CN116603430B

CN116603430B - An apparatus and method for preparing liquid crystal polymers

Info

Publication number: CN116603430B
Application number: CN202310378085.6A
Authority: CN
Inventors: 金纪阳; 朱文祥; 赵晨霞
Original assignee: Zhejiang Hailide New Material Co ltd; Hailide New Material Research Shanghai Co ltd
Current assignee: Zhejiang Hailide New Material Co ltd; Hailide New Material Research Shanghai Co ltd
Priority date: 2023-04-07
Filing date: 2023-04-07
Publication date: 2025-11-04
Anticipated expiration: 2043-04-07
Also published as: CN116603430A

Abstract

This application discloses an apparatus and method for preparing a liquid crystal polymer. The apparatus includes a devolatilization reactor, a reheater, a polymerization reactor, and an acylation reactor. The liquid phase outlet of the acylation reactor is connected to the feed inlet of the devolatilization reactor. The gas phase outlets of the acylation reactor, the devolatilization reactor, and the polymerization reactor are all connected to the inlet of the reheater. The outlet of the reheater is connected to the gas phase inlet of the devolatilization reactor, and the liquid phase outlet of the devolatilization reactor is connected to the feed inlet of the polymerization reactor. The method includes: Step 1) Weighing and mixing the reactants, then adding an acylation reagent and a catalyst to dissolve them, obtaining a reaction solution; Step 2) The reaction solution undergoes an acylation reaction in the acylation reactor, followed by devolatilization in the devolatilization reactor, and then enters the polymerization reactor for a polycondensation reaction to obtain a polymer melt; Step 3) Cooling the polymer melt and then crushing and granulating it. This application can effectively avoid homopolymerization.

Description

Preparation device and method of liquid crystal polymer

Technical Field

The application belongs to the technical field of polymerization devolatilization devices, and particularly relates to a preparation device and method of a liquid crystal polymer.

Background

The production of thermotropic liquid crystalline polymers (Liquid Crystal Polymer, LCP) now involves two steps, acylation and polycondensation, the acylation step being the reaction of monomers such as 4-hydroxybenzoic acid with acetic anhydride to convert the phenolic hydroxyl groups to acyloxy groups and produce carboxylic acids as by-products. The polycondensation step is to react the acyloxy group with the carboxyl group to form an ester bond while removing one molecule of carboxylic acid as a by-product. Since the presence of carboxylic acid inhibits the progress of polycondensation reaction, it is necessary to devolatilize the acetylation reaction product to remove carboxylic acid. In the acetylation step, in order to increase the conversion of phenolic hydroxyl groups as much as possible, an acid anhydride of slightly more than 1 equivalent is often used as a reactant. But even so, a small amount of unreacted hydroxyl groups are still present in the reaction mixture. In the existing production process, acetic anhydride (acetic anhydride) is generally used as an acylating agent in view of cost and boiling point, and acetic acid is removed as a by-product, so that acetylation is formed.

The existing devolatilization process of the acetylated product generally comprises the following three steps:

the first is to directly heat up to volatilize most of acetic acid, and introduce acetic acid vapor into a condenser to recover acetic acid. This method has the advantage of simple apparatus, but at the same time has the following drawbacks. First, acetic anhydride is distilled off together, and the conversion rate of the reaction is difficult to be further improved. Secondly, in the simple distillation process, since different monomers in the reaction mixture have different polymerization activities, the monomer 4-acetoxybenzoic acid is easy to homopolymerize, and the homopolymerization phenomenon is aggravated along with the increase of the residence time of the reaction mixture in the temperature range of about 170-220 ℃, which simultaneously causes remarkable difficulty in enlarging the liquid crystal polymer reactor. In addition, in a simple distillation process, different degrees of volatilization are easily formed due to different boiling points of different monomers, so that the molar ratio of the monomers in the reaction mixture is changed. This phenomenon tends to cause problems of reactor gas path blockage and low product molecular weight in the preparation of I-type industrialized liquid crystal polymers involving lower boiling diphenol monomers and higher polymerization temperatures.

The second is to take the help of rectifying tower to take the devolatilization, the reaction mixture is located in the tower bottom, the rectifying tower is utilized to achieve the purpose of selectively separating acetic acid, retaining acetic anhydride and improving the reaction conversion rate. The scheme is mainly used for overcoming the defect of the first scheme in the aspect of reaction conversion rate, and the volatilization of acetic anhydride is reduced by adding a rectifying section, so that the equilibrium forward movement of the acetylation reaction can be promoted. However, the problem of homopolymerization is more serious because the reflux of the rectifying tower has even higher requirement on the heating capacity of the reaction kettle than the first scheme. In addition, as the composition of the reactants is continuously changed in the rectification process, the rectification tower often cannot reach the highest separation efficiency, and the temperature of the tower bottom is difficult to rise in the later stage of rectification because the acetic acid reflowing in the dead volume in the tower is continuously boiled to take away heat.

