Search

CN-122006648-A - Continuous preparation method and device for polycarbonate

CN122006648ACN 122006648 ACN122006648 ACN 122006648ACN-122006648-A

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, a vacuum separation unit, an extrusion molding unit and a control system, wherein the film evaporator is internally provided with a low-temperature prepolymerization section, a medium-temperature reaction section and a high-temperature polycondensation section, scraping blades connected to a central shaft are arranged in the film evaporator, the scraping blades of the low-temperature prepolymerization section are two-leaf or three-leaf symmetrical scraping blades perpendicular to the wall of a reactor, the scraping blades of the medium-temperature reaction section are downward pushing type spiral scraping blades with a pushing angle of 1-5 degrees, and the scraping blades of the high-temperature polycondensation section are downward pushing type spiral scraping blades with a pushing angle of 5-10 degrees. The sectional type thin film evaporator is adopted as a reactor, and continuous production of polycarbonate is realized by combining precise sectional temperature control, special scraping blade design, continuous feeding and by-product vacuum separation.

Inventors

  • SHI FENG
  • CUI XINJIANG
  • YUAN HANGKONG
  • QIAN BO
  • HUANG YONGJI
  • WANG BIN
  • HE DONGCHENG

Assignees

  • 中国科学院兰州化学物理研究所

Dates

Publication Date
20260512
Application Date
20260331

Claims (10)

  1. 1. A continuous preparation device for polycarbonate is characterized by comprising 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, The outlet of the raw material pretreatment unit is communicated with the inlet of the thin film evaporator, the outlet of the thin film evaporator is communicated with the inlet of the extrusion molding unit, and the extrusion molding unit further comprises a chain terminator inlet; The thin film evaporator is communicated with the vacuum separation unit; The inside 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 arranged in the thin film evaporator, a scraping blade is connected on the central shaft, the scraping blade of the low-temperature prepolymerization section is a two-blade or three-blade symmetrical scraping blade perpendicular to the wall of the reactor, the scraping blade of the medium-temperature reaction section is a downward pushing type spiral scraping blade with a pushing angle of 1-5 degrees, and the scraping blade of the high-temperature polycondensation section is a downward pushing type spiral scraping blade with a pushing angle of 5-10 degrees.
  2. 2. The continuous polycarbonate production apparatus according to claim 1, wherein the temperature of the low temperature prepolymerization stage is 80 to 150 ℃, the temperature of the medium temperature reaction stage is 150 to 220 ℃, and the temperature of the high temperature polycondensation stage is 220 to 300 ℃.
  3. 3. The continuous polycarbonate production apparatus according to claim 1, wherein the aspect ratio of the thin film evaporator is 3 to 8:1.
  4. 4. The continuous polycarbonate preparation device according to claim 1, wherein the rotation speed of the central shaft is 30-300 r/min.
  5. 5. A continuous production method of polycarbonate, characterized by using the continuous production apparatus of polycarbonate according to any one of claims 1 to 4, comprising the steps of: mixing a dihydroxy compound, diphenyl carbonate and an alkaline catalyst in the raw material pretreatment unit to obtain a mixture; Continuously feeding the mixture into the top of the thin film evaporator, and sequentially passing through the low-temperature prepolymerization section, the medium-temperature reaction section and the high-temperature polycondensation section from top to bottom to perform polymerization reaction, wherein the polymerization reaction comprises sequentially performed prepolymerization, medium-temperature reaction and high-temperature polycondensation to obtain a polymerization product and other products, and the other products are extracted and separated in real time through the vacuum separation unit; And (3) end-capping the polymerization product and the chain terminator in the extrusion molding unit to obtain the polycarbonate.
  6. 6. The continuous production method of polycarbonate according to claim 5, wherein the treatment capacity of the low-temperature prepolymerization stage is 2-4 mol/m 2 /h, the treatment capacity of the medium-temperature reaction stage is 2-4 mol/m 2 /h, and the treatment capacity of the high-temperature polycondensation stage is 1-3 mol/m 2 /h, based on the amount of the dihydroxy compound fed and the contact area between the interior of the thin film evaporator and the material.
  7. 7. The continuous production method of polycarbonate according to claim 5 or 6, wherein the molar ratio of diphenyl carbonate to dihydroxy compound is 1 to 1.05:1.
  8. 8. The continuous production method for polycarbonate according to claim 5 or 6, wherein the molar ratio of the basic catalyst to the dihydroxy compound is 10 -7 ~10 -5 :1.
  9. 9. The continuous production method for polycarbonate according to claim 5 or 6, wherein the molar ratio of the chain terminator to the dihydroxy compound is 10 -5 ~10 -3 :1.
  10. 10. The continuous production method of polycarbonate according to claim 5 or 6, wherein the dihydroxy compound comprises one or more of bisphenol a, isosorbide, 1, 4-butanediol, and 1, 4-cyclohexanedimethanol.

