CN112225884B - Method and system for continuously preparing liquid crystal polymer with adjustable molecular structure - Google Patents

Method and system for continuously preparing liquid crystal polymer with adjustable molecular structure Download PDF

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CN112225884B
CN112225884B CN202010936950.0A CN202010936950A CN112225884B CN 112225884 B CN112225884 B CN 112225884B CN 202010936950 A CN202010936950 A CN 202010936950A CN 112225884 B CN112225884 B CN 112225884B
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reaction
screw extrusion
monomer
extrusion device
liquid crystal
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CN112225884A (en
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高敬民
吴煜
金纪阳
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Wison China Investment Co Ltd
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Wison China Investment Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
    • C08G63/065—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids the hydroxy and carboxylic ester groups being bound to aromatic rings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78—Preparation processes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78—Preparation processes
    • C08G63/785—Preparation processes characterised by the apparatus used

Abstract

The invention relates to the technical field of polymer material preparation, in particular to a method and a system for continuously preparing a liquid crystal polymer with an adjustable molecular structure. The method comprises at least the following steps: 1) Subjecting the first acetylation reaction material to multistage series acetylation reaction and/or prepolymerization reaction to provide a first acetylation monomer and/or prepolymer with a degree of polymerization Xn; 2) Performing multistage series acetylation reaction and/or prepolymerization reaction on the second acetylation reaction material to provide a second acetylated monomer and/or a prepolymer with a polymerization degree of X' n; 3) Carrying out polymerization reaction on the first acetylated monomer and/or prepolymer with the polymerization degree of Xn in the step 1) and the second acetylated monomer and/or prepolymer with the polymerization degree of X' n in the step 2), removing small molecules and acetic acid in vacuum, and extruding and granulating to provide the liquid crystal polymer. The invention can realize the regulation and control of molecular structure; meanwhile, the generation of micromolecular by-products and branched chains is inhibited, and the product performance is improved.

Description

Method and system for continuously preparing liquid crystal polymer with adjustable molecular structure
Technical Field
The invention relates to the technical field of polymer material preparation, in particular to a method and a system for continuously preparing a liquid crystal polymer with an adjustable molecular structure.
Background
Thermotropic Liquid Crystal Polymer (TLCP) is used as a high-performance special engineering plastic, and has more and more extensive application in the fields of aerospace, electronic and electrical appliances, small-sized precise thin-wall parts and the like at present due to a series of excellent performances such as high strength, outstanding heat resistance, chemical corrosion resistance, small linear expansion coefficient, low hygroscopicity and excellent electric insulation and the like.
Typical procedures for preparing thermotropic liquid crystalline polymers are generally as follows:
(1) Carrying out acetylation reaction on a reaction monomer, acetic anhydride and a catalyst in a reaction kettle according to a certain proportion;
(2) After the acetylation is finished, heating, melting and polycondensing reaction is carried out, and simultaneously acetic acid and excessive acetic anhydride are distilled off;
(3) And after the reaction system has rod climbing, discharging the produced polymer from the bottom of the kettle in a molten state, introducing the polymer into a water tank for cooling and pelletizing.
At present, the most common method for thermotropic liquid crystal polymers is a melt polymerization method, and the equipment is a batch kettle type reactor. The key to the production of liquid crystal polymer with excellent performance by the melt polymerization method lies in two points: firstly, providing high-purity acetylated monomers with accurate molar ratio, otherwise causing low molecular weight of liquid crystal polymers and influencing mechanical properties of products; secondly, the reaction temperature is strictly controlled, and the mass and heat transfer effects of the materials in the stage after melt polycondensation are improved. Because the viscosity of a reaction system in the post-stage of melt polycondensation is higher, internal parts such as an internal coil and the like are not usually used in the traditional kettle type polymerization reactor, the heat transfer process mainly depends on the kettle wall for heat transfer, but the specific surface area of the kettle type polymerization reactor is smaller, and the temperature rise rate is slow; meanwhile, due to the stirring form of the polymerization kettle type reactor, the materials are not uniformly mixed, particularly, the viscosity of a polymerization system is increased at the later stage of the reaction, the difficulty of mixing the materials is further increased, the local monomer concentration is easily overhigh, the self-polymerization of the aromatic hydroxycarboxylic acid monomer is aggravated, the molecular weight distribution of a polymer product is not uniform, and the processing performance and the mechanical performance are reduced.
In addition, the kettle type polymerization reaction is mostly a one-pot boiling method, on one hand, the continuous production is difficult to realize, and the productivity utilization rate is low; on the other hand, with the higher and higher application requirements of the TLCP on 5G electronic components, how to precisely regulate and control the polymeric molecular structure so as to substantially improve the material properties of injection molding-grade resin, fiber-grade resin and film-grade resin becomes a hot spot of current industry research.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention provides a method and system for continuously preparing liquid crystal polymer with adjustable molecular structure, which can control the polymerization degree of prepolymer by controlling the residence time of materials in a multistage screw extrusion device during melt polycondensation, and simultaneously accurately introduce other structural units, and adjust the feeding amount of the structural monomers, thereby realizing the adjustment of molecular chain structure.
The invention is realized by the following technical scheme:
the invention provides a method for continuously preparing liquid crystal polymer with adjustable molecular structure, which at least comprises the following steps:
1) Performing multistage series acetylation reaction and/or prepolymerization reaction on the first acetylation reaction material to provide a first acetylation monomer and/or a prepolymer with a polymerization degree Xn;
2) Subjecting the second diacetylated reaction material to multistage series acetylation and/or prepolymerization to provide a second diacetylated monomer and/or a prepolymer having a degree of polymerization of X' n;
3) Carrying out polymerization reaction, vacuum removal of small molecules and acetic acid, and extrusion and granulation on the first acetylated monomer and/or prepolymer with the polymerization degree of Xn provided in the step 1) and the second acetylated monomer and/or prepolymer with the polymerization degree of X' n provided in the step 2) to provide a liquid crystal polymer.
In another aspect of the present invention, there is provided a system for continuously preparing a liquid crystal polymer with a controllable molecular structure, which is used in the method of the present invention, comprising: the first multistage microchannel reaction device and the first primary screw extrusion device are sequentially communicated in the material flow direction; the second multi-stage microchannel reaction device and the second one-stage screw extrusion device are sequentially communicated in the material flow direction; the second-stage screw extrusion device, the third-stage screw extrusion device and the fourth-stage screw extrusion device are sequentially communicated in the material flow direction; the second-stage screw extrusion device is communicated with the first-stage screw extrusion device and the second first-stage screw extrusion device respectively.
