Continuous preparation method and device for polycarbonate

Abstract

The invention provides a continuous preparation method and device for polycarbonate, and belongs to the technical field of organic polymer synthesis. The continuous polycarbonate preparation device comprises a raw material pretreatment unit, a film evaporator arranged in the vertical direction, a vacuum separation unit, an extrusion molding unit and a control system, and the interior of the film evaporator is divided into a low-temperature prepolymerization section, a medium-temperature reaction section and a high-temperature polycondensation section; a scraper connected to a middle shaft is arranged in the film evaporator, the scraper of the low-temperature pre-polymerization section is a two-blade or three-blade symmetrical scraper perpendicular to the wall of the reactor, the scraper of the medium-temperature reaction section is a downward push type spiral scraper with a push angle of 1-5 degrees, and the scraper of the high-temperature polycondensation section is a downward push type spiral scraper with a push angle of 5-10 degrees. A sectional type film evaporator is adopted as a reactor, and continuous production of polycarbonate is realized through combination of precise sectional temperature control, special scraper design, continuous feeding and by-product vacuum separation.

Description

Technical Field

[0001] This invention relates to the field of organic polymer synthesis technology, and in particular to a continuous preparation method and apparatus for polycarbonate. Background Technology

[0002] Polycarbonate (PC) is a versatile thermoplastic engineering plastic renowned for its excellent overall properties, finding applications in numerous fields including electronics, home appliances, building materials, automotive manufacturing, medical equipment, aerospace, optics, and security equipment. Interfacial polycondensation using phosgene as a raw material was the earliest industrialized production method and is technologically mature. However, due to its environmental pollution, its application is now strictly limited. In contrast, non-phosgene melt transesterification avoids the use of highly toxic phosgene and harmful organic solvents such as dichloromethane, making it more environmentally friendly and thus the preferred technology for new production facilities.

[0003] Existing melt transesterification methods for producing polycarbonate mostly employ batch reactions or multi-reactor series continuous reactions, constituting a multi-stage process. First, dihydroxy compounds and diphenyl carbonate (DPC) are melted, then an alkaline catalyst is added, and the reaction proceeds under atmospheric pressure. Subsequently, the temperature is raised to 200–230°C, and the system is maintained under reduced pressure (2–4 kPa) to promote pre-polymerization. In the final stage, the temperature is further raised to 270–300°C, while the pressure is reduced to below 100 Pa, allowing the reaction to continue until polycarbonate is formed. In the later stages of the polycondensation reaction, prolonged exposure to high temperatures can lead to degradation, disproportionation, and cross-linking of the molten polycarbonate segments, adversely affecting product quality. Furthermore, dihydroxy compounds are prone to thermal decomposition at temperatures above 150°C; therefore, reactor selection and residence time control are crucial for the production of high-performance polycarbonate. Traditional processes have the following shortcomings: First, the temperature control precision during the reaction is low, making it impossible to accurately adjust the temperature according to the needs of different reaction stages, resulting in uneven reaction rates, a large amount of by-products, and affecting product purity and molecular weight distribution. Second, the residence time of materials in the reaction system is uneven, which can easily lead to incomplete or excessive local reactions, reducing product quality stability. Third, the separation efficiency of phenol and small molecule by-products generated in the reaction is low, and their residues in the product can affect the mechanical and processing properties of polycarbonate. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a continuous preparation method and apparatus for polycarbonate. The apparatus of this invention enables efficient and continuous preparation of polycarbonate, improving product quality and stability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a continuous polycarbonate production apparatus, comprising a raw material pretreatment unit, a vertically arranged thin-film evaporator, a vacuum separation unit, an extrusion molding unit, and a control system. The outlet of the raw material pretreatment unit is connected to the inlet of the thin film evaporator, and the outlet of the thin film evaporator is connected to the inlet of the extrusion molding unit. The extrusion molding unit also includes a chain terminator inlet. The thin-film evaporator is connected to the vacuum separation unit; The interior of the thin-film evaporator is divided into a low-temperature prepolymerization section, a medium-temperature reaction section, and a high-temperature polycondensation section from top to bottom along the material flow direction. A central shaft is set inside the thin-film evaporator, and scrapers are connected to the central shaft. The scrapers in the low-temperature prepolymerization section are two- or three-bladed symmetrical scrapers perpendicular to the reactor wall. The scrapers in the medium-temperature reaction section are downward-propelling spiral scrapers with a propulsion angle of 1 to 5°. The scrapers in the high-temperature polycondensation section are downward-propelling spiral scrapers with a propulsion angle of 5 to 10°.

[0006] Preferably, the temperature of the low-temperature prepolymerization section is 80~150℃, the temperature of the medium-temperature reaction section is 150~220℃, and the temperature of the high-temperature polycondensation section is 220~300℃.

[0007] Preferably, the height-to-diameter ratio of the thin-film evaporator is 3 to 8:1.

[0008] Preferably, the rotational speed of the central shaft is 30~300 r / min.

