An interfacial polycondensation tubular reactor for the preparation of polycarbonates

Abstract

The utility model relates to a kind of interfacial polycondensation tubular reactor for preparing polycarbonate, using U-shaped structure, straight pipe section built-in spiral disturbance device, high viscosity melt is disturbed by active or passive mode, eliminate laminar flow and strengthen mixing;External configuration multistage independent temperature control module, accurately control each reaction section temperature.Reactor inlet and outlet and temperature control interface adopt high-temperature-resistant, corrosion-resistant sealing design, U-shaped modular flange connection is convenient to disassemble and clean and continuous extension.This design solves the problems of uneven heat transfer, material residue and poor flow distribution of traditional horizontal disc reactor and tubular reactor, and has the following advantages: improve the uniformity of melt flow, avoid local overheating and excessive polycondensation;Segmented temperature control optimizes reaction efficiency and molecular weight distribution;Compact structure without dead angle, reduce the risk of side reaction and inner wall corrosion, suitable for polycarbonate efficient continuous synthesis.

Description

Technical Field

[0001] This invention belongs to the technical field of tubular reactors, specifically relating to an interfacial polycondensation tubular reactor for preparing polycarbonate. Background Technology

[0002] Polycarbonate is widely used in many industrial fields due to its excellent mechanical properties, optical transparency, and heat and weather resistance. Industrially, polycarbonate is mainly synthesized using the phosgene process, which uses bisphenol A and phosgene as raw materials and carries out an interfacial polycondensation reaction in the presence of an alkaline catalyst.

[0003] In the traditional phosgene process for synthesizing polycarbonate, horizontal disc reactors are commonly used for interfacial polycondensation. In these reactors, the prepolymerized melt undergoes further polycondensation under high temperature and high vacuum conditions, while the small-molecule byproduct phenol needs to be removed. Disc reactors can utilize the rotating discs to form a melt film, increasing the surface area for volatiles and thus better promoting phenol volatilization and the interfacial polycondensation reaction.

[0004] However, disc reactors generally have some drawbacks: high-viscosity prepolymer melt is prone to remain in the gap between the disc and the cylinder, resulting in reduced heat transfer efficiency; some materials stay for too long at high temperatures, leading to uneven heat transfer, which may cause excessive polycondensation and broaden the molecular weight distribution of the product, affecting the mechanical properties of polycarbonate products; in addition, uneven distribution of material residence time inside the reactor can also exacerbate the generation of side reactions, affecting the optical properties of polycarbonate products.

[0005] Tubular reactors enable continuous reaction processes through the continuous flow of materials within the tubes, and can handle reaction conditions such as high temperature and high pressure. However, existing tubular reactors have certain limitations when processing high-viscosity materials. Uneven flow of materials within the reaction tubes can easily lead to localized overheating or incomplete reactions, affecting product quality and reaction efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide an interfacial polycondensation tubular reactor for preparing polycarbonate, in order to solve the problems mentioned in the background art, such as uneven melt flow and heat transfer inside the horizontal disc reactor, easy occurrence of side reactions, complex structure leading to material accumulation and corrosion of the inner wall, and difficulty in cleaning; in addition, it also solves the problems of uneven melt flow and low temperature control accuracy in existing tubular reactors.

[0007] To achieve the above objectives, this utility model proposes the following technical solution: a tubular reactor for preparing polycarbonate through interfacial polycondensation, comprising a U-shaped unit reactor body, the reactor body including a material inlet and a material outlet; a flange structure is provided at the material outlet of the reactor body, allowing connection to a finished product outlet or the next reactor; a flow-turbing device is installed inside the straight tube section of the reactor body, the flow-turbing device including a central shaft and at least one set of flow-turbing blades spirally arranged along the central shaft, the tail end of the central shaft extending to the outside of the reactor body; the flow-turbing device is passive, the tail end of the central shaft of the flow-turbing device is connected to the reactor body through a sealed bearing; the head end of the flow-turbing device is connected to a fixed bracket through a bearing, the fixed bracket being fixed to the inner wall of the reactor body; a multi-stage temperature control device covering the entire reaction process is provided outside the reactor body, with gaps between each stage of the temperature control device; a heat transfer medium inlet and outlet are provided outside the multi-stage temperature control device; the multi-stage temperature control device can be independently adjusted according to different reaction stages; the material inlet of the reactor, the heat transfer medium inlet and outlet of the temperature control device, and the material outlet are all equipped with sealing gaskets; the sealing gaskets are made of high-temperature resistant and corrosion-resistant materials.

[0008] The turbulence device is configured as an active turbulence device. When active turbulence is used, the tail end of the central shaft of the turbulence device is connected to an external motor through a coupling.

[0009] The reactor body's inner wall and the turbulence device are made of corrosion-resistant and heat-resistant materials suitable for the polycarbonate interfacial polycondensation reaction.