In the system and the method, the continuous production of the thermotropic liquid crystal polymer is realized by serially using the multi-stage microchannel reactor and the multi-stage screw extrusion device. By adopting the multistage microchannel reactor, high selectivity in the reaction process of the acetylated monomers is realized, the acetylated monomers with high purity are obtained, the acetylation reaction time in the production process of the liquid crystal polymer is greatly reduced, the problem that the escape of volatile monomers influences the molar precision ratio is avoided, and the cost is saved. The polymerization degree of the prepolymer is controlled by controlling the residence time of the materials in the multistage screw extrusion device in the melt polycondensation process, other structural units are accurately introduced, the feeding amount of the structural monomer is adjusted, and the purpose of adjusting the molecular structure is realized. The multi-stage screw extrusion device is adopted for melt polycondensation reaction, so that the defects of poor processing performance and reduced mechanical performance caused by nonuniform molecular weight distribution of a polymer product due to local implosion of the polymer caused by small mass and heat transfer area and poor stirring in a polyester kettle are overcome. In addition, the micro-reactor strengthens the mass transfer and heat transfer effects in the polymerization reaction process, inhibits the generation of small molecular by-products and branched chains, and improves the product performance of the liquid crystal polymer.
Drawings
FIG. 1 is a schematic structural diagram of a system for continuously preparing a liquid crystal polymer with a controllable molecular structure according to an embodiment of the present invention.
FIG. 2 is a schematic structural diagram of a system for continuously preparing a liquid crystal polymer with a controllable molecular structure according to another embodiment of the present invention.
Element numbers in the figures:
1. first multistage microchannel reaction device
2. Second multistage microchannel reaction device
3. First primary screw extrusion device
4. Second-stage screw extrusion device
5. Two-stage screw extrusion device
51. First secondary screw extruder
52. Second two-stage screw extruder
6. Three-stage screw extrusion device
7. Four-stage screw extrusion device
8. First raw material dissolving device
9. First pump body
10. Second raw material dissolving device
11. Second pump body
12. Cleaning device
13. Rectifying tower
14. Condenser
15. Recovery device
16. Water cooling device
17. Grain cutting device
18. Drying device
19. Finished product packaging device
20. Third-stage screw extrusion device
Detailed Description
In the description of the present invention, it should be noted that the structures, the proportions, the sizes, and the like shown in the drawings attached to the present specification are only used for matching with the contents disclosed in the specification, so as to be understood and read by those skilled in the art, and are not used for limiting the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any modifications of the structures, changes of the proportion relation, or adjustments of the sizes, can still fall within the range covered by the technical contents disclosed in the present invention without affecting the efficacy and the achievable purpose of the present invention. While the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the invention and to simplify the description, it is not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation and be operated in a particular manner, and is not to be construed as limiting the invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
The method and system for continuously preparing liquid crystal polymer with controllable molecular structure according to the present invention are described in detail below.
The invention provides a method for continuously preparing a liquid crystal polymer with an adjustable and controllable molecular structure, which comprises the following steps:
1) Performing multistage series acetylation reaction and/or prepolymerization reaction on the first acetylation reaction material to provide a first acetylation monomer and/or a prepolymer with a polymerization degree Xn;
2) Subjecting the second diacetylated reaction material to multistage series acetylation and/or prepolymerization to provide a second diacetylated monomer and/or a prepolymer having a degree of polymerization of X' n;
3) Carrying out polymerization reaction, vacuum removal of small molecules and acetic acid, and extrusion and granulation on the first acetylated monomer and/or prepolymer with the polymerization degree of Xn provided in the step 1) and the second acetylated monomer and/or prepolymer with the polymerization degree of X' n provided in the step 2) to provide a liquid crystal polymer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, step 1) is to carry out multistage series acetylation reaction and/or prepolymerization reaction on a first acetylation reaction material so as to provide a first acetylation monomer and/or a prepolymer with the polymerization degree Xn. The multistage series connection here may mean, for example, that it is carried out in a first multistage microchannel reaction apparatus 1, wherein the first multistage microchannel reaction apparatus 1 comprises a plurality of microreactors connected in series. The reaction can also be carried out after the first multistage microchannel reaction device 1 and the first primary screw extrusion device 3 are connected in series. In general, different reaction times give different products. The acetylation reaction in the first multi-stage microchannel reactor 1 and the first primary screw extruder 3 to provide the first acetylated monomer may be performed by appropriately adjusting the reaction time (for example, controlling the residence time in the first multi-stage microchannel reactor 1 or the first primary screw extruder 3) according to the target molecular structure. Or the residence time in the first primary screw extrusion device 3 is prolonged, the synthesized first acetylated monomers are further pre-polymerized to generate a prepolymer with the polymerization degree Xn, and the prepolymer with the polymerization degree Xn is a small-molecule polymer.
In one embodiment, in step 1), the acetylation reaction temperature is, for example, 120 to 150 ℃,120 to 130 ℃,130 to 140 ℃, or 140 to 150 ℃; the first acetylated monomer can be generated under the conditions of the reaction time of 5-160s, 5-30s, 30-50s, 50-80s, 80-100s, 100-120 s or 120-160 s.
In another embodiment, in step 1), the reaction temperature in the prepolymerization reaction is 200-340 ℃, 200-240 ℃, 240-280 ℃, 280-300 ℃, or 300-340 ℃; the formed first acetylation monomer can be further subjected to preliminary melt polycondensation reaction to generate a prepolymer with the polymerization degree of Xn under the conditions of the reaction time of 120-360s, 120-160s, 160-200s, 200-240s, 240-300 s, or 300-360 s.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the first acetylation reaction material in the step 1) comprises a first monomer raw material, and the first monomer raw material is selected from one or more of hydroxy aromatic carboxylic acid, aromatic diol and aromatic diacid. More specifically, the first monomer starting material is predominantly one or a combination of more of 4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2, 6-naphthalenedicarboxylic acid, 4 '-biphenyldiol, 4' -biphenyldicarboxylic acid, hydroquinone, resorcinol, terephthalic acid, isophthalic acid, and the like.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the first acetylation reaction material in the step 1) further comprises a first catalyst. The first catalyst is selected from acetate of K, ca, mg, zn or Co or ionic liquid. The first catalyst may be used in an amount of 0.001 to 1%,0.001 to 0.01%,0.01 to 0.1%,0.1 to 0.2%,0.2 to 0.3%,0.3 to 0.4%,0.4 to 0.5%,0.5 to 0.6%,0.6 to 0.7%,0.7 to 0.8%,0.8 to 0.9%, or 0.9 to 1% by weight of the total weight of the first acetylated monomer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the first acetylation reaction material in the step 1) further comprises a first acetylation reagent. In one embodiment, the first acetylating agent is acetic anhydride.
Generally, the ratio of the first acetylation reactant materials is precisely controlled according to the target liquid crystal polymer. In the step 1), the molar ratio of the first monomer raw material to the first acetylation reagent (for example, acetic anhydride) is preferably 1.5, and the amount of the first catalyst added is preferably 0.01 to 0.1%,0.01 to 0.05%, or 0.05 to 0.1% of the total weight of the first acetylation monomer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, in the step 1), the solvent is further rectified and condensed in the prepolymerization process under normal conditions, and acetic acid or the unreacted first acetylation reagent is recovered.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the step 2) is to carry out multistage series acetylation reaction and/or prepolymerization reaction on the second diacetylation reaction material so as to provide a second diacetylation monomer and/or a prepolymer with the polymerization degree of X' n. The multistage series connection here may mean, for example, that it is carried out in a second multistage microchannel reaction apparatus 2, wherein the second multistage microchannel reaction apparatus 2 comprises a plurality of microreactors connected in series. The reaction can also be carried out after the second multi-stage microchannel reaction device 2 and the second one-stage screw extrusion device 4 are connected in series. In general, different reaction times give different products. The acetylation reaction in the second multi-stage microchannel reactor 2 and the second one-stage screw extruder 4 to provide the second diacetylated monomer can be carried out with a reasonable adjustment of the reaction time (for example, the residence time in the second multi-stage microchannel reactor 2 or the second one-stage screw extruder 4 can be controlled) according to the target molecular structure. Or prolonging the residence time in the second-stage screw extrusion device 4, and further carrying out prepolymerization reaction on the synthesized second diacetylated monomer to generate a prepolymer with the polymerization degree of X 'n, wherein the prepolymer with the polymerization degree of X' n is a small-molecule polymer.