[0009] This invention also provides a continuous polycarbonate preparation method, utilizing the continuous polycarbonate preparation apparatus described above, comprising the following steps: The dihydroxy compound, diphenyl carbonate, and alkaline catalyst are mixed in the raw material pretreatment unit to obtain a mixture; The mixture is continuously fed into the top of the thin film evaporator and passes through the low-temperature prepolymerization section, the medium-temperature reaction section and the high-temperature polycondensation section from top to bottom to carry out the polymerization reaction. The polymerization reaction includes prepolymerization, medium-temperature reaction and high-temperature polycondensation carried out in sequence to obtain the polymerization product and other products. The other products are extracted and separated in real time by the vacuum separation unit. The polymer product and chain terminator are end-capped in the extrusion molding unit to obtain polycarbonate.

[0010] Preferably, based on the feed rate of the dihydroxy compound and the contact area between the material and the interior of the thin-film evaporator, the processing capacity of the low-temperature prepolymerization section is 2~4 mol / m³. 2 The processing capacity of the mesophilic reaction section is 2~4 mol / m³ / h. 2 The high-temperature polycondensation section has a processing capacity of 1~3 mol / m³ / h. 2 / h.

[0011] Preferably, the molar ratio of the diphenyl carbonate to the dihydroxy compound is 1 to 1.05:1.

[0012] Preferably, the molar ratio of the alkaline catalyst to the dihydroxy compound is 10. -7 ~10 -5 :1.

[0013] Preferably, the molar ratio of the chain terminator to the dihydroxy compound is 10. -5 ~10 -3 :1.

[0014] Preferably, the dihydroxy compound includes one or more of bisphenol A, isosorbide, 1,4-butanediol and 1,4-cyclohexanediethanol.

[0015] This invention provides a continuous polycarbonate preparation apparatus, comprising a raw material pretreatment unit, a vertically arranged thin-film evaporator, a vacuum separation unit, an extrusion molding unit, and a control system. The outlet of the raw material pretreatment unit is connected to the inlet of the thin-film evaporator, and the outlet of the thin-film evaporator is connected to the inlet of the extrusion molding unit. The extrusion molding unit also includes a chain terminator inlet. The thin-film evaporator is connected to the vacuum separation unit. The interior of the thin-film evaporator is divided into a low-temperature prepolymerization section, a medium-temperature reaction section, and a high-temperature polycondensation section from top to bottom along the material flow direction. A central shaft is provided inside the thin-film evaporator, and scrapers are connected to the central shaft. The scrapers in the low-temperature prepolymerization section are two- or three-bladed symmetrical scrapers perpendicular to the reactor wall. The scrapers in the medium-temperature reaction section are downward-propelling spiral scrapers with a propulsion angle of 1-5°. The scrapers in the high-temperature polycondensation section are downward-propelling spiral scrapers with a propulsion angle of 5-10°.

[0016] Compared with existing technologies, this invention uses a vertical thin-film evaporator with segmented temperature control as the reactor. By combining precise segmented temperature control, a dedicated scraper design, continuous feeding, and vacuum separation of by-products, continuous production of polycarbonate is achieved. The beneficial effects of this invention are as follows: Precise temperature control and high reaction efficiency: The thin-film evaporator with segmented temperature control precisely matches the reaction requirements of prepolymerization, medium-temperature reaction and high-temperature polycondensation in three temperature ranges, avoiding problems such as increased side reactions and incomplete reaction caused by excessively high or low temperatures, and significantly improving the reaction rate and reaction conversion rate.

[0017] Uniform material flow and controllable residence time: Through the scraper design adapted to different temperature ranges, the low temperature range ensures uniform film formation of materials, the medium temperature range ensures sufficient reaction, and the high temperature range avoids material decomposition, achieving precise control of material residence time, ensuring uniform molecular weight distribution of products, and improving product quality stability.

[0018] Highly efficient byproduct separation: The vacuum system extracts other products generated in the reaction (including phenol and small molecule byproducts) in real time, maintaining a high vacuum environment in the reactor. This not only promotes the forward reaction but also reduces byproduct residues and improves product purity and mechanical properties.

[0019] High degree of continuity and high production efficiency: The entire production process, from raw material pretreatment, feeding, reaction, by-product separation to extrusion molding, achieves fully continuous operation. Compared with batch production or multi-reactor series production, it greatly improves production efficiency, reduces labor costs, and is suitable for large-scale industrial production.

[0020] The equipment has a simple structure and a small footprint: it uses a vertical thin-film evaporator as the core reactor, integrating raw material pretreatment, vacuum separation, extrusion molding and other units. The equipment has a high degree of integration, a compact structure, and a footprint that is much smaller than that of traditional multi-reactor series systems, thus reducing equipment investment costs.