Description

Continuous preparation method and device for polycarbonate Technical Field The invention relates to the technical field of organic polymer synthesis, in particular to a continuous preparation method and device for polycarbonate. Background Polycarbonate (PC) is a thermoplastic engineering plastic with wide application, known for its excellent comprehensive properties, and has been used in various fields such as electronics, home appliances, construction materials, automobile manufacturing, medical equipment, aerospace, optics, and safety equipment. The interfacial polycondensation method using phosgene as raw material is the earliest industrialized production method, and the technology is mature. However, the application of this method has been severely limited due to its environmental pollution. In contrast, the non-phosgene melt transesterification method avoids the use of harmful organic solvents such as highly toxic phosgene, methylene dichloride and the like, is more environment-friendly, and therefore, becomes the first choice technology of newly-built production devices. The existing melt transesterification method for producing polycarbonate mostly adopts batch reaction or multi-kettle serial continuous reaction mode, and is a multi-stage process. The dihydroxy compound and diphenyl carbonate (DPC) were first melted, then an alkaline catalyst was added, and the reaction was carried out under normal pressure. Then, the temperature is raised to 200-230 ℃ and the system is maintained under the condition of reduced pressure (2-4 kPa) so as to promote the pre-polymerization reaction. And finally, the temperature is further increased to 270-300 ℃, and meanwhile, the pressure is reduced to below 100Pa, so that the reaction is continued until polycarbonate is formed. In the latter stage of the polycondensation reaction, long-term exposure to high-temperature environment can cause degradation, disproportionation and crosslinking reaction of the polycarbonate melt chain segment, thereby adversely affecting the product quality. In addition, dihydroxy compounds are susceptible to thermal decomposition at temperatures above 150 ℃, so the choice of reactor and control of residence time is critical for the production of high performance polycarbonates. The traditional process has the following defects that firstly, the temperature control precision in the reaction process is low, the temperature cannot be accurately regulated and controlled according to the requirements of different reaction stages, the reaction rate is unbalanced, the byproduct generation amount is more, the product purity and the molecular weight distribution are influenced, secondly, the material residence time in the reaction system is uneven, the situation of insufficient or excessive local reaction is easy to occur, the product quality stability is reduced, thirdly, the separation efficiency of phenol and micromolecular byproducts generated by the reaction is low, and the mechanical property and the processing property of polycarbonate can be influenced due to the fact that the phenol and micromolecular byproducts remain in the product. Disclosure of Invention In view of the above, the present invention aims to provide a continuous production method and device for polycarbonate. The device can realize the efficient and continuous preparation of the polycarbonate, and improve the quality and stability of the product. In order to achieve the above object, the present invention provides the following technical solutions: The invention provides a continuous preparation device for polycarbonate, which 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, The outlet of the raw material pretreatment unit is communicated with the inlet of the thin film evaporator, the outlet of the thin film evaporator is communicated with the inlet of the extrusion molding unit, and the extrusion molding unit further comprises a chain terminator inlet; The thin film evaporator is communicated with the vacuum separation unit; The inside 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 arranged in the thin film evaporator, a scraping blade is connected on the central shaft, the scraping blade of the low-temperature prepolymerization section is a two-blade or three-blade symmetrical scraping blade perpendicular to the wall of the reactor, the scraping blade of the medium-temperature reaction section is a downward pushing type spiral scraping blade with a pushing angle of 1-5 degrees, and the scraping blade of the high-temperature polycondensation section is a downward pushing type spiral scraping blade with a pushing angle of 5-10 degrees. Preferably, the t