In one embodiment, in step 2), the temperature for the acetylation reaction is, for example, 120 to 150 ℃,120 to 130 ℃,130 to 140 ℃, or 140 to 150 ℃; the second diacetylated monomer can be generated under the conditions of the reaction time of 5-160s, 5-30s, 30-50s, 50-80s, 80-100s, 100-120 s or 120-160 s.
In another embodiment, in the step 2), the reaction temperature of the multistage series reaction is 200-340 ℃, 200-240 ℃, 240-280 ℃, 280-300 ℃ or 300-340 ℃; the formed second diacetylated monomer can be further subjected to preliminary melt prepolymerization reaction to generate a prepolymer with the polymerization degree of X' n under the conditions of the reaction time of 120-360s, 120-160s, 160-200s, 200-240s, 240-300 s or 300-360 s.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the second diacetylation reaction material in the step 2) comprises a second monomer raw material, and the second monomer raw material is one or a combination of more of hydroxy aromatic carboxylic acid, aromatic diol and aromatic diacid. More specifically, the second monomer raw material is mainly one or more of 4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2, 6-naphthalenedicarboxylic acid, 4 '-biphenol, 4' -biphthalic acid, hydroquinone, resorcinol, terephthalic acid, isophthalic acid and the like. The first monomer raw material and the second monomer raw material are different. Specifically, at least one of the first monomer raw material and the second monomer raw material has a different chemical composition.
In the method for continuously preparing the liquid crystal polymer with the adjustable and controllable molecular structure, the second diacetylation reaction material in the step 2) also comprises a second catalyst. The second catalyst is selected from acetate or ionic liquid of K, ca, mg, zn or Co. The second catalyst may be used in an amount of 0.001 to 1%,0.001 to 0.01%,0.01 to 0.1%,0.1 to 0.2%,0.2 to 0.3%,0.3 to 0.4%,0.4 to 0.5%,0.5 to 0.6%,0.6 to 0.7%,0.7 to 0.8%,0.8 to 0.9%, or 0.9 to 1% by weight of the total weight of the second diacetylated monomer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the second diacetylation reaction material in the step 2) also comprises a second diacetylation reagent. In one embodiment, the second acetylating agent is selected from acetic anhydride.
In general, the ratio of the second acetylating reactant material to the target liquid crystal polymer is precisely controlled. In the step 2), the molar ratio of the second monomer raw material to the second acetylating agent (e.g., acetic anhydride) is preferably 1.5, and the amount of the second catalyst added is preferably 0.01 to 0.1%,0.01 to 0.05%, or 0.05 to 0.1% of the total weight of the second acetylating monomer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, in the step 2), usually, the pre-polymerization reaction can be further rectified, condensed and recycled to obtain acetic acid or unreacted second acetylating reagent.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the step 3) is to perform polymerization reaction on the first acetylated monomer and/or prepolymer with the degree of polymerization Xn provided in the step 1) and the second acetylated monomer and/or prepolymer with the degree of polymerization X' n provided in the step 2), remove small molecules and acetic acid in vacuum, and finally extrude and granulate to obtain the liquid crystal polymer. Specifically, in the polymerization step, the polymerization step is used for further polycondensing the monomers (e.g., first acetylated monomer, second acetylated monomer), the small molecule polymer (e.g., prepolymer with a degree of polymerization Xn, prepolymer with a degree of polymerization X' n) to form a high molecular aromatic polymer and deacidifying. The reaction temperature of the polymerization reaction is 200-340 ℃, 200-240 ℃, 240-280 ℃ or 280-340 ℃; the reaction time is 120-480 s, 120-200s, 200-300s, 300-400 s, or 400-480 s. In the polymerization reaction process, the solvent is further rectified and condensed to recover acetic acid.
In the step 3), in the vacuum removal step, when the system viscosity is high, the generated micromolecules and acetic acid are removed by vacuumizing in the polymerization process, so that the polymerization degree is further improved. The temperature of vacuum removal is 200-340 ℃, 200-240 ℃, 240-280 ℃, or 280-340 ℃; the reaction time is 120-360s, 120-200s, 200-300 s or 300-360 s.
Said step 3), in the extrusion step, is for discharging the high-viscosity polymer. The extrusion temperature is 200-340 ℃, 200-240 ℃, 240-280 ℃ or 280-340 ℃; the reaction time is 120-360s, 120-200s, 200-300 s or 300-360 s.
The invention synthesizes acetylated monomers or controls the polymerization degree of prepolymers by reasonably controlling the reaction time in the step 1) and the step 2), thereby realizing the regulation and control of molecular structure. In step 3):
when the first acetylated monomer and the second acetylated monomer are selected to carry out polymerization, the liquid crystal polymer of ABAB type is prepared.
When the degree of polymerization is selected to be X 3 The polymerization reaction of the prepolymer and the second acetylated monomer produces the AAAB type liquid crystal polymer.
When the first acetylated monomer is selected and the polymerization degree is X' 3 When the prepolymer of (2) is polymerized, a liquid crystal polymer of ABBB type is obtained.
The method for continuously preparing the liquid crystal polymer with the adjustable molecular structure further comprises a post-treatment step, wherein the liquid crystal polymer prepared in the step 3) is subjected to water cooling, grain cutting, drying and finished product packaging.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the molecular structure can be further adjusted and controlled by accurately introducing other polymers or other monomers. And 3) carrying out polymerization reaction, vacuum removal of small molecules and acetic acid, extrusion and granulation on the first acetylated monomer and/or prepolymer with the polymerization degree of Xn provided in the step 1) and the second diacetylated monomer and/or prepolymer with the polymerization degree of X' n provided in the step 2) and other polymers and/or other monomers to provide the liquid crystal polymer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the step 3) is to firstly carry out polymerization reaction on the first acetylated monomer and/or the prepolymer with the polymerization degree of Xn provided by the step 1) and the second acetylated monomer and/or the prepolymer with the polymerization degree of X' n provided by the step 2), and then add any one of the following operation steps;
a. adding an additional polymer or an additional monomer for polymerization;
b. the polymerization is carried out sequentially by adding one other polymer or one other monomer at a time.
Wherein, in some embodiments, the polymer is selected from a prepolymer having a degree of polymerization X "n; the monomer is selected from a third acetylated monomer and/or an aromatic carboxylic acid compound monomer; and the third acetylated monomer and/or the prepolymer with the polymerization degree of X' n are prepared by carrying out multistage series acetylation reaction and/or prepolymerization reaction on the third acetylated reaction material.