[0021] This invention also provides a continuous preparation method for polycarbonate, which enables efficient, continuous and stable production of polycarbonate, improves product quality and production efficiency, reduces production costs, and produces polycarbonate products with high number-average molecular weight, narrow molecular weight distribution index and high impact strength. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the continuous polycarbonate preparation apparatus of the present invention. Detailed Implementation

[0023] This invention provides a continuous polycarbonate preparation apparatus, including a raw material pretreatment unit, a vertically arranged thin film evaporator, a vacuum separation unit, an extrusion molding unit (vacuum system), and a control system (remote control system). The outlet of the raw material pretreatment unit is connected to the inlet of the thin film evaporator, and the outlet of the thin film evaporator is connected to the inlet of the extrusion molding unit. The extrusion molding unit also includes a chain terminator inlet. The thin-film evaporator is connected to the vacuum separation unit; The interior of the thin-film evaporator (thin-film evaporation reactor) is divided into a low-temperature prepolymerization section (low-temperature reaction zone), a medium-temperature reaction section (medium-temperature reaction zone), and a high-temperature polycondensation section (high-temperature reaction zone) from top to bottom along the material flow direction. A central shaft is set inside the thin-film evaporator, and scrapers are connected to the central shaft. The scrapers in the low-temperature prepolymerization section are two- or three-bladed symmetrical scrapers perpendicular to the reactor wall. The scrapers in the medium-temperature reaction section are downward-propelling spiral scrapers with a propulsion angle of 1 to 5°. The scrapers in the high-temperature polycondensation section are downward-propelling spiral scrapers with a propulsion angle of 5 to 10°.

[0024] Figure 1This is a schematic diagram of the continuous polycarbonate preparation apparatus of the present invention. The following is in conjunction with... Figure 1 The continuous polycarbonate preparation apparatus of the present invention will be described.

[0025] The continuous polycarbonate preparation apparatus of the present invention includes a raw material pretreatment unit. The function of the raw material pretreatment unit is to heat and pre-melt and mix the raw material dihydroxy compound, diphenyl carbonate and alkaline catalyst to ensure that the raw material is in a uniform melt state, which facilitates subsequent mixing and feeding. The heating and pre-melting temperature is set according to the melting point of the raw material to ensure that the raw material is completely melted and does not decompose.

[0026] In this invention, the raw material pretreatment unit is preferably a raw material melting vessel, and the raw material melting vessel preferably uses a pump to feed molten raw materials into the thin-film evaporator.

[0027] The continuous polycarbonate preparation apparatus of the present invention includes a thin-film evaporator, which is preferably equipped with a segmented independent heating device to achieve precise temperature control in each temperature range; the thin-film evaporator is equipped with a special scraper, the form of which is adjusted according to different temperature ranges to adapt to the material state in different reaction stages.

[0028] The continuous polycarbonate preparation apparatus of the present invention includes a vacuum separation unit, which is used for vacuum control of the reaction system and separation of phenol and small molecule by-products generated during the reaction, maintaining the set vacuum level in the thin film evaporator, and promoting the forward reaction. The vacuum level is preferably 10~1000 Pa, and can specifically be 10, 50, 100, 200, 300, 400, 600, 700, 800 or 1000 Pa.

[0029] In this invention, the vacuum separation unit preferably employs a combination of a Roots vacuum pump and a mechanical vacuum pump.

[0030] The polycarbonate continuous production apparatus of the present invention includes an extrusion molding unit, which preferably includes a pump and an extruder. The pump preferably includes a gear metering pump, which is used to accurately inject the polymerized product after high-temperature polycondensation into the extruder. The chain terminator is preferably introduced into the extruder through a side feed port. The extruder is used to further react and end-cap the material to form polycarbonate, and then extrude it (such as pelletizing, tableting, etc.).

[0031] In this invention, the extruder is preferably a twin-screw extruder.

[0032] The polycarbonate continuous production apparatus of the present invention includes a control system for controlling the operating parameters of each unit, including the raw material pretreatment temperature, the temperature of each section of the thin film evaporator, the feed rate, the vacuum degree, the gear metering pump speed, the extruder speed, and the amount of chain terminator added, to ensure that the entire production process is stable and controllable.

[0033] In this invention, the control system is preferably a PLC control system. The scraper design of this invention is adapted to different temperature ranges. Specifically, in the low-temperature prepolymerization section, a two- or three-bladed symmetrical scraper (two blades are distributed at a 180° angle around the axis, and three blades are distributed at a 120° angle around the axis) is used to uniformly scrape the molten raw materials onto the reactor wall to form a thin liquid film, promoting mixing and prepolymerization reaction. In the medium-temperature reaction section, a spiral scraper with a downward-propelling function is used with a small propulsion angle (1~5°, specifically 1°, 2°, 3°, 4° or 5°), which ensures uniform material distribution and slows down the material flow to ensure a complete reaction. In the high-temperature polycondensation section, a spiral scraper with a downward-propelling function is used with a larger propulsion angle (5~10°, specifically 5°, 6°, 7°, 8°, 9° or 10°), which accelerates the material flow rate, prevents the material from decomposing due to prolonged residence time at high temperatures, and ensures complete polycondensation reaction.

[0034] In this invention, the temperature of the low-temperature prepolymerization section is preferably 80~150℃, specifically 80, 90, 100, 110, 120, 130, 140 or 150℃; the temperature of the medium-temperature reaction section is preferably 150~220℃, specifically 150, 160, 170, 180, 190, 200, 210 or 220℃; and the temperature of the high-temperature polycondensation section is preferably 220~300℃, specifically 220, 230, 240, 250, 260, 270, 280, 290 or 300℃.

[0035] In this invention, the height-to-diameter ratio of the thin-film evaporator is preferably 3 to 8:1, specifically 3:1, 4:1, 5:1, 6:1, 7:1 or 8:1.

