilized rubber granules. S4. The devolatilized rubber particles are extruded, measured, and packaged to obtain the finished chlorohydrin rubber product.

2. The method for continuous preparation of chlorohydrin rubber according to claim 1, characterized in that, In step S1, the pipeline reactor includes three temperature control zones and one cooling zone, wherein the temperatures of the three temperature control zones are as follows: the polymerization temperature of the front section is 40~60℃, the polymerization temperature of the middle section is 60~80℃, and the polymerization temperature of the rear section is 80~120℃.

3. The method for continuous preparation of chlorohydrin rubber according to claim 1, characterized in that, In step S1, the feed mass ratio of toluene, monomer and catalyst is (1~9):1:(0.001~0.05).

4. The method for continuous preparation of chlorohydrin rubber according to claim 3, characterized in that, The monomer is one or more of epichlorohydrin, ethylene oxide, and propylene oxide.

5. The method for continuous preparation of chlorohydrin rubber according to claim 1, characterized in that, In step S1, the residence time of the material in the pipeline reactor is 0.5 to 2 hours.

6. The method for continuous preparation of chlorohydrin rubber according to claim 1, characterized in that, In step S2, the vacuum degree inside the first horizontal biaxial kneading devolatilizer is -85~-95kPa, and the devolatilization temperature is 60~100℃.

7. The method for continuous preparation of chlorohydrin rubber according to claim 6, characterized in that, The main motor of the first horizontal twin-shaft kneading and de-wiring machine has a stirring speed of 3~15 r / min, and the auxiliary motor has a stirring speed of 10~100 r / min.

8. The method for continuous preparation of chlorohydrin rubber according to claim 1, characterized in that, In step S3, the vacuum degree inside the second horizontal biaxial kneading devolatilizer is -95~-99kPa, and the devolatilization temperature is 90~120℃.

9. The method for continuous preparation of chlorohydrin rubber according to claim 8, characterized in that, The main motor of the second horizontal twin-shaft kneading and de-wiring machine has a stirring speed of 20~40 r / min, and the auxiliary motor has a stirring speed of 10~100 r / min.

10. The method for continuous preparation of chlorohydrin rubber according to claim 1, characterized in that, In step S3, the second horizontal biaxial kneading and de-waxing machine is divided into three chambers, and the water replenishment flow rate of each chamber is independently 0.5~1.5kg / h.

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