In one embodiment, the temperature of the acetylation reaction is, for example, 120 to 150 ℃,120 to 130 ℃,130 to 140 ℃, or 140 to 150 ℃; the third acetylated monomer can be generated under the conditions of the reaction time of 5-160s, 5-30s, 30-50s, 50-80s, 80-100s, 100-120 s or 120-160 s.
In another embodiment, the reaction temperature in the prepolymerization reaction is 200-340 ℃, 200-240 ℃, 240-280 ℃, 280-300 ℃, or 300-340 ℃; the formed third acetylated monomer can be further subjected to preliminary melt polycondensation reaction to generate a prepolymer with the polymerization degree of X' n under the conditions of 120-360s, 120-160s, 160-200s, 200-240s, 240-300 s or 300-360 s of reaction time.
The third acetylation reaction mass comprises a third monomer feed selected from one or more of a hydroxyaromatic carboxylic acid, an aromatic diol, and an aromatic diacid. More specifically, the third monomer raw material is mainly one or more of 4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2, 6-naphthalenedicarboxylic acid, 4 '-biphenyldiol, 4' -biphenyldicarboxylic acid, hydroquinone, resorcinol, terephthalic acid, isophthalic acid and the like. The third monomer raw material is different from the first monomer raw material and the second monomer raw material. Specifically, the third monomer raw material is different from at least one of the first monomer raw material and the second monomer raw material in chemical composition.
The third acetylated reaction mass further comprises a third catalyst, the third catalyst is selected from K, ca, mg, zn or Co acetate or ionic liquid, and the amount of the third catalyst is 0.001-1%, 0.001-0.01%, 0.01-0.1%, 0.1-0.2%, 0.2-0.3%, 0.3-0.4%, 0.4-0.5%, 0.5-0.6%, 0.6-0.7%, 0.7-0.8%, 0.8-0.9%, or 0.9-1% of the total weight of the third acetylated monomer. The third acetylation reaction mass further comprises a third acetylation reagent. For example, the third acylating agent is selected from acetic anhydride. It should be noted that, in specific applications, the first acetylation reaction material, the second acetylation reaction material, and the third acetylation reaction material are selected differently, and the prepared acetylation monomers or prepolymers are also different. Generally, the ratio of the third acetylated reaction material is precisely controlled according to the target liquid crystal polymer. In the step 1), the molar ratio of the third monomer raw material to the third acetylating agent (e.g., acetic anhydride) is preferably 1.5, and the amount of the third catalyst added is preferably 0.01 to 0.1%,0.01 to 0.05%, or 0.05 to 0.1% of the total weight of the monomers.
In the method for continuously preparing the liquid crystal polymer with the controllable molecular structure, the other monomers can also be selected from aromatic carboxylic acid compound monomers, and the aromatic carboxylic acid compound monomers can be selected from one or more of 4,4' -biphenyldicarboxylic acid, terephthalic acid and isophthalic acid.
Specifically, the polymerization reaction may be carried out by adding one other monomer. For example, in the step 3), the first acetylated monomer and/or prepolymer with a polymerization degree Xn provided in the step 1) and the second acetylated monomer and/or prepolymer with a polymerization degree X' n provided in the step 2) are polymerized, and then the aromatic carboxylic acid compound monomer is added for polymerization, the small molecules and acetic acid are removed in vacuum, and extrusion and granulation are performed, so as to provide the liquid crystal polymer.
In one embodiment, the AB type oligomer is prepared by first polymerizing a first acetylated monomer and a second acetylated monomer. Then, the AB type oligomer and the aromatic carboxylic acid compound monomer are subjected to polymerization reaction to prepare the ABCABC type liquid crystal polymer.
In another embodiment, the degree of polymerization is X 3 Polymerizing the prepolymer with a second diacetylated monomer to obtain an AAAB type oligomer, and polymerizing the AAAB type oligomer with an aromatic carboxylic acid compound monomer to obtain the AAABCAABC type liquid crystal polymer.
In another embodiment, the first acetylated monomer is first polymerized with a degree of polymerization of X' 3 The ABBB type oligomer is prepared by the polymerization reaction of the prepolymer, and the ABBBCABBC type liquid crystal polymer is prepared by the polymerization reaction of the ABBB type oligomer and the aromatic carboxylic acid compound monomer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, provided by the invention, other polymer or other monomer is added for polymerization reaction. For example, the polymer is selected from a prepolymer having a degree of polymerization X "n, and the monomer is selected from a third acetylated monomer. And 3) carrying out polymerization reaction on the first acetylated monomer and/or prepolymer with the polymerization degree of Xn provided in the step 1) and the second diacetylated monomer and/or prepolymer with the polymerization degree of X 'n provided in the step 2), then selectively adding a third acetylated monomer and/or prepolymer with the polymerization degree of X' n for carrying out polymerization reaction, removing micromolecules in vacuum, carrying out acetic acid extrusion and granulating, and thus providing the liquid crystal polymer.
In one embodiment, the first acetylated monomer and the second acetylated monomer are polymerized to produce an AB type oligomer. Then, AB type oligomer and a third acetylated monomer are polymerized to prepare ABDABD type liquid crystal polymer.
In another embodiment, the degree of polymerization is X 3 And polymerizing the prepolymer and the second acetylated monomer to prepare the AAAB type oligomer. Then, the AAAB type oligomer and the third acetylated monomer are polymerized to prepare the AAABDAAABD type liquid crystal polymer.
In the method for continuously preparing the liquid crystal polymer with the adjustable molecular structure, provided by the invention, other polymers or other monomers can be added each time to carry out polymerization reaction in sequence. For example, in the step 3), the first acetylated monomer and/or prepolymer with a polymerization degree Xn provided in the step 1) and the second acetylated monomer and/or prepolymer with a polymerization degree X' n provided in the step 2) are polymerized, then the aromatic carboxylic acid compound monomer is added for polymerization, then the third acetylated monomer and/or prepolymer with a polymerization degree X "n is added for polymerization, the small molecules are removed in vacuum, acetic acid is removed, and extrusion and granulation are performed, so as to provide the liquid crystal polymer. Such as ABCDABCD type, etc.
In one embodiment, the AB type oligomer is prepared by first polymerizing a first acetylated monomer and a second acetylated monomer. Then the AB type oligomer and the aromatic carboxylic acid compound monomer are polymerized to prepare the ABC type oligomer. Then carrying out polymerization reaction on the ABC type oligomer and the third acetylated monomer to prepare the ABCDABCD type liquid crystal polymer.
The invention provides a method for continuously preparing a liquid crystal polymer with a controllable molecular structure, and the specific type of the formed liquid crystal polymer can be a polymer formed by blending and polymerizing a plurality of monomers or prepolymers thereof (a plurality of acetylated monomers or prepolymers thereof and aromatic carboxylic acid compound monomers). Specifically, for example, 2 kinds of monomers, 3 kinds of monomers, 4 kinds of monomers, and the like can be mentioned.