Thirdly, the reactant is slowly depressurized to remove acetic acid after pressure and temperature are maintained. The scheme is mainly to remedy the defects of the two schemes in initiating homopolymerization, and the scheme is to heat the reaction mixture to a temperature above 220 ℃ under the condition of no acetic acid removal or only a small amount of acetic acid removal, usually to a temperature above 240 ℃, and then to carry out the reaction by removing acetic acid through simple distillation or rectification at a high temperature. The defect of the scheme is mainly that the performance requirement on the reactor is high, and the reactor is required to have certain pressure resistance, so that the investment cost of equipment is increased. Meanwhile, the technology needs to raise the temperature of the acetic acid to high temperature for removal, so that the energy consumption of the process is increased, and the corrosion of the high-temperature acetic acid to equipment is higher than that of the former two schemes. In addition, the technical scheme relates to continuous change of pressure in the kettle, and has difficulty in application in the technology of continuously preparing the liquid crystal polyarylate, and the requirement of continuously preparing the liquid crystal polyarylate is difficult to meet.

Therefore, it is needed to provide a device and a method for preparing a liquid crystal polymer, so as to alleviate the problem that the deacetylation product in the preparation process of the liquid crystal polymer is in a step of deacetylation, and the material is easy to homopolymerize due to long residence time in a heating section.

Disclosure of Invention

In view of the above-mentioned drawbacks or shortcomings of the prior art, the present application is to provide a device and a method for preparing a liquid crystal polymer.

In order to solve the technical problems, the application is realized by the following technical scheme:

the application provides a preparation device of a liquid crystal polymer, which comprises a devolatilization reactor, a reheater, at least one polymerization reactor and at least one acylation reactor, wherein a liquid phase outlet of the acylation reactor is communicated with a feed inlet of the devolatilization reactor, a gas phase outlet of the acylation reactor, a gas phase outlet of the devolatilization reactor and a gas phase outlet of the polymerization reactor are all communicated with an inlet of the reheater, an outlet of the reheater is communicated with a gas phase inlet of the devolatilization reactor, and a liquid phase outlet of the devolatilization reactor is communicated with the feed inlet of the polymerization reactor.

Further, the preparation device of the liquid crystal polymer comprises a reflux section, a rectifying section and a stripping section which are sequentially arranged in a shell, wherein a feed inlet is arranged between the rectifying section and the stripping section, a gas phase outlet is arranged at the upper part of the reflux section, and a gas phase inlet and a liquid phase outlet are arranged at the lower part of the stripping section.

Further, the preparation device of the liquid crystal polymer comprises a plate tower or a packed tower.

Further, the device for preparing the liquid crystal polymer further comprises a dissolution kettle, wherein an outlet of the dissolution kettle is communicated with a feed inlet of the acylation reactor.

Further, in the device for preparing a liquid crystal polymer, a stirrer is arranged in the acylation reactor and/or the dissolution kettle.

Further, the liquid crystal polymer preparation device further comprises a condenser and a recovery tank, wherein the inlet of the condenser is communicated with the gas phase outlet of the devolatilization reactor and the inlet of the reheater, and the outlet of the condenser is communicated with the recovery tank.

The application also provides a preparation method of the liquid crystal polymer, which adopts the preparation device of the liquid crystal polymer, and comprises the following steps:

step 1), weighing and mixing reactants, and then adding an acylating reagent and a catalyst for dissolution to obtain a reaction solution;

Step 2), the reaction solution undergoes an acylation reaction through an acylation reactor, and then enters a polymerization reactor for polycondensation reaction after devolatilization through a devolatilization reactor to obtain a polymer melt;

step 3) cooling the polymer melt, and then crushing and granulating.

Further, according to the preparation method of the liquid crystal polymer, the temperature of the material in the acylation reactor is 100-160 ℃.

Further, in the preparation method of the liquid crystal polymer, the temperature of the feed inlet of the devolatilization reactor is 120-180 ℃.

Further, in the preparation method of the liquid crystal polymer, the temperature of the feed inlet of the polymerization reactor is more than or equal to 220 ℃.

Compared with the prior art, the application has the following technical effects:

compared with the prior art, the method has the advantages that the residence time of the method in a homopolymerization temperature zone is shorter, the homopolymerization phenomenon is effectively relieved, the reheater is used for reheating the acylation reactor and the acetic acid steam generated in the devolatilization reactor to form overheated acetic acid steam, the overheated acetic acid steam is then introduced into the devolatilization reactor, the devolatilization is continuously carried out at the high temperature of the overheated acetic acid steam, the partial pressure of the gas-phase acetic acid is larger, the homopolymerization phenomenon is restrained, and meanwhile, the effects of energy conservation and consumption reduction are also achieved.