[0036] In this invention, the rotational speed of the central shaft (i.e., the rotational speed of the scraper connected to the central shaft of the thin film evaporator) is preferably 30~300 r / min, specifically 30, 50, 60, 100, 120, 150, 180, 200, 250 or 300 r / min.

[0037] This invention also provides a continuous polycarbonate preparation method, utilizing the continuous polycarbonate preparation apparatus described above, comprising the following steps: The dihydroxy compound, diphenyl carbonate, and alkaline catalyst are mixed in the raw material pretreatment unit to obtain a mixture; The mixture is continuously fed into the top of the thin film evaporator and passes through the low-temperature prepolymerization section, the medium-temperature reaction section and the high-temperature polycondensation section from top to bottom to carry out the polymerization reaction. The polymerization reaction includes prepolymerization, medium-temperature reaction and high-temperature polycondensation carried out in sequence to obtain polymerization products and by-products. The by-products are extracted and separated in real time by the vacuum separation unit. The polymer product and chain terminator are end-capped in the extrusion molding unit to obtain polycarbonate.

[0038] Unless otherwise specified, all raw materials used in this invention are commercially available products in the field.

[0039] In this invention, a dihydroxy compound, diphenyl carbonate, and an alkaline catalyst are mixed in the raw material pretreatment unit to obtain a mixture.

[0040] In this invention, the molar ratio of diphenyl carbonate to dihydroxy compound is preferably 1 to 1.05:1, specifically 1:1, 1.01:1, 1.03:1 or 1.05:1.

[0041] In this invention, the molar ratio of the alkaline catalyst to the dihydroxy compound is preferably 10. -7 ~10 -5 :1, specifically 10 -7 1, 10 -6 : 1 or 10 -5 :1.

[0042] In this invention, the dihydroxy compound preferably includes one or more of bisphenol A, isosorbide, 1,4-butanediol and 1,4-cyclohexanediethanol.

[0043] In this invention, the alkaline catalyst preferably comprises sodium methoxide.

[0044] In this invention, the dihydroxy compound, diphenyl carbonate, and alkaline catalyst are fed into the raw material pretreatment unit in proportion for heating and pre-melting mixing to ensure that the raw materials are completely melted and homogeneous without solid particles.

[0045] After obtaining the mixture, the present invention continuously feeds the mixture into the top of the thin film evaporator, and passes it from top to bottom through the low-temperature prepolymerization section, the medium-temperature reaction section and the high-temperature polycondensation section to carry out the polymerization reaction. The polymerization reaction includes prepolymerization, medium-temperature reaction and high-temperature polycondensation carried out in sequence to obtain polymerization products and by-products. The by-products are extracted and separated in real time by the vacuum separation unit.

[0046] In this invention, based on the feed rate of the dihydroxy compound and the contact area between the material and the interior of the thin-film evaporator, the processing capacity of the low-temperature prepolymerization section is preferably 2~4 mol / m³.2 / h, specifically 2, 2.5, 2.7, 3, 3.2, 3.5 or 4 mol / m 2 The preferred processing capacity of the mesophilic reaction section is 2-4 mol / m³ / h. 2 / h, specifically 2, 2.5, 2.7, 3, 3.2, 3.5 or 4 mol / m 2 The processing capacity of the high-temperature polycondensation section is preferably 1~3 mol / m³ / h. 2 / h, specifically 1, 1.5, 1.7, 2, 2.5 or 3 mol / m 2 / h.

[0047] In a specific embodiment of the present invention, the heating areas (i.e., the contact area between the inside of the thin-film evaporator and the material) of the low-temperature prepolymerization section, the medium-temperature reaction section, and the high-temperature polycondensation section are all 10m². 2 10m 2 and 15m 2 .

[0048] In this invention, the polymerization reaction is a staged reaction: the mixture passes through three temperature zones sequentially from top to bottom in a thin-film evaporator, completing three stages: prepolymerization, intermediate-temperature reaction, and high-temperature polycondensation, wherein: Low-temperature prepolymerization section: Under the action of two or three symmetrical scrapers, the material is uniformly scraped onto the reactor wall to form a thin liquid film. The dihydroxy compound and diphenyl carbonate undergo a preliminary prepolymerization reaction to generate a low molecular weight polycarbonate prepolymer. The reaction temperature is 80~150℃, preferably 100~130℃. Medium-temperature reaction section: Under the action of a spiral scraper with a propulsion angle of 1~5°, the material is slowly pushed downwards and continues to polymerize, with the molecular weight gradually increasing. The small amount of phenol and small molecule by-products generated during the reaction are extracted and separated in real time by the vacuum system. The reaction temperature is 150~220℃, preferably 180~200℃. High-temperature polycondensation section: Under the action of a spiral scraper with a propulsion angle of 5~10°, the material is rapidly pushed downwards, undergoing high-temperature polycondensation, and the molecular weight is further increased. The phenol and small molecule by-products generated in the reaction are continuously extracted and separated by the vacuum system to maintain a vacuum degree of 10~1000 Pa in the reactor, preferably 10~200 Pa, and a reaction temperature of 220~300℃, preferably 250~280℃.

[0049] After obtaining the polymer product, the present invention performs end-capping of the polymer product and chain terminator in the extrusion molding unit to obtain polycarbonate.