In another aspect of the present invention, there is provided a system for continuously preparing a liquid crystal polymer with a controllable molecular structure, comprising:
a first multistage microchannel reaction device 1 and a first primary screw extrusion device 3, which are used for carrying out multistage series acetylation reaction and/or prepolymerization reaction on the first acetylation reaction materials to provide first acetylated monomers and/or prepolymers with a polymerization degree Xn;
a second multi-stage microchannel reaction device 2 and a second stage screw extrusion device 4, which are used for carrying out multi-stage series acetylation reaction and/or prepolymerization reaction on the second diacetylation reaction material so as to provide a second diacetylation monomer and/or a prepolymer with the polymerization degree of X' n;
a secondary screw extrusion device 5 for carrying out polymerization reaction on the first acetylated monomer and/or the prepolymer with the degree of polymerization Xn and the second acetylated monomer and/or the prepolymer with the degree of polymerization X' n; a three-stage screw extrusion device 6 for removing small molecules and acetic acid in vacuum; a four-stage screw extrusion device 7 for extruding and pelletizing.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, as shown in figure 1, a first multistage microchannel reaction device 1 and a first primary screw extrusion device 3 are sequentially communicated in the material flow direction; a second multi-stage microchannel reaction device 2 and a second one-stage screw extrusion device 4 which are communicated in sequence in the material flow direction; a second-stage screw extrusion device 5, a third-stage screw extrusion device 6 and a fourth-stage screw extrusion device 7 which are sequentially communicated in the material flow direction; the second-stage screw extrusion device 5 is respectively communicated with the first-stage screw extrusion device 3 and the second first-stage screw extrusion device 4.
The first multi-stage microchannel reaction device 1, the first primary screw extrusion device 3 and the feed inlet of the secondary screw extrusion device 5 are communicated in sequence; the second multi-stage microchannel reaction device 2, the second primary screw extrusion device 4 and the feed inlet of the secondary screw extrusion device 5 are communicated in sequence; the first multistage microchannel reaction device 1 and the first primary screw extrusion device 3 can be regarded as a first parallel unit, the second multistage microchannel reaction device 2 and the second primary screw extrusion device 4 can be regarded as a second parallel unit, and the first parallel unit and the second parallel unit are connected in parallel and do not interfere with each other in reaction. The first acetylated monomer or prepolymer with the degree of polymerization Xn can be selectively prepared by regulating the residence time of the first primary screw extrusion device 3. Thus, when the first acetylated monomer is produced, the first primary screw extrusion apparatus 3 may be regarded as an acetylation reaction section; the first primary screw extrusion apparatus 3 may be regarded as a prepolymerization stage when a prepolymer having a polymerization degree Xn is produced. And (3) regulating the residence time of the second-stage screw extrusion device 4 to prepare a second diacetylated monomer or a prepolymer with the polymerization degree of X' n. Thus, the second stage screw extrusion apparatus 4 can be considered as an acetylation reaction zone when the second acetylated monomer is formed; the second stage screw extrusion device 4 may be regarded as a prepolymerization section when a prepolymer having a degree of polymerization X' n is formed. The two parallel units are respectively connected with a two-stage screw extrusion device 5 (which can be regarded as a polymerization section), and the first acetylated monomer or prepolymer with the polymerization degree Xn and the second acetylated monomer or prepolymer with the polymerization degree X' n are polymerized in the two-stage screw extrusion device 5. Further, a discharge port of the secondary screw extrusion device 5 is communicated with a tertiary screw extrusion device 6 (which can be regarded as a vacuum section) and a quaternary screw extrusion device 7 (which can be regarded as an extrusion section) in sequence; and a vacuumizing device is arranged on the three-stage screw extrusion device 6. After the polymerization reaction, when the viscosity of the system is high, the generated micromolecules and acetic acid are removed by vacuumizing through a vacuumizing device (such as a vacuum pump) on the three-stage screw extrusion device 6, so that the polymerization degree is further improved, and the molecular weight is improved. Then, the high-viscosity polymer is discharged through a four-stage screw extrusion device 7 to obtain the liquid crystal polymer of the present invention. The invention adopts multi-stage screw extruders in series connection, is used for the melt polycondensation stage, and can perform the deacidification of acetylated monomers and the melt polycondensation reaction of small molecular polymers to form high molecular aromatic liquid crystal polymers, and simultaneously achieve the purpose of adjustable molecular structure by accurately introducing other polymers or monomers.
In the present invention, a plurality of parallel units, for example, 2, 3, 4 units, etc., may be provided according to actual requirements corresponding to different types of liquid crystal polymers in the foregoing method. The system is a molecular structure adjustable device, the molecular structure adjustable device is a plurality of sets of system parallel units, at least two sets of the molecular structure adjustable devices are provided, and the parallel units are specifically a multistage microchannel reaction device (acetylation reaction) and a one-stage screw extrusion device which are connected in series. The first parallel unit is connected in series with the second-stage screw extrusion device 5, and the remaining parallel units are connected in series with the other-stage screw extrusion devices, preferably, the second-stage screw extrusion device 5.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the acetylation monomer is synthesized or the polymerization degree of the prepolymer is controlled by reasonably controlling the residence time of the raw materials in a multi-stage micro-channel reaction device (a first multi-stage micro-channel reaction device 1 or a second multi-stage micro-channel reaction device 2 and the like) and a first-stage screw extrusion device (a first one-stage screw extrusion device 3 or a second one-stage screw extrusion device 4 and the like), so that the adjustment of the molecular structure is realized.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the secondary screw extrusion device 5 comprises a plurality of screw extruders connected in series. For example, the extruder comprises a plurality of first secondary screw extruders 51, second secondary screw extruders 52 and third secondary screw extruders which are communicated end to end. The feed inlet of the first secondary screw extruder 51 is communicated with the discharge outlet of the first primary screw extruder 3 or the second primary screw extruder 4. The discharge hole of the third second-stage screw extruder is communicated with the feed inlet of the third-stage screw extruder 6.
When in use, as shown in fig. 1, when the number of parallel units is 2:
in a specific embodiment, by controlling the reaction time, a first acetylated monomer is generated by a first multistage microchannel reaction device 1 and a first primary screw extrusion device 3, a second acetylated monomer is generated by a second multistage microchannel reaction device 2 and a second primary screw extrusion device 4, and the first acetylated monomer and the second acetylated monomer enter a second stage screw extrusion device 5 together for polymerization reaction to prepare the ABAB type liquid crystal polymer.
In another embodiment, the reaction time is controlled byA multistage microchannel reaction device 1 and a first primary screw extrusion device 3 generate a polymerization degree X 3 The prepolymer (2) is processed by a second multi-stage microchannel reaction device 2 and a second stage screw extrusion device 4 to generate a second diacetylated monomer, and the polymerization degree is X 3 The prepolymer and the second diacetylated monomer enter a secondary screw extrusion device 5 together for polymerization reaction to prepare the AAABAAAB type liquid crystal polymer.
In another embodiment, by controlling the reaction time, a first acetylated monomer is produced by the first multistage microchannel reactor 1 and the first primary screw extruder 3, and a polymerization degree of X 'is produced by the second multistage microchannel reactor 2 and the second primary screw extruder 4' 3 The first acetylated monomer and the polymerization degree of X' 3 The prepolymer is put into a secondary screw extrusion device 5 together for polymerization reaction to prepare the ABBB type liquid crystal polymer.