The application can continuously feed and continuously discharge, is suitable for a semi-continuous or full-continuous process for preparing the liquid crystal polymer, can adopt normal pressure in the reaction process, can adopt inert inorganic nonmetallic materials such as glass or ceramic and the like in the devolatilization reactor, has lower construction cost compared with a strategy of adopting pressurizing to retain acetic acid to avoid homopolymerization, and has lower difficulty in operation and design compared with the prior art because the temperature change is mainly carried out in the devolatilization reactor and the operation temperature of other reaction devices is basically kept constant.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:

FIG. 1 is a schematic view of an apparatus for preparing a liquid crystal polymer according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a simulation apparatus of a devolatilization reactor according to example 4 of the present application;

In the figure, a dissolution kettle 1, a first acylation reactor 2, a second acylation reactor 3, a devolatilization reactor 4, a reflux section 5, a rectifying section 6, a stripping section 7, a condenser 8, a recovery tank 9, a reheater 10, a first steam pump 11, a second steam pump 12, a polymerization reactor 13, a stirring paddle 14, a first tower section 15, a second tower section 16, a third tower section 17, a thermometer 18, a heat insulation layer 19, a straight connector 20, a Y-shaped three-way connector 21, a first injection pump 22, a second injection pump 23 and a reflux condenser 24 are shown.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

As shown in FIG. 1, one embodiment of the application provides a liquid crystal polymer preparation device, which comprises a devolatilization reactor 4, a reheater 10, at least one polymerization reactor 13 and at least one acylation reactor, wherein a liquid phase outlet of the acylation reactor is communicated with a feed inlet of the devolatilization reactor 4, a gas phase outlet of the acylation reactor, a gas phase outlet of the devolatilization reactor 4 and a gas phase outlet of the polymerization reactor 13 are all communicated with an inlet of the reheater 10, an outlet of the reheater 10 is communicated with a gas phase inlet of the devolatilization reactor 4, and a liquid phase outlet of the devolatilization reactor 4 is communicated with a feed inlet of the polymerization reactor 13.

In this example, the number of the acylation reactors is set to two and the number of the polymerization reactors 13 is set to three, and a person skilled in the art is motivated to increase or decrease the number thereof adaptively. The first acylation reactor 2 and the second acylation reactor 3 are communicated in parallel, three polymerization reactors 13 are communicated in series, reactants enter from a feed inlet of the first acylation reactor 2 and a feed inlet of the second acylation reactor 3, a liquid phase outlet of the first acylation reactor 2, a liquid phase outlet of the second acylation reactor 3 and a feed inlet of the devolatilization reactor 4 are communicated, a gas phase outlet of the first acylation reactor 2, a gas phase outlet of the second acylation reactor 3 and a gas phase outlet of the devolatilization reactor 4 are all communicated with an inlet of a reheater 10, an outlet of the reheater 10 is communicated with a gas phase inlet of the devolatilization reactor 4, a liquid phase outlet of the devolatilization reactor 4 is communicated with a feed inlet of the polymerization reactor 13, and a gas phase outlet of the polymerization reactor 13 is communicated with an inlet of the reheater 10. Through the arrangement, the reactant is rapidly devolatilized by the devolatilization reactor 4, and compared with the prior art, the residence time of the embodiment in a homopolymerization temperature zone is shorter, so that the homopolymerization phenomenon is effectively relieved, the acid vapor generated in the acylation reactor and the devolatilization reactor 4 is reheated by the reheater 10 to form superheated acetic acid vapor, and then the superheated acetic acid vapor is introduced into the devolatilization reactor 4, and the devolatilization is continuously performed by the high temperature of the superheated acetic acid vapor, so that the partial pressure of the gas-phase acetic acid is larger, the homopolymerization phenomenon is restrained, and the effects of energy conservation and consumption reduction are achieved.

Optionally, a first steam pump 11 is arranged between the gas phase outlet of the devolatilization reactor 4 and the inlet of the reheater 10 to facilitate steam circulation.

Optionally, a second steam pump 12 is provided between the gas phase outlet of the polymerization reactor 13 and the inlet of the reheater 10 to facilitate steam circulation.

The preparation device of the liquid crystal polymer further comprises a dissolution kettle 1, wherein the outlet of the dissolution kettle 1 is communicated with the feed inlet of the acylation reactor. The dissolution vessel 1 is used for metering, mixing and dissolving the reaction materials.

In this embodiment, the outlet of the dissolution vessel 1 is in communication with the feed inlet of the first acylation reactor 2 and the feed inlet of the second acylation reactor 3. The aromatic hydroxycarboxylic acid, the diphenol monomer, the acylating agent and the catalyst are weighed and then added into a dissolution kettle 1, and the dissolution kettle 1 is used for mixing the materials and preheating to prepare a uniform reactant solution. When the polymerization reaction involves an insoluble dicarboxylic acid monomer such as terephthalic acid, it is preferable that the above dicarboxylic acid monomer is directly fed into the polymerization reactor 13 after devolatilizing the reaction mixture, so as to avoid deposition of the insoluble terephthalic acid in the devolatilization reactor 4 and the acylation reactor. After the dissolution of the reactants is completed, the materials are uniform and clear solution, and the solution flows into the feed inlet of the first acylation reactor 2 and the feed inlet of the second acylation reactor 3 from the outlet of the dissolution kettle 1 to carry out acylation reaction.