[0050] In this invention, the molar ratio of the chain terminator to the dihydroxy compound is preferably 10. -5 ~10 -3 :1, specifically 10-5 1, 10 -4 : 1 or 10 -3 :1.

[0051] In this invention, the chain terminator preferably includes p-methoxyphenol.

[0052] The polymer product is preferably precisely injected into the extruder via a gear metering pump, while the chain terminator is added into the extruder simultaneously. The chain terminator is fully mixed with the material to react and seal the ends, terminating the polymerization reaction. The product is then extruded through the extruder and subjected to subsequent molding processes to obtain the polycarbonate.

[0053] In this invention, the speed of the extruder is preferably 100~300 r / min, specifically 100, 200 or 300 r / min, and the temperature is preferably 220~300℃, specifically 220, 250, 280 or 300℃.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Example 1 A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: (1) such as Figure 1 The polycarbonate continuous production apparatus shown consists of: an electrically heated melting kettle for raw material pretreatment; a vertical thin-film evaporator equipped with three independent heating sections: a low-temperature prepolymerization section, a medium-temperature reaction section, and a high-temperature polycondensation section, each with a heating area of ​​10 m². 2 10m 2 and 15m 2 The vacuum separation unit uses a combination of Roots vacuum pump and mechanical vacuum pump, the extrusion molding unit includes a gear metering pump and a twin-screw extruder, the control system uses a PLC control system, and the height-to-diameter ratio of the thin film evaporator is 6:1.

[0056] (2) Production steps: 1. Raw material premixing: Bisphenol A, diphenyl carbonate, and sodium methoxide are mixed in a ratio of 1:1.01:10. -6 The molar ratio of the ingredients is fed into the melting vessel and heated to 110°C to ensure complete melting and uniform mixing.

[0057] 2. Continuous feeding: The molten raw material is continuously fed into the top of the thin-film evaporator via a metering feed pump. Based on the area of ​​the thin-film evaporator reactor, the processing capacity of bisphenol A in the low-temperature prepolymerization section is 2 mol / m².2 / h, the central shaft speed of the thin film evaporator is 60r / min.

[0058] 3. Segmented reaction: The temperature control of each segment of the thin film evaporator is as follows: low temperature prepolymerization segment 110℃, using a three-bladed symmetrical scraper; medium temperature reaction segment 180℃, using a spiral scraper with a propulsion angle of 3°; high temperature polycondensation segment 280℃, using a spiral scraper with a propulsion angle of 8°; the vacuum separation unit maintains the vacuum degree in the evaporator at 50Pa and extracts the phenol and small molecule byproducts generated in the reaction in real time.

[0059] 4. Extrusion Molding: The polymerization product is injected into a twin-screw extruder via a gear metering pump, while p-methoxyphenol chain terminator is added simultaneously. The molar ratio of the chain terminator to bisphenol A is 10:1. -4 1. The extruder speed is 200 r / min, the extrusion temperature is controlled at 280℃, and the product is obtained by pelletizing by a pelletizer.

[0060] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 25,000, the molecular weight distribution index is 1.8, and the impact strength is 89 kJ / m. 2 .

[0061] Example 2 A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: (1) Same as (1) in Example 1.

[0062] (2) Production steps: 1. Raw material premixing: Bisphenol A, diphenyl carbonate, and sodium methoxide are mixed in a ratio of 1:1.03:10. -5 The molar ratio of the ingredients is fed into the melting vessel and heated to 110°C to ensure complete melting and uniform mixing.

[0063] 2. Continuous feeding: The molten raw material is continuously fed into the top of the thin-film evaporator via a metering feed pump. Based on the area of ​​the thin-film evaporator reactor, the processing capacity of bisphenol A in the low-temperature prepolymerization section is 2.25 mol / m². 2 / h, the central shaft speed of the thin film evaporator is 120r / min.

[0064] 3. Segmented reaction: The temperature control of each segment of the thin film evaporator is as follows: low temperature prepolymerization segment 130℃, using two-blade symmetrical scrapers; medium temperature reaction segment 200℃, using spiral scrapers with a propulsion angle of 1°; high temperature polycondensation segment 260℃, using spiral scrapers with a propulsion angle of 5°; the vacuum separation unit maintains the vacuum degree in the evaporator at 100Pa and extracts the phenol and small molecule byproducts generated in the reaction in real time.

[0065] 4. Extrusion Molding: The polymerization product is injected into a twin-screw extruder via a gear metering pump, while p-methoxyphenol chain terminator is added simultaneously. The molar ratio of the chain terminator to bisphenol A is 10:1. -3 1. The extruder speed is 200 r / min, the extrusion temperature is controlled at 280℃, and the product is obtained by pelletizing by a pelletizer.

[0066] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 22,000, the molecular weight distribution index is 1.9, and the impact strength is 85 kJ / m. 2 .

[0067] Example 3 A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: (1) Same as (1) in Example 1.

[0068] (2) Production steps: 1. Raw material premixing: Bisphenol A, diphenyl carbonate, and sodium methoxide are mixed in a ratio of 1:1.03:10. -7 The molar ratio of the ingredients is fed into the melting vessel and heated to 110°C to ensure complete melting and uniform mixing.