[0010] By adopting the above technical solution, the materials participating in the reaction pass through the reaction zone covered by a multi-stage temperature control device in sequence from the inlet inside the reactor. The first to fifth stage temperature control devices work independently during the reaction, so that the reactor body provides precise temperature control at different stages of the reaction.

[0011] Furthermore, the reactant inlet is positioned at the starting position perpendicular to the turbulence blades of the turbulence device.

[0012] Furthermore, gaps are provided between the multi-stage temperature control devices.

[0013] Furthermore, the rear end of the turbulence device is connected to the reactor body via a sealed bearing, and the front end of the turbulence device is connected to the fixed support via a bearing.

[0014] Furthermore, the fixed support is fixedly connected to the inner wall of the reactor body.

[0015] Furthermore, sealing gaskets are provided at the reactant inlet, the heat transfer medium inlet and outlet of the temperature control device, and the material outlet.

[0016] Furthermore, the material outlet is equipped with a flange that can be connected to the finished product outlet or to the next U-shaped unit reactor.

[0017] In summary, the beneficial technical effects of this utility model compared with the prior art are as follows:

[0018] (1) When the reactor of this utility model is running, in the reaction environment of high temperature and high vacuum, the melt needs to pass through the turbulence device when entering the reactor, which can accelerate the flow of the melt and effectively improve the phenomenon of uneven flow and laminar flow of the melt.

[0019] (2) In this utility model, the temperature control accuracy of different reaction stages is improved by using a multi-stage temperature control device, which can effectively improve the reaction efficiency and avoid the situation where material accumulation leads to excessive condensation and side reactions affect product performance.

[0020] (3) The internal melt flow channel design and turbulence device of the reactor of this utility model can effectively promote melt flow and avoid the phenomenon of corrosion of the inner wall of the reactor due to material accumulation. At the same time, it is easy to disassemble and clean the reactor. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an interfacial polycondensation tubular reactor for preparing polycarbonate, which operates under active turbulence.

[0022] Figure 2 This is a schematic diagram of the structure of an interfacial polycondensation tubular reactor for preparing polycarbonate, which operates in a passive turbulence mode according to this utility model.

[0023] Figure 3 This is a schematic diagram of the turbulence device structure of an interfacial polycondensation tubular reactor for preparing polycarbonate according to the present invention.

[0024] Explanation of the labels in the diagram:

[0025] 1. Drive motor; 2. Material inlet; 3. Heat transfer medium inlet; 4. Heat transfer medium outlet; 5. Turbulence device; 6. Multi-stage temperature control device; 7. Bearing; 8. Fixed bracket; 9. Material outlet; 10. Sealed bearing. Detailed Implementation

[0026] The technical solution of this utility model patent will be described in detail and clearly below with reference to the accompanying drawings. Obviously, the embodiments described are only a part of the embodiments of this utility model patent, and not all of them. Based on the embodiments of this utility model patent, those skilled in the art can directly and unambiguously determine all other embodiments covered by this utility model patent without inventive work. These other embodiments all fall within the protection scope of this utility model patent.

[0027] Example 1:

[0028] like Figure 1 As shown, an interfacial polycondensation tubular reactor for preparing polycarbonate includes a reactor body with a U-shaped structure, comprising a straight tube section and two curved sections to form a continuous material flow channel.

[0029] A flow-turbing device 5 is provided in the straight pipe section of the reactor body, such as... Figure 3 As shown, the device, through its fixed support at the front end and the design of the baffle blades in the middle, is used to agitate the flow of melt through the reactor tube, in order to prevent laminar flow and improve material mixing.

[0030] The tail end of the central shaft of the turbulence device 5 passes through the reactor and is connected to a drive motor 1. The motor is responsible for driving the turbulence device to rotate, so as to disturb the flow of the melt.

[0031] The reactor body is equipped with a multi-stage temperature control device 6 on the outside, which achieves precise control of the internal temperature of the reactor through the external heat transfer medium inlet 3 and the heat transfer medium outlet 4.

[0032] The tail end of the turbulence device is connected to the reactor body via a sealed bearing 10 to ensure the sealing of the reactor interior.

[0033] The front end of the turbulence device is connected to the fixed bracket 8 via a bearing 7. The fixed bracket 8 is fixedly connected to the inner wall of the reactor body to ensure the stability of the turbulence device.

[0034] The reactor body is equipped with a material inlet 2 and a material outlet 9 on its exterior, both fitted with sealing gaskets to ensure the reactor's airtightness. The material outlet 9 is equipped with a flange, allowing connection to the next U-shaped unit reactor for continuous production and easy disassembly and cleaning.

[0035] The working principle of Embodiment 1 of this utility model is as follows: The pre-reacted melt material enters the reactor from the material inlet 2. The turbulence device 5 rotates continuously at a fixed speed under the drive of the drive motor 1. The pre-reacted melt material has a certain viscosity and is driven forward between the turbulence spiral blades of the turbulence device 5, changing the original laminar flow state and preventing some melt material from staying in the reactor for a long time. At the same time, to ensure the temperature uniformity of the melt material throughout the reaction process, the multi-stage temperature control device 6 independently controls the temperature of each section of the reactor body, achieving precise temperature control at each stage of the reaction. The material outlet 9 can be reconnected to the reactor to form a longer reaction process, improving the applicability of the reaction.