Optionally, stirring paddles 14 are arranged in the acylation reactor and/or the dissolution kettle 1, which is beneficial to the full reaction of reactants.

Preferably, the stirring paddle 14 of the dissolution kettle 1 adopts a plate frame type or anchor type stirring paddle 14.

Alternatively, the acylation reactor comprises a batch reactor or a continuous reactor.

Preferably, the acylation reactor body employs a reaction vessel with heat exchange coils, tubes or fins.

Preferably, the acylation reactor is further provided with condensing equipment so as to facilitate the condensation and recycling of the acetic acid.

In this example, the primary function of the first and second acylating reactors 2 and 3 is to acylate the monomer with the anhydride to convert the phenolic hydroxyl groups to acyloxy groups. The method is characterized in that a stirring and heat transfer system is arranged according to the low viscosity characteristic of the reaction materials, and the method has larger heat transfer capacity compared with the configuration without built-in heat exchange fins or coils on the inner optical wall of a common polycondensation kettle. In this example, in order to ensure the continuity of the feed to the devolatilization reactor 4 and the polymerization reactor 13, the acylation reactor employs a first acylation reactor 2 and a second acylation reactor 3 which are arranged in parallel. In order to remove the heat of reaction and reduce the devolatilization load of the devolatilization reactor 4, part of the acetic acid may be evaporated in the first acylation reactor 2 and the second acylation reactor 3. However, in order to avoid homopolymerization due to shift of equilibrium, the removal of acetic acid in the first acylation reactor 2 and the second acylation reactor 3 should not exceed 50% of acetic acid produced by the acylation reaction. Because of the large vaporization heat of acetic acid, it is difficult to remove all the generated acetic acid by only the heat carried by the superheated acetic acid in the polymerization reactor 13, so that auxiliary heat is required, or the superheated feed is required, or a small amount of acetic acid is removed in advance, so that the removed acetic acid can be pumped into the reheater 10 for reheating via the first steam pump 11.

Specifically, the liquid crystal polymer preparation device further comprises a condenser 8 and a recovery tank 9, wherein the inlet of the condenser 8 is communicated with the gas phase outlet of the devolatilization reactor 4 and the inlet of the reheater 10, and the outlet of the condenser 8 is communicated with the recovery tank 9.

In this example, the acetic acid portion removed by the acylation reactor is condensed by a condenser 8 and recovered in a recovery tank 9 to be treated as a by-product.

The devolatilization reactor 4 comprises a reflux section 5, a rectifying section 6 and a stripping section 7 which are sequentially arranged in a shell, wherein a feed inlet is arranged between the rectifying section 6 and the stripping section 7, a gas phase outlet is arranged at the upper part of the reflux section 5, and a gas phase inlet and a liquid phase outlet are arranged at the lower part of the stripping section 7.

In this example, the acetylation reaction mixture was fed from the feed inlet of the devolatilization reactor 4, i.e., from the middle of the devolatilization reactor 4, and above the feed inlet of the devolatilization reactor 4 was a reflux section 5 and a rectifying section 6, and below the feed inlet was a stripping section 7. The purpose of reflux section 5 is to produce acetic acid reflux and to control the reflux flow so that the anhydride and volatile monomers are flushed back. The rectification section 6 is used for intercepting and separating volatile monomers, acetic anhydride and other heavier components from acetic acid, one of the purposes of the rectification section is to reflux acetic anhydride into a reaction mixture to increase the conversion rate of phenolic hydroxyl groups in materials, and in addition, in a process involving volatile monomers, particularly diphenol monomers and volatile catalysts, the rectification section 6 is also used for refluxing the materials to avoid the deviation of the content of the reaction catalyst and the proportion of functional groups of the monomers caused by the volatilization of the materials. The stripping section 7 serves to provide a sufficiently large gas-liquid contact area to allow rapid devolatilization of the reactants without initiating substantial homopolymerization of the acetylated monomers. The devolatilized monomers after devolatilization flow into the feed inlet of the polymerization reactor 13 through the liquid phase outlet of the devolatilization reactor 4 for condensation reaction.

Optionally, the rectifying section 6 includes, but is not limited to, a tray column or a packed column.

Alternatively, when the rectifying section 6 adopts a plate column, the number of the plates is 2 to 100, and preferably, the number of the plates of the rectifying section 6 is 4 to 50, such as 25.

In this embodiment, the rectifying section 6 adopts a packed tower in consideration of corrosiveness of acetic acid-containing medium, and is used in combination with inert nonmetallic packing such as ceramic rings, glass springs and the like.