[0069] 2. Continuous feeding: The molten raw material is continuously fed into the top of the thin-film evaporator via a metering feed pump. Based on the area of ​​the thin-film evaporator reactor, the processing capacity of bisphenol A in the low-temperature prepolymerization section is 2.25 mol / m². 2 / h, the central shaft speed of the thin film evaporator is 50r / min.

[0070] 3. Segmented reaction: The temperature control of each section of the thin film evaporator is as follows: low temperature prepolymerization section 150℃, using two-blade symmetrical scrapers; medium temperature reaction section 220℃, using spiral scrapers with a propulsion angle of 1°; high temperature polycondensation section 300℃, using spiral scrapers with a propulsion angle of 5°; the vacuum separation unit maintains the vacuum degree in the evaporator at 700Pa and extracts the phenol and small molecule by-products generated in the reaction in real time.

[0071] 4. Extrusion Molding: The polymerization product is injected into a twin-screw extruder via a gear metering pump, while p-methoxyphenol chain terminator is added simultaneously. The molar ratio of the chain terminator to bisphenol A is 10:1. -3 1. The extruder speed is 200 r / min, the extrusion temperature is controlled at 300℃, and the product is granulated by a pelletizer to obtain polycarbonate granules.

[0072] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 24,000, the molecular weight distribution index is 1.8, and the impact strength is 82 kJ / m. 2 .

[0073] Example 4 A continuous preparation apparatus and method for isosorbide-based polycarbonate, as detailed below: (1) Same as (1) in Example 1.

[0074] (2) Production steps: 1. Raw material premixing: Isosorbide, diphenyl carbonate, and sodium methoxide are mixed in a ratio of 1:1.05:10. -6 The molar ratio of the ingredients is fed into the melting vessel and heated to 90°C to ensure complete melting and uniform mixing.

[0075] 2. Continuous Feeding: The molten raw material is continuously fed into the top of the thin-film evaporator via a metering feed pump. Based on the area of ​​the thin-film evaporator reactor, the processing capacity of isosorbide in the low-temperature prepolymerization section is 2.7 mol / m². 2 / h, the central shaft speed of the thin film evaporator is 200r / min.

[0076] 3. Segmented reaction: The temperature control of each segment of the thin film evaporator is as follows: low temperature prepolymerization segment 150℃, using a three-bladed symmetrical scraper; medium temperature reaction segment 220℃, using a spiral scraper with a propulsion angle of 4°; high temperature polycondensation segment 280℃, using a spiral scraper with a propulsion angle of 10°; the vacuum separation unit maintains the vacuum degree in the evaporator at 300Pa and extracts the phenol and small molecule byproducts generated in the reaction in real time.

[0077] 4. Extrusion Molding: The polymerization product is injected into a twin-screw extruder via a gear metering pump, while p-methoxyphenol chain terminator is added simultaneously. The molar ratio of the chain terminator to bisphenol A is 10:1. -3 1. The extruder speed is 200 r / min, the extrusion temperature is controlled at 280℃, and the product is obtained by pelletizing by a pelletizer.

[0078] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 30,000, the molecular weight distribution index is 1.7, and the impact strength is 84 kJ / m. 2 .

[0079] Example 5 A continuous preparation apparatus and method for isosorbide-based polycarbonate, as detailed below: (1) Same as (1) in Example 1.

[0080] (2) Production steps: 1. Raw material premixing: Isosorbide, diphenyl carbonate, and sodium methoxide are mixed in a ratio of 1:1.02:10. -5 The molar ratio of the ingredients is fed into the melting vessel and heated to 90°C to completely melt them.

[0081] 2. Continuous Feeding: The molten raw material is continuously fed into the top of the thin-film evaporator via a metering feed pump. Based on the area of ​​the thin-film evaporator reactor, the processing capacity of isosorbide in the low-temperature prepolymerization section is 3.2 mol / m³. 2 / h, the central shaft speed of the thin film evaporator is 150r / min.

[0082] 3. Segmented reaction: The temperature control of each segment of the thin film evaporator is as follows: low temperature prepolymerization segment 100℃, using a three-bladed symmetrical scraper; medium temperature reaction segment 180℃, using a spiral scraper with a propulsion angle of 5°; high temperature polycondensation segment 250℃, using a spiral scraper with a propulsion angle of 8°; the vacuum separation unit maintains the vacuum degree in the evaporator at 10Pa and extracts the phenol and small molecule byproducts generated in the reaction in real time.

[0083] 4. Extrusion Molding: The polymerization product is injected into a twin-screw extruder via a gear metering pump, while p-methoxyphenol chain terminator is added simultaneously. The molar ratio of the chain terminator to bisphenol A is 10:1. -5 1. The extruder speed is 200 r / min, the extrusion temperature is controlled at 250℃, and the product is granulated by a pelletizer to obtain polycarbonate granules.

[0084] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 28,000, the molecular weight distribution index is 1.7, and the impact strength is 84 kJ / m. 2 .

[0085] Example 6 A continuous preparation apparatus and method for isosorbide-based polycarbonate, as detailed below: (1) Same as (1) in Example 1.