When the number of the parallel units is 3, as shown in FIG. 2:
in a specific embodiment, by controlling the reaction time, a first acetylated monomer is generated by the first multi-stage microchannel reactor 1 and the first primary screw extruder 3, a second acetylated monomer is generated by the second multi-stage microchannel reactor 2 and the second primary screw extruder 4, and the first acetylated monomer and the second acetylated monomer enter the first secondary screw extruder 51 together for reaction to prepare the AB-type oligomer. Then, the AB type oligomer and the aromatic carboxylic acid compound monomer or the third acetylated monomer formed in the third stage screw extruder 20 enter the second stage screw extruder 52 to be polymerized, and the ABCABC type or ABDABD type liquid crystal polymer is prepared.
In another embodiment, the polymerization degree X is generated by controlling the reaction time through the first multistage microchannel reaction device 1 and the first primary screw extrusion device 3 3 The prepolymer is processed by a second multi-stage micro-channel reaction device 2 and a second first-stage screw extrusion device 4 to generate a second diacetylated monomer, and the polymerization degree is X 3 The prepolymer and the second diacetylated monomer are fed into a first secondary screw extruder 51 together for reaction to prepare the AAAB type oligomerA compound (I) is provided. Then, the AAAB type oligomer and the aromatic carboxylic acid compound monomer or the third acetylated monomer formed in the third stage screw extruder 20 are fed into the second stage screw extruder 52 to be polymerized to prepare the AAABCAABC type or AAABDAAABD type liquid crystal polymer.
In another embodiment, by controlling the reaction time, a first acetylated monomer is produced by the first multistage microchannel reactor 1 and the first primary screw extruder 3, and a polymerization degree of X 'is produced by the second multistage microchannel reactor 2 and the second primary screw extruder 4' 3 The polymerization degree of the prepolymer of (1) is X' 3 The prepolymer and the first acetylated monomer enter a first secondary screw extruder 51 together to react, and the ABBB type oligomer is prepared. Then, the ABBB type oligomer and the aromatic carboxylic acid compound monomer or the third acetylated monomer formed in the third primary screw extruder 20 enter the second secondary screw extruder 52 to perform polymerization reaction, and the abbbbcabbbc type or abbbbdabbd type liquid crystal polymer is prepared.
When there are 4 parallel units:
in a specific embodiment, a first acetylated monomer is first generated by controlling the reaction time through a first multistage microchannel reaction device 1 and a first primary screw extrusion device 3, a second acetylated monomer is generated by a second multistage microchannel reaction device 2 and a second primary screw extrusion device 4, and the first acetylated monomer and the second acetylated monomer enter a first secondary screw extruder 51 together for reaction to prepare the AB-type oligomer. Then, the AB type oligomer is reacted with the aromatic carboxylic acid compound monomer formed in the third-stage screw extruder 20 in the second-stage screw extruder 52 to prepare the ABC type oligomer. Then, a third acetylated monomer formed by ABC type oligomer in a fourth-stage screw extruder is subjected to polymerization reaction in a third-stage screw extruder to prepare the ABCDABCD type liquid crystal polymer.
In the system for continuously preparing the liquid crystal polymer with the adjustable and controllable molecular structure, the system further comprises a first raw material dissolving device 8 for dissolving the first acetylation reaction materials, and the first raw material dissolving device 8 can be a dissolving tank, for example. The first raw material dissolving device 8 is communicated with the first multi-stage microchannel reaction device 1; a first pump body 9 is arranged on a communicating pipeline between the first raw material dissolving device 8 and the first multi-stage microchannel reaction device 1, materials are fully dissolved in the first raw material dissolving device 8, and the first pump body 9 is used for pushing first acetylation reaction materials into the first multi-stage microchannel reaction device 1 to carry out acetylation reaction. The first pump body 9 may be a advection pump, for example. The propelling speed of the first pump body 9 is 5-200 ml/min, 5-50 ml/min, 50-100 ml/min, 100-150 ml/min or 150-200 ml/min.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the first multistage microchannel reaction device 1 can be regarded as an acetylation system and comprises a plurality of microreactors connected in series. A plurality of microreactors are connected in series, and the continuous preparation of the raw materials of precursor acetylated monomers for synthesizing liquid crystal polymers can be realized. In the present invention, all microreactors used may be, for example, microreactors in cn202010387936. X. In one embodiment, the first multi-stage microchannel reactor device 1 comprises a first primary microreactor, a first secondary microreactor and a first tertiary microreactor which are communicated in sequence. The discharge hole of the first raw material dissolving device 8 is communicated with the feed inlet of the first primary microreactor. And a discharge hole of the first tertiary microreactor is communicated with a feed inlet of the first primary screw extrusion device 3. The temperature of the material flowing through each stage of microreactor is gradually increased, and the heating temperature is preferably 120-150 ℃. More specifically, for example, the first primary microreactor is heated at a temperature of 110 to 120 ℃. The heating temperature of the first and second-stage microreactors is 120-130 ℃. The heating temperature of the first three-stage microreactor is 130-150 ℃. The reaction residence time of the materials in each stage of microreactor is gradually shortened, and the reaction time is preferably 5-160 s. For example, the first primary microreactor has a reaction time of 30 to 40s. The reaction time of the first second-stage microreactor is 20-30 s. The reaction time of the first three-stage microreactor is 10-20 s.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure provided by the present invention, as shown in fig. 1, the system further comprises a second raw material dissolving device 10 for dissolving the second diacetylation reaction material, and the second raw material dissolving device 10 may be a dissolving tank, for example. The second raw material dissolving device 10 is communicated with the second multistage microchannel reaction device 2; and a second pump body 11 is arranged on a pipeline between the second raw material dissolving device 10 and the second multistage microchannel reaction device 2, the materials are fully dissolved in the second raw material dissolving device 10, and the second pump body 11 is used for pushing the second diacetylation reaction materials into the second multistage microchannel reaction device 2 for acetylation reaction. The second pump body 11 may be a advection pump, for example. The propelling speed of the second pump body 11 is 5-200 ml/min, 5-50 ml/min, 50-100 ml/min, 100-150 ml/min, or 150-200 ml/min.
In the system for continuously preparing the liquid crystal polymer with the adjustable and controllable molecular structure, the second multi-stage microchannel reaction device 2 comprises a plurality of microreactors which are sequentially communicated, and in one embodiment, the second multi-stage microchannel reaction device 2 comprises a second first-stage microreactor, a second-stage microreactor and a second third-stage microreactor which are sequentially communicated. The feed inlet of the second first-stage microreactor is communicated with the discharge outlet of the second raw material dissolving device 10. And a discharge hole of the second tertiary microreactor is communicated with a feed inlet of the first primary screw extrusion device 3. The temperature of the material flowing through each stage of the microreactor is gradually increased, and the heating temperature is preferably 120-150 ℃. More specifically, for example, the heating temperature of the second-stage microreactor is 110 to 120 ℃. The heating temperature of the second-stage micro-reactor is 120-130 ℃. The heating temperature of the second third-stage microreactor is 130-150 ℃. The reaction residence time of the materials in each stage of microreactor is gradually shortened, and the reaction time is preferably 5-160 s. For example, the reaction time of the second-stage microreactor is 30 to 40s. The reaction time of the second-stage micro-reactor is 20-30 s. The reaction time of the second three-stage micro-reactor is 10-20 s. The reaction temperature and the reaction time range of the first multi-stage microchannel reaction device 1 and the second multi-stage microchannel reaction device 2 are consistent.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, as shown in fig. 1, the system further comprises a cleaning device 12, wherein the cleaning device 12 is communicated with a pipeline between the first raw material dissolving device 8 and the first multistage microchannel reaction device 1; and the cleaning device 12 is communicated with the pipeline between the second raw material dissolving device 10 and the second multistage microchannel reaction device 2. The cleaning device 12 is used for cleaning the residual raw materials in the pipeline and the microreactor when the reaction is finished. The cleaning device 12 may be, for example, a cleaning tank.