Alternatively, the stripping section 7 includes, but is not limited to, a plate column, a packed column, a falling film reactor, a tubular structure reactor, a shell-and-tube structure reactor, or a flat plate structure reactor for gas-liquid exchange by increasing the surface area. Of course, those skilled in the art will be motivated to adopt a vertical or inclined arrangement for the tubular, tubular or flat plate structure.

Alternatively, when the stripping section 7 adopts a plate tower, the number of the plates is 2-100, and preferably, the number of the plates of the stripping section 7 is 5-50, such as 30.

In this embodiment, considering the corrosiveness of the acetic acid-containing material, the stripping section 7 adopts a packed tower and is used in combination with inert nonmetallic fillers, such as ceramic rings, glass springs and the like. In addition, the packing is in the form of annular random packing or monolithic structured packing with larger pores, and the resistance of the packing layer is controlled on the premise of ensuring that the reaction liquid has enough specific surface area when flowing through the stripping section 7, so that the blocking condition is avoided.

Optionally, the devolatilization reactor 4 is heated by convection heating, conduction heating and/or radiation heating, wherein the convection heating comprises but is not limited to heating by convection of high-temperature gas, the conduction heating comprises but is not limited to heating by heat conduction oil or electric heat on the wall surface, and the radiation heating comprises but is not limited to using built-in microwave or infrared heating device.

In this embodiment, superheated acetic acid vapor is adopted for convection heating, acetic acid vapor from the polymerization reactor 13 is introduced into the reheater 10 through the second vapor pump 12 via the gas phase outlet of the polymerization reactor 13, and the shortage of flow rate is complemented by the acetic acid vapor generated by the devolatilization reactor 4 and the acylation reactor conveyed by the first vapor pump 11. The acetic acid steam flows into the reheater 10 for heating after being mixed, so that superheated acetic acid steam with stable temperature and flow rate is obtained, and flows into the gas phase inlet of the devolatilization reactor 4 through the outlet of the reheater 10.

Through the arrangement, the devolatilization reactor 4 rapidly removes volatile matters and improves the temperature of materials, so that the materials rapidly reach the polycondensation reaction state with low acetic acid content and high temperature, and the homopolymerization phenomenon in the heating process is reduced.

Alternatively, the polymerization reactor 13 includes, but is not limited to, at least one continuous reactor or batch-tank reactor.

Preferably, the continuous reactor is a horizontal twin screw continuous reactor.

In this embodiment, three continuous reactors are used as the polymerization reactor 13, and a person skilled in the art is motivated to adaptively increase or decrease the number of the reactors. In this example, three continuous reactors were connected in series, and the temperature and vacuum of the continuous reactors were successively increased according to the conversion rate which became higher in the reaction. Another function of the polymerization reactor 13 in this embodiment is to provide the devolatilization reactor 4 with the desired acetic acid vapor.

In this embodiment, the reaction product obtained in the polymerization reactor 13 is a melt, which is extruded by a melt pump or screw, and finally cooled by a water tank, crushed and granulated.

The application also provides a preparation method of the liquid crystal polymer, which adopts the preparation device of the liquid crystal polymer, and the method comprises the following steps:

Step 2), the reaction solution undergoes an acylation reaction through an acylation reactor, and then enters a polymerization reactor 13 for a polycondensation reaction after undergoing a devolatilization through a devolatilization reactor 4 to obtain a polymer melt;

step 3) cooling the polymer melt, and then crushing and granulating.

In this example, the preparation method is directed to thermotropic liquid crystalline polyarylates, particularly type I and type II liquid crystalline polyarylates.

Specifically, the reactants are those conventionally used in the manufacture of liquid crystal polyarylates, known to those skilled in the art, and include the use of aromatic hydroxycarboxylic acid monomers, or the use of aromatic hydroxycarboxylic acid monomers, diacid monomers, and diphenol monomers. The two reactants can be selected by one skilled in the art as desired, with the addition of the diacid monomer and the diphenol monomer to maintain the balance of total carboxyl groups and total hydroxyl groups.

Specifically, the aromatic hydroxycarboxylic acid monomer comprises hydroxybenzoic acid, hydroxynaphthoic acid and/or isomers thereof.

Specifically, the diacid monomer comprises phthalic acid, diphthalic acid, naphthalene dicarboxylic acid and/or isomers thereof.

Specifically, the diphenol monomer comprises hydroquinone, resorcinol, dihydroxydiphenyl ether, bisphenol A, biphenol and/or isomers thereof.

Specifically, the acylating agent includes an acid anhydride; preferably, the acylating agent is acetic anhydride.

Optionally, the catalyst comprises metal salts, ionic liquids, sulfonic acids and/or organic bases.

Optionally, the metal salts include, but are not limited to, zinc salts and potassium salts.

Specifically, the temperature of the material in the dissolution kettle 1 is less than or equal to 110 ℃ so as to avoid self-acceleration of the acylation reaction. When the materials are completely dissolved, the retention time in the dissolution kettle 1 is not more than 20min.