[0086] (2) Production steps: 1. Raw material premixing: Isosorbide, diphenyl carbonate, and sodium methoxide are mixed in a ratio of 1:1.00:10. -7 The molar ratio of the ingredients is fed into the melting vessel and heated to 90°C to ensure complete melting and uniform mixing.

[0087] 2. Continuous Feeding: The molten raw material is continuously fed into the top of the thin-film evaporator via a metering feed pump. Based on the area of ​​the thin-film evaporator reactor, the processing capacity of isosorbide in the low-temperature prepolymerization section is 4.0 mol / m². 2 / h, the central shaft speed of the thin film evaporator is 180r / min.

[0088] 3. Segmented reaction: The temperature control of each segment of the thin film evaporator is as follows: low temperature prepolymerization segment 90℃, using a three-bladed symmetrical scraper; medium temperature reaction segment 150℃, using a spiral scraper with a propulsion angle of 1°; high temperature polycondensation segment 220℃, using a spiral scraper with a propulsion angle of 5°; the vacuum separation unit maintains the vacuum degree in the evaporator at 300Pa and extracts the phenol and small molecule byproducts generated in the reaction in real time.

[0089] 4. Extrusion Molding: The polymerization product is injected into a twin-screw extruder via a gear metering pump, while p-methoxyphenol chain terminator is added simultaneously. The molar ratio of the chain terminator to bisphenol A is 10:1. -3 1. The extruder speed is 200 r / min, the extrusion temperature is controlled at 220℃, and the product is obtained by pelletizing by a pelletizer.

[0090] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 16,000, the molecular weight distribution index is 1.9, and the impact strength is 78 kJ / m. 2 .

[0091] Comparative Example 1 (without staged reaction) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: (1) Same as (1) in Example 1.

[0092] (2) Production steps: 1. Raw material premixing: Same as in Example 1.

[0093] 2. Continuous feeding: Same as in Example 1.

[0094] 3. Single-stage reaction: Same as in Example 1, except that the temperature of each stage of the thin-film evaporator is kept consistent and controlled at 280°C.

[0095] 4. Extrusion molding: Same as in Example 1.

[0096] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 13,000, the molecular weight distribution index is 2.8, and the impact strength is 54 kJ / m. 2 .

[0097] Comparative Example 2 (segmented reaction, no scraper used) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0098] 2. Continuous feeding: Same as in Example 1.

[0099] 3. Segmented reaction: Same as in Example 1, except that each segment of the reaction does not have a rotating scraper.

[0100] 4. Extrusion molding: Same as in Example 1.

[0101] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 2500, the molecular weight distribution index is greater than 10, and the impact strength is 24kJ / m. 2 .

[0102] Comparative Example 3 (segmented reaction, with scrapers at the same angle) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0103] 2. Continuous feeding: Same as in Example 1.

[0104] 3. Segmented reaction: Same as in Example 1, except that each segment uses the same two-bladed vertical scraper.

[0105] 4. Extrusion molding: Same as in Example 1.

[0106] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 13,000, the molecular weight distribution index is 4.2, and the impact strength is 56 kJ / m. 2 .

[0107] Comparative Example 4 (segmented reaction, with scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0108] 2. Continuous feeding: Same as in Example 1.

[0109] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 6° is used in the intermediate temperature reaction section and a spiral scraper with a propulsion angle of 3° is used in the high temperature polycondensation section.

[0110] 4. Extrusion molding: Same as in Example 1.

[0111] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 27,000, the molecular weight distribution index is 2.8, and the impact strength is 74 kJ / m. 2 .

[0112] Example 7 (Performing a segmented reaction and setting scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0113] 2. Continuous feeding: Same as in Example 1.

[0114] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 1° is used in the intermediate temperature reaction section.

[0115] 4. Extrusion molding: Same as in Example 1.

[0116] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 26,000, the molecular weight distribution index is 1.9, and the impact strength is 88 kJ / m. 2 .

[0117] Example 8 (Performing a segmented reaction and setting scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0118] 2. Continuous feeding: Same as in Example 1.

[0119] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 5° is used in the intermediate temperature reaction section.

[0120] 4. Extrusion molding: Same as in Example 1.

[0121] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 23,000, the molecular weight distribution index is 1.7, and the impact strength is 86 kJ / m. 2 .

[0122] Comparative Example 5 (segmented reaction, with scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0123] 2. Continuous feeding: Same as in Example 1.

[0124] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 6° is used in the intermediate temperature reaction section.

[0125] 4. Extrusion molding: Same as in Example 1.

[0126] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 22,000, the molecular weight distribution index is 1.7, and the impact strength is 83 kJ / m. 2 .

[0127] Comparative Example 6 (segmented reaction, with scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0128] 2. Continuous feeding: Same as in Example 1.

[0129] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 0.5° is used in the intermediate temperature reaction section.

[0130] 4. Extrusion molding: Same as in Example 1.

[0131] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 26,500, the molecular weight distribution index is 2.1, and the impact strength is 79 kJ / m. 2 .

[0132] Example 9 (Performing a segmented reaction and setting scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0133] 2. Continuous feeding: Same as in Example 1.

[0134] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 5° is used in the high-temperature polycondensation stage.

[0135] 4. Extrusion molding: Same as in Example 1.