In the system for continuously preparing the liquid crystal polymer with the adjustable and controllable molecular structure, the heating modes of the first raw material dissolving device 8, the first multistage microchannel reaction device 1, the second raw material dissolving device 10, the second multistage microchannel reaction device 2 and the cleaning device 12 are not limited, in one embodiment, the first raw material dissolving device 8, the first multistage microchannel reaction device 1, the second raw material dissolving device 10, the second multistage microchannel reaction device 2 and the cleaning device 12 can be heated by heat conducting oil, the corresponding connecting pipelines are all sleeved with heat tracing bands, and the heating temperature can be 120-150 ℃, 120-130 ℃, 130-140 ℃ or 140-150 ℃.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, as shown in fig. 1, a rectifying tower 13, a condenser 14 and a recovery device 15 which are sequentially communicated are arranged on a first primary screw extrusion device 3, a second primary screw extrusion device 4 and a secondary screw extrusion device 5, and the rectifying tower 13 is communicated with the first primary screw extrusion device 3, the second primary screw extrusion device 4 or the secondary screw extrusion device 5. Wherein, the rectifying tower 13, the condenser 14 and the recovery device 15 arranged on the first primary screw extrusion device 3 and the second primary screw extrusion device 4 are used for recovering acetic acid. The rectifying tower 13, the condenser 14 and the recovery device 15 arranged on the secondary screw extrusion device 5 are used for recovering acetic acid. Specifically, the distillate of the first primary screw extrusion device 3 and the second primary screw extrusion device 4 enters a recovery tower after being purified by a rectifying tower 13, each three tower plates of the rectifying tower 13 are provided with a sampling port, through sampling analysis on the distillate, when the distillate hardly contains monomers, the optimal number of the tower plates can be determined, and the number of the tower plates of the rectifying tower 13 is preferably 3-60, 3-10, 10-30, 30-50 or 50-60. The problem that the monomer escapes along with distillate to influence the molar ratio can be greatly avoided by adjusting the optimal number of the tower plates.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the screw diameters of the first primary screw extrusion device 3 and/or the second primary screw extrusion device 4, the secondary screw extrusion device 5, the third-stage screw extrusion device 6 and the fourth-stage screw extrusion device 7 are gradually increased, the length-diameter ratio of the screws is gradually reduced, and the rotating speed of the screws is gradually reduced. The screw diameter from the first-stage screw extrusion device to the fourth-stage screw extrusion device is 16-42 mm, the length-diameter ratio of the screw is preferably 25-85, and the rotation speed of the screw is 80-200 rpm, so that the defect that the fluid flow resistance is increased due to the increase of the viscosity of materials is avoided. More specifically, the screw diameter of the first primary screw extrusion device 3 and/or the second primary screw extrusion device 4 is 16-22, the length-diameter ratio of the screw is 70-85, and the rotation speed of the screw is 170-200. The screw diameter of the secondary screw extrusion device 5 is 22-28, the length-diameter ratio of the screw is 55-70, and the rotating speed of the screw is 140-170. The screw diameter of the three-stage screw extrusion device 6 is 28-36, the length-diameter ratio of the screw is 40-55, and the rotating speed of the screw is 110-140. The screw diameter of the four-stage screw extrusion device 7 is 36-42, the length-diameter ratio of the screw is 25-40, and the rotation speed of the screw is 80-110.
The polycondensation system of the present invention is a multistage screw extrusion apparatus, and as described above, the present invention has functional zones such as a prepolymerization zone, a polymerization zone, a vacuum zone, and an extrusion zone. The prepolymerization section is used for deacidifying the first acetylated monomer and carrying out primary melt polycondensation reaction on the acetylated monomer and the aromatic carboxylic acid compound monomer to obtain a small molecular polymer; the polymerization section is used for further polycondensation reaction of the small molecular polymer to form a high molecular aromatic polymer and deacidification reaction; the vacuum section is used in the polymerization process, and when the viscosity of the system is higher, the generated micromolecules and acetic acid are removed, so that the polymerization degree is further improved; the extrusion section is used to discharge a high viscosity polymer. And the first primary screw extrusion device 3, the second primary screw extrusion device 4, the secondary screw extrusion device 5, the third screw extrusion device 6 and the fourth screw extrusion device 7 respectively comprise one or more screw extruders connected in series so as to ensure that the materials have enough residence reaction time in the screws. In an embodiment, the screw extruder may be selected from the group consisting of a single screw extruder and a twin screw extruder, preferably a twin screw extruder, more preferably a co-rotating intermeshing twin screw extruder. The co-rotating meshed double-screw extruder has larger specific surface area and stirring capacity, improves the heat exchange effect of materials and a reactor, has the special effect of self cleaning, and can improve the production efficiency.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the heating modes of the first primary screw extrusion device 3, the second primary screw extrusion device 4, the secondary screw extrusion device 5, the third-stage screw extrusion device 6 and the fourth-stage screw extrusion device 7 are not particularly limited, in one embodiment, the first primary screw extrusion device 3, the second primary screw extrusion device 4, the second-stage screw extrusion device 5, the third-stage screw extrusion device 6 and the fourth-stage screw extrusion device 7 are all provided with heat-insulating jackets, the heating medium is introduced into the heat-insulating jackets through circulating pumps, the temperature of the jackets is gradually increased, and the temperature of the jackets is 200-340 ℃, 200-240 ℃, 240-280 ℃, 280-300 ℃ or 300-340 ℃.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, which is provided by the invention, as shown in figure 1, the system also comprises a post-treatment device, wherein the post-treatment device comprises a water cooling device 16, a granulating device 17, a drying device 18 and a finished product packaging device 19 which are sequentially communicated, and the discharge end of the four-stage screw extrusion device 7 is communicated with the water cooling device 16. Wherein the water cooling device 16 is used for further water cooling treatment of the liquid crystal polymer, the granulating device 17 is used for further granulating, and drying in the drying device 18 after granulating; after drying, the finished product is packaged in a finished product packaging device 19. The water cooling device 16 may be, for example, a water tank. The dicing device 17 is, for example, a dicing cutter. The drying device is, for example, a dryer. The finished packaging device is for example a packaging machine.