The method comprises the steps of carrying out an acylation reaction on a material in a reactor, wherein the temperature of the material in the acylation reactor is 100-160 ℃, preferably the temperature of the material in the acylation reactor is 100-150 ℃, the retention time of the material is 10 min-3 h, and preferably the retention time is 10 min-2.5 h. The conversion rate of phenolic hydroxyl in the reactant in the acetylation reaction at the stage is not lower than 98%, partial acetic acid can be removed in the acetylation process, but the amount of the removed acetic acid is not more than 0.5mol/mol of the reactant.

Specifically, the temperature of the feed inlet of the devolatilization reactor 4 is 120-180 ℃, and preferably, the temperature of the feed inlet of the devolatilization reactor 4 is 140-160 ℃. Specifically, the temperature of the liquid phase outlet of the devolatilization reactor 4 is 220 ℃ or higher, and preferably 235 ℃ or higher. The amount of acetic acid removed during the stay of the material in the devolatilization reactor 4 is not less than 0.45mol/mol of reactant, the acetic acid content at the liquid phase outlet of the devolatilization reactor 4 is not more than 10mol%, and the dimer and above oligomer content is not more than 20mol%. The average thickness of the material during the residence in the devolatilization reactor 4 is not higher than 10mm, preferably not higher than 2mm. The residence time does not exceed 600 seconds, preferably the residence time does not exceed 150 seconds.

Specifically, the temperature of the feed inlet of the polymerization reactor 13 is 220 ℃ or higher, the discharge temperature varies with the kind of the produced material, and is generally at least 20 ℃ higher than the melting temperature of the material. The total residence time of the materials is 10-120 min.

From the above description, it can be seen that the following technical effects are achieved:

Compared with the prior art, the method has the advantages that the residence time of the method in a homopolymerization temperature zone is shorter, and the homopolymerization phenomenon is effectively relieved;

According to the application, the reheater 10 is utilized to reheat the acetic acid steam generated in the acylation reactor and the devolatilization reactor 4 to form superheated acetic acid steam, and then the superheated acetic acid steam is introduced into the devolatilization reactor 4, and the devolatilization is continuously carried out by utilizing the high temperature of the superheated acetic acid steam, so that the partial pressure of the gas-phase acetic acid is large, the inhibition of the homopolymerization phenomenon is facilitated, and meanwhile, the effects of energy conservation and consumption reduction are also achieved;

the application can continuously feed and discharge, and is suitable for semi-continuous or full-continuous preparation of liquid crystal polymer;

The reaction process of the application can be carried out at normal pressure, the devolatilization reactor 4 can be made of inert inorganic nonmetallic materials such as glass or ceramic, and the construction cost is lower than that of adopting a strategy of pressurizing and retaining acetic acid to avoid homopolymerization;

The temperature change of the application is mainly in the devolatilization reactor 4, the rest reaction devices basically keep the operation temperature constant, and the operation and design difficulties are lower than those of the prior art.

In order to make the technical solution and technical effects of the present application more clearly understood by those skilled in the art, the following description will be made with reference to specific embodiments. In particular by a laboratory simulation device.

The sources of the reaction raw materials for the following examples are as follows:

The p-hydroxybenzoic acid (HBA)/6-hydroxy-2-naphthoic acid (HNA) monomer is polymer grade, more than 99.5 percent, zhejiang holy chemical company;

acetic anhydride, analytical grade (AR), 99%, national drug;

Acetic acid, AR,99.5%, national medicine;

catalyst zinc acetate, 1000ppm.

Example 1

This example relates to the preparation of an acetylation reaction mixture.

This example was carried out at normal pressure and HBA 2mol (276 g), HNA 0.5mol (94 g), acetic anhydride 1.05 equivalent (2.625 mol,268 g), organic base catalyzed 1000ppm (0.38 g relative to solid material) were placed in a 1000ml round bottom flask, followed by a condenser. After nitrogen protection, the mixture was stirred on an electric mantle and heated to 140 ℃. Due to the exothermic effect of the acetylation reaction, the material begins to boil and part of the acetic acid is distilled off. The reaction mixture was incubated at 140℃for 1 hour for use. The reaction was sampled and detected using Nuclear Magnetic Resonance (NMR), specifically using deuterated methanol solvents, and the results are shown in table 1 below.

Example 2

This example differs from example 1 in that the reaction mixture is incubated at 120℃for 2 hours.

Example 3

This example differs from example 1 in that the reaction mixture is incubated at 160℃for 30 minutes.

Table 1 composition of reaction mixture after acetylation reaction of examples 1 to 3

In the table, ABA is 1-acetoxy-4-benzoic acid, and ANA is 2-acetoxy-6-naphthoic acid.

The content of each of the monomer and oligomer of HBA and HNA derivatives in the table was obtained by integrating the peak areas of the characteristic NMR, and the content of acetic anhydride was calculated by calculating the peak areas of methyl acetate due to hydrolysis during sample preparation. The acetic acid fraction is derived from methanolysis of acetic anhydride and is obtained by subtracting the acetic anhydride content from the acetic acid content obtained from the peak area.