[0036] Example 2:

[0037] like Figure 2As shown, an interfacial polycondensation tubular reactor for preparing polycarbonate is the same as in Example 1. The main body of the reactor in this example is also a U-shaped structure, including a straight tube section and two curved sections.

[0038] The reactor body is also equipped with a flow disturbance device 5 in the straight tube section, but the end of its central shaft is not connected to a drive motor. Instead, it is designed as a structure that can be rotated by the reaction flow.

[0039] The reactant inlet 2 is located perpendicular to the starting position of the turbulence blades of the turbulence device, so that the reactant flow drives the turbulence device 5 to rotate when it enters the reactor.

[0040] Similar to Example 1, a multi-stage temperature control device 6 is provided on the outside of the reactor body to achieve precise temperature control. Gaps are provided between the multi-stage temperature control devices 6 to facilitate the flow of the reaction stream and the rotation of the turbulence-inducing device 5.

[0041] The front end of the turbulence device 6 is connected to the fixed bracket 8 via a bearing, and the fixed bracket 8 is fixedly connected to the inner wall of the reactor body to ensure the stability of the turbulence device.

[0042] Similar to Example 1, the reactor body is provided with a material inlet 2 and a material outlet 9 on the outside, both equipped with sealing gaskets to ensure the reactor's airtightness.

[0043] Material outlet 9 is equipped with a flange, which can be connected to the next U-shaped unit reactor to achieve continuous production.

[0044] The working principle of Embodiment 2 of this utility model is as follows: the pre-reacted melt material enters the reactor from the reactor material inlet 2. Driven by the reaction flow, the flow-stirring device 5 rotates continuously at a dynamic rate, changing the original laminar flow state and preventing some melt material from remaining in the reactor for an extended period. Similar to the working principle of Embodiment 1, to ensure the temperature uniformity of the melt material throughout the reaction process, a multi-stage temperature control device 6 independently controls the temperature of each section of the reactor body, achieving precise temperature control at each stage of the reaction. During this process, the fixed connection between the fixed support 8 and the inner wall of the reactor body, as well as the high-precision fit of the bearing 7, provide stable support for the flow-stirring device 5, ensuring that the flow-stirring device 5 can effectively agitate the melt flow under the influence of the material flow. Embodiment 2 not only improves reaction efficiency but also enhances the adaptability and operational flexibility of the reactor.

[0045] The pre-reacted melt material can achieve good flow state and precise segmented reaction temperature control throughout the reaction process, avoiding incomplete reaction due to uneven reaction temperature of reactants; there are no dead flow corners inside the reactor, effectively preventing excessive condensation and corrosion of the reactor wall caused by the accumulation of reacting melt material inside the reactor; the reactor structure is simple to design, easy to disassemble and clean, and multiple reactors can be connected, making it highly applicable.

Claims

1. A tubular reactor for the interfacial polycondensation of polycarbonate, characterized in that: The reactor comprises a U-shaped unit reactor body, which includes a material inlet and a material outlet. The material outlet of the reactor body is equipped with a flange structure, allowing connection to a finished product outlet or the next reactor. A flow-turbing device is installed inside the straight pipe section of the reactor body. This device includes a central shaft and at least one set of flow-turbing blades spirally arranged along the central shaft, with the tail end of the central shaft extending to the outside of the reactor body. The flow-turbing device is passive, with the tail end of the central shaft connected to the reactor body via a sealed bearing. The head end of the flow-turbing device is connected to a fixed support via a bearing, and the fixed support is fixed to the inner wall of the reactor body. A multi-stage temperature control device covering the entire reaction process is installed outside the reactor body, with gaps between each stage. A heat transfer medium inlet and outlet are located outside the multi-stage temperature control device. The multi-stage temperature control device can be independently adjusted according to different reaction stages. Sealing gaskets are provided at the reactor's material inlet, the heat transfer medium inlet and outlet of the temperature control device, and the material outlet. These sealing gaskets are made of high-temperature resistant and corrosion-resistant materials.

2. The interfacial polycondensation tubular reactor for preparing polycarbonate according to claim 1, characterized in that: The turbulence device is configured as an active turbulence device. When active turbulence is used, the tail end of the central shaft of the turbulence device is connected to an external motor through a coupling.

3. The interfacial polycondensation tubular reactor for preparing polycarbonate according to claim 1, characterized in that: The material inlet is located in the straight pipe section of the U-shaped reactor body, perpendicular to the starting end of the turbulence blades of the turbulence device.

4. The interfacial polycondensation tubular reactor for preparing polycarbonate according to claim 1, characterized in that: The reactor body's inner wall and the turbulence device are made of corrosion-resistant and heat-resistant materials suitable for the polycarbonate interfacial polycondensation reaction.

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