[0136] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 25,500, the molecular weight distribution index is 1.7, and the impact strength is 88 kJ / m. 2 .

[0137] Example 10 (Performing a segmented reaction and setting scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0138] 2. Continuous feeding: Same as in Example 1.

[0139] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 10° is used in the high-temperature polycondensation stage.

[0140] 4. Extrusion molding: Same as in Example 1.

[0141] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 21,000, the molecular weight distribution index is 1.5, and the impact strength is 90 kJ / m. 2 .

[0142] Comparative Example 7 (segmented reaction, with scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0143] 2. Continuous feeding: Same as in Example 1.

[0144] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 4° is used in the high-temperature polycondensation stage.

[0145] 4. Extrusion molding: Same as in Example 1.

[0146] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 27,000, the molecular weight distribution index is 2.3, and the impact strength is 84 kJ / m. 2 .

[0147] Comparative Example 8 (segmented reaction, with scrapers at different angles) A continuous preparation apparatus and method for bisphenol A type polycarbonate, as detailed below: 1. Raw material premixing: Same as in Example 1.

[0148] 2. Continuous feeding: Same as in Example 1.

[0149] 3. Segmented reaction: Same as in Example 1, except that a spiral scraper with a propulsion angle of 12° is used in the high-temperature polycondensation stage.

[0150] 4. Extrusion molding: Same as in Example 1.

[0151] (3) Product testing: The number average molecular weight of the obtained polycarbonate product is 18,000, the molecular weight distribution index is 1.4, and the impact strength is 82 kJ / m. 2 .

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A continuous polycarbonate production apparatus, characterized in that, It includes a raw material pretreatment unit, a vertically arranged thin-film evaporator, a vacuum separation unit, an extrusion molding unit, and a control system. The outlet of the raw material pretreatment unit is connected to the inlet of the thin film evaporator, and the outlet of the thin film evaporator is connected to the inlet of the extrusion molding unit. The extrusion molding unit also includes a chain terminator inlet. The thin-film evaporator is connected to the vacuum separation unit; The interior of the thin-film evaporator is divided into a low-temperature prepolymerization section, a medium-temperature reaction section, and a high-temperature polycondensation section from top to bottom along the material flow direction. A central shaft is set inside the thin-film evaporator, and scrapers are connected to the central shaft. The scrapers in the low-temperature prepolymerization section are two- or three-bladed symmetrical scrapers perpendicular to the reactor wall. The scrapers in the medium-temperature reaction section are downward-propelling spiral scrapers with a propulsion angle of 1 to 5°. The scrapers in the high-temperature polycondensation section are downward-propelling spiral scrapers with a propulsion angle of 5 to 10°.

2. The continuous polycarbonate production apparatus according to claim 1, characterized in that, The temperature of the low-temperature prepolymerization section is 80~150℃, the temperature of the medium-temperature reaction section is 150~220℃, and the temperature of the high-temperature polycondensation section is 220~300℃.

3. The continuous polycarbonate production apparatus according to claim 1, characterized in that, The height-to-diameter ratio of the thin-film evaporator is 3~8:

1.

4. The continuous polycarbonate production apparatus according to claim 1, characterized in that, The rotational speed of the central shaft is 30~300 r / min.

5. A continuous preparation method for polycarbonate, characterized in that, The continuous polycarbonate production apparatus according to any one of claims 1 to 4 comprises the following steps: The dihydroxy compound, diphenyl carbonate, and alkaline catalyst are mixed in the raw material pretreatment unit to obtain a mixture; The mixture is continuously fed into the top of the thin film evaporator and passes through the low-temperature prepolymerization section, the medium-temperature reaction section and the high-temperature polycondensation section from top to bottom to carry out the polymerization reaction. The polymerization reaction includes prepolymerization, medium-temperature reaction and high-temperature polycondensation carried out in sequence to obtain the polymerization product and other products. The other products are extracted and separated in real time by the vacuum separation unit. The polymer product and chain terminator are end-capped in the extrusion molding unit to obtain polycarbonate.

6. The continuous preparation method of polycarbonate according to claim 5, characterized in that, Based on the feed rate of the dihydroxy compound and the contact area between the compound and the material inside the thin-film evaporator, the processing capacity of the low-temperature prepolymerization section is 2~4 mol / m³. 2 The processing capacity of the mesophilic reaction section is 2~4 mol / m³ / h. 2 The high-temperature polycondensation section has a processing capacity of 1~3 mol / m³ / h. 2 / h.

7. The continuous preparation method of polycarbonate according to claim 5 or 6, characterized in that, The molar ratio of the diphenyl carbonate to the dihydroxy compound is 1~1.05:

1.

8. The continuous preparation method of polycarbonate according to claim 5 or 6, characterized in that, The molar ratio of the alkaline catalyst to the dihydroxy compound is 10. -7 ~10 -5 :

1.

9. The continuous preparation method of polycarbonate according to claim 5 or 6, characterized in that, The molar ratio of the chain terminator to the dihydroxy compound is 10. -5 ~10 -3 :

1.

10. The continuous preparation method of polycarbonate according to claim 5 or 6, characterized in that, The dihydroxy compound includes one or more of bisphenol A, isosorbide, 1,4-butanediol, and 1,4-cyclohexanediethanol.

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