Example 4

This example relates to the preparation of devolatilizing monomers.

In this embodiment, as shown in fig. 2, the first tower section 15 and the third tower section 17 are each a rectifying column filled with glass spring packing, the inside is filled with glass spring packing, the lengths are 300mm each, the second tower section 16 is a thorn-shaped glass rectifying column, the lengths are 500mm, and the glass spring packing with a height of about 2cm is piled up at the top end to uniformly distribute the fluid. Between the first 15 and second 16 tower sections is a straight connector 20 with a branch nozzle, the acetylation reaction mixture is placed in a glass injection pump insulated by an electrothermal jacket, and the first injection pump 22 is used for injection from the branch nozzle. The upper part of the first tower section 15 is a thermometer 18 and a reflux condenser 24. The reflux ratio of the reaction is roughly controlled by adjusting the height of the heat-insulating layer 19 at the upper part of the first tower section 15, so that a small amount of reflux in the tower is ensured. The bottom of the second tower section 16 is connected with the flask through a Y-shaped three-way connector 21 for collection. The other outlet of the three-way joint is connected with the third tower section 17, and acetic acid is pumped into the other end of the third tower section 17 by using the second injection pump 23, so that the effect of providing acetic acid steam is achieved. The second tower section 16, the third tower section 17 and the straight connector 20 are all heat-traced by using glass fiber electric heating belts. The temperature of the first tower section 15 is 260 ℃ measured by a sensor at the bottom of the third tower section 17, the temperature of the first tower section 16 is 160 ℃ measured by a sensor at the top of the second tower section, and the first tower section 15 is insulated in a mode of wrapping an insulating material without active heating. A thermometer 18 is provided at the top of the first column section 15 to detect the overhead vapor temperature. The remaining acetic acid, except for a small amount of reflux, is discharged from the top end of the first column section 15 in the form of saturated vapor and is condensed and collected through a condenser tube. The monomer material flowing through the second column section 16 is then collected in a bottom product collection bottle for cooling and temperature is measured by a temperature sensor at the bottom of the second column section 16 for polymerization.

Experiments were performed using 200g of the reaction mixture prepared in example 1, the pumping rate of the material in the experiment being 1.5ml/min and the pumping rate of acetic acid being 5.2ml/min. The sensor of the third tower section 17 shows that the temperature of acetic acid discharged is 259-260 ℃, the temperature of a devolatilization tower feed inlet is 158-161 ℃, the tower top temperature is kept at 118-119 ℃, and the tower bottom temperature of the second tower section 16 fluctuates at 235-242 ℃. The material pumping was completed in a total time of about 33 minutes. The bottom mass was sampled and subjected to NMR detection using specifically deuterated methanol solvent, the results are shown in table 2 below.

Examples 5 to 8

Examples 5 to 8 differ from example 4 in that the experiments were carried out using the reaction mixtures obtained in example 2, and examples 5 to 8 differ in that the devolatilization was carried out using different experimental conditions, with particular reference to table 2 below.

Example 9

This example differs from example 4 in that experiments were performed using the reactant mixture obtained in example 2.

Example 10

This example differs from example 4 in that an experiment was performed using the reactant mixture obtained in example 3.

Comparative example 1

The comparative example relates to the preparation of devolatilizing monomers, in particular to a kettle type rectification method.

In the comparative example, the working condition of the kettle type rectification flow is simulated by combining glass instruments.

200G of the reaction mixture is placed in a 500ml three-neck flask, a mechanical stirring device is arranged at the middle opening, a rectifying column with the height of 300mm is inserted into one side opening, glass spring packing is arranged in the rectifying column, nitrogen is introduced into the other side opening to keep inert atmosphere, and a thermometer is inserted into the rectifying column to control the temperature. The temperature of the distillate was monitored by a thermometer provided at the top of the rectification column. The flask was heated by an electric jacket, and the temperature of the electric jacket was raised at a temperature of about 1 ℃ per minute from 140 ℃. And monitoring the temperature of distillate at the tower top, and controlling the temperature to be about 118-119 ℃ all the time, and if the temperature is higher than 120 ℃, reducing the heating power of the electric jacket. The reaction mixture in the three-necked flask was sampled and analyzed after 110 minutes until the jacket temperature reached 240 ℃.

Comparative example 2

The present comparative example relates to the preparation of devolatilizing monomers, in particular by simple rectification.

In the comparative example, the working condition of a kettle type simple rectification process is simulated by using a glass instrument combination.

200G of reaction mixture is placed in a 500ml three-neck flask, a mechanical stirring device is arranged at the middle opening, a common distillation head is inserted into one side opening, then nitrogen is introduced into the other side opening of acetic acid recovered by a straight condensing tube to keep inert atmosphere, and a thermometer is inserted for temperature control. The temperature of the distillate was monitored by a thermometer provided at the top of the rectification column. The flask was heated by an electric jacket, and the temperature of the electric jacket was raised at a temperature of about 1 ℃ per minute from 140 ℃. The reaction mixture in the three-necked flask was sampled and analyzed after 95min until the jacket temperature reached 240 ℃.

Table 2 experimental conditions and product compositions of examples 4 to 10 and comparative examples 1 and 2

Example 11

This example shows melt polycondensation of devolatilized monomers produced in the manner of example 4.

50G of the devolatilized monomer produced in example 4 was reheated to 240℃for melting, then warmed to 340℃at a rate of 2℃/min, and kept under stirring until a viscous stringy melt was present. The melt was removed and analyzed for melt properties by Differential Scanning Calorimeter (DSC), with specific product properties see table 3 below.

Example 12

This example differs from example 11 in that the devolatilizing monomer employed is the product of example 5.

Example 13

This example differs from example 11 in that the devolatilizing monomer employed is the product of example 6.

Example 14

This example differs from example 11 in that the devolatilizing monomer employed is the product of example 7.

Example 15

This example differs from example 11 in that the devolatilizing monomer employed is the product of example 8.

Example 16

This example differs from example 11 in that the devolatilizing monomer employed is the product of example 9.

Example 17

This example differs from example 11 in that the devolatilizing monomer employed is the product of example 10.

Comparative example 3

The difference between this comparative example and example 11 is that the devolatilizing monomer used is the product of comparative example 1.

Comparative example 4

The difference between this comparative example and example 11 is that the devolatilizing monomer used is the product of comparative example 2.

TABLE 3 product Properties of examples 11 to 17 and comparative examples 3 and 4

From the above examples, the present application can effectively avoid homopolymerization occurring in the devolatilization step and its adverse effect on the properties of the final polymerization product.

In the description of the present application, unless explicitly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may, for example, be fixedly connected, detachably connected, or integrally formed, mechanically connected, electrically connected, directly connected, indirectly connected through an intervening medium, or in communication between two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present application, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "left", "right", etc., azimuth or positional relationship are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description and simplification of operations, and do not indicate or imply that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.

The above embodiments are only for illustrating the technical scheme of the present application, but not for limiting the same, and the present application is described in detail with reference to the preferred embodiments. It will be understood by those skilled in the art that various modifications and equivalent substitutions may be made to the technical solution of the present application without departing from the spirit and scope of the technical solution of the present application, and it is intended to cover the scope of the claims of the present application.

Claims

1. A preparation device of a liquid crystal polymer is characterized by comprising a devolatilization reactor, a reheater, at least one polymerization reactor and at least one acylation reactor, wherein a liquid phase outlet of the acylation reactor is communicated with a feed inlet of the devolatilization reactor, a gas phase outlet of the acylation reactor, a gas phase outlet of the devolatilization reactor and a gas phase outlet of the polymerization reactor are all communicated with an inlet of the reheater, an outlet of the reheater is communicated with a gas phase inlet of the devolatilization reactor, and a liquid phase outlet of the devolatilization reactor is communicated with the feed inlet of the polymerization reactor.

2. The device for preparing the liquid crystal polymer according to claim 1, wherein the devolatilization reactor comprises a reflux section, a rectifying section and a stripping section which are sequentially arranged in a shell, a feed inlet is arranged between the rectifying section and the stripping section, a gas phase outlet is arranged at the upper part of the reflux section, and a gas phase inlet and a liquid phase outlet are arranged at the lower part of the stripping section.

3. The apparatus for producing a liquid-crystalline polymer according to claim 2, wherein the rectifying section comprises a tray column or a packed column.

4. A liquid crystal polymer production apparatus according to any one of claims 1 to 3, further comprising a dissolution vessel, an outlet of which communicates with a feed port of the acylation reactor.

5. The apparatus for producing a liquid crystal polymer according to claim 4, wherein a stirrer is provided in the acylation reactor and/or the dissolution tank.

6. The apparatus for producing a liquid-crystalline polymer according to any one of claims 1 to 3, further comprising a condenser and a recovery tank, wherein an inlet of the condenser is in communication with a gas phase outlet of the devolatilization reactor and an inlet of the reheater, and an outlet of the condenser is in communication with the recovery tank.

7. A method for producing a liquid crystal polymer, characterized in that the production of a liquid crystal polymer is carried out using the production apparatus according to any one of claims 1 to 6, comprising the steps of:

step 3) cooling the polymer melt, and then crushing and granulating.

8. The method for preparing a liquid crystal polymer according to claim 7, wherein the material temperature in the acylation reactor is 100-160 ℃.

9. The method for preparing a liquid crystal polymer according to claim 7, wherein the temperature of the feed inlet of the devolatilization reactor is 120-180 ℃.

10. The method for producing a liquid-crystalline polymer according to claim 7, wherein the temperature of the inlet of the polymerization reactor is 220 ℃ or higher.