In the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, when the number of the parallel units is 3, the system also comprises a third raw material dissolving device for dissolving the aromatic carboxylic acid compound or a third acylation reaction raw material. The device can also comprise a third multistage microchannel reaction device, and a third pump body is arranged in the third raw material dissolving device and the third multistage microchannel reaction device. The discharge port of the third multistage microchannel reaction device is connected with the feed port of the third one-stage screw extrusion device 20. The cleaning device 12 is communicated with a pipeline between the third raw material dissolving device and the third multistage microchannel reaction device. The number of parallel units is specifically limited to 2 in each apparatus.
When the number of the parallel units is 4, a unit which is the same as the unit added in the parallel unit 3 is added in addition to the three units. And so on. And selecting a plurality of parallel units according to actual needs.
In one embodiment, the present invention can be understood as that the molecular chain structure of the present invention can be controlled mainly as follows: the first acetylation reaction material enters a first multi-stage microchannel reaction device 1 and a first primary screw extrusion device 3 in sequence, and a prepolymer with the polymerization degree of Xn or a first acetylation monomer is obtained by controlling the retention time of the material in the first primary screw extrusion device 3; and the second diacetyl reaction material enters a second multi-stage microchannel reaction device 2 and a second stage screw extrusion device 4, and a prepolymer with the polymerization degree of X' n or a second diacetyl monomer is obtained by controlling the retention time of the material in the second stage screw extrusion device 4. At the moment, the prepolymer with the polymerization degree of Xn and X' n or the first acetylated monomer and the second acetylated monomer enter a secondary screw extruder to be blended and polymerized simultaneously, so that the molecular chain structure can be regulated and controlled.
The invention has the beneficial effects that:
1. according to the method and the system for continuously preparing the liquid crystal polymer with the adjustable and controllable molecular structure, the problem of severe fluctuation of reaction temperature in the process of preparing the acetylated monomer is solved by adopting the multistage microchannel reaction device, the rapid transfer of reaction heat is ensured, and the implosion and the generation of low molecular weight byproducts caused by local overheating of a reaction system are prevented. Meanwhile, the purity of the high-selectivity acetylated monomers is met by accurately adjusting the system reaction temperature of the multistage microchannel reaction device, so that the technical requirement of the high-purity acetylated monomers required in the polycondensation stage of the synthetic liquid crystal polymer is met, and compared with the traditional kettle type acetylated device, the reaction time is greatly reduced, the energy consumption and the investment cost are saved, the labor cost is saved, and the large-scale production can be realized.
2. According to the method and the system for continuously preparing the liquid crystal polymer with the adjustable molecular structure, the multistage screw extrusion device is adopted in the melt polycondensation stage system, so that the stability and the continuity of the whole reaction system are ensured. Compared with the traditional kettle type reactor, the heat exchange requirement of the melt polycondensation stage in the preparation process is met by adjusting the rotating speed, the diameter and the length-diameter ratio of each stage of screw rod device in the multistage screw rod extrusion device, the contact area of materials and the reactor is greatly improved, the effect of mass transfer and heat transfer is enhanced, the melt polycondensation later stage of the traditional kettle type reactor is avoided, and the product performance is finally influenced because the specific surface area of the traditional kettle type reactor is small and the heat transfer effect is poor, so that the local carbonization of the system product is easily caused, the molecular weight distribution is seriously influenced.
3. The polymerization degree of the prepolymer is controlled by controlling the residence time of the materials in the multistage screw extrusion device in the melt polycondensation process, other structural monomers are accurately introduced, and the feeding amount of the structural monomers is adjusted, so that the molecular structure can be regulated and controlled.
4. Compared with the traditional batch kettle type reactor, the liquid crystal polymer process system provided by the invention can realize continuous production, and achieves the purposes of improving the reaction efficiency and enhancing the productivity.
The following examples are provided to further illustrate the advantageous effects of the present invention.
In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, the present invention is further described in detail below with reference to examples. However, it should be understood that the embodiments of the present invention are only for explaining the present invention and not for limiting the present invention, and the embodiments of the present invention are not limited to the embodiments given in the specification. The examples were prepared under conventional conditions or conditions recommended by the material suppliers without specifying specific experimental conditions or operating conditions.
Furthermore, it is to be understood that one or more method steps recited in the present disclosure are not exclusive of other method steps that may also be present before or after the recited combination of steps or that other method steps may also be inserted between the explicitly recited steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.
In the following examples, reagents, materials and instruments used are commercially available unless otherwise specified.
Wherein each screw extrusion device is selected from a co-rotating meshed double screw extruder. Each raw material dissolving device is selected from a dissolving tank.
Example 1
With p-hydroxybenzoic acid (A) and 2-hydroxy-6-naphthoic acid (B) 1 ) As raw material, continuously preparing a structural unit AB 1 AB 1 A liquid crystal polymer of type (I).
As shown in figure 1, 138.13g of p-hydroxybenzoic acid, 0.11g of potassium acetate and 204g of acetic anhydride are added into a first raw material dissolving device 8, after the materials are dissolved, the materials are led into a first multistage micro-reaction device 1 through an advection pump to carry out acetylation reaction, the first multistage micro-reaction device 1 comprises a plurality of micro-reactors connected in series, the reaction time of the materials in each stage of micro-channel is gradually shortened, the heating temperature is gradually increased, the propelling speed of the advection pump is controlled to be 100-120 ml/min, the staying time of the materials in the first multistage micro-reaction device 1 is controlled to be 10-20 s, and the reaction temperature is controlled to be 130-140 ℃; the residence time of the acetylated monomers in the first-stage micro-screw extrusion device 3 is controlled to be 2-10 s, and the heating temperature of the first-stage micro-screw extrusion device 3 is controlled to be 140-150 ℃. The first acetylated monomer is obtained by preparation, and the purity of the first acetylated monomer is more than 99.5%.
188.18g of 2-hydroxy-6-naphthoic acid, 0.15g of potassium acetate and 204g of acetic anhydride were added to the second raw material dissolving device 10. After the materials are dissolved, the materials are led into a second multistage micro-reaction device 2 through an advection pump to carry out acetylation reaction, the second multistage micro-reaction device 2 comprises a plurality of micro-reactors connected in series, the reaction time of the materials in each stage of micro-reactor is gradually shortened, the heating temperature is gradually increased, the propelling speed of the advection pump is controlled to be 100-120 ml/min, the staying time of the materials in the second multistage micro-reaction device 2 is controlled to be 10-20 s, and the reaction temperature is controlled to be 130-140 ℃; the residence time of the acetylated monomers in the second-stage micro screw extrusion device 4 is controlled to be 2-10 s, and the heating temperature of the second-stage screw extrusion device 4 is controlled to be 140-150 ℃. The second acetylated monomer is prepared, and the purity of the first acetylated monomer is more than 99.5 percent.
The first acetylated monomer of the first primary screw extrusion device 2 and the second acetylated monomer of the second primary screw extrusion device 4 simultaneously enter the second-stage screw extrusion device 5 for polymerization reaction, the heating temperature of the second-stage screw extrusion device 5 is controlled to be 200-260 ℃, the rotating speed is 200-300 rpm, and the retention time is 20-120 s. The material enters a three-stage screw extrusion device 6, the heating temperature is controlled to be 250-300 ℃, the rotating speed is 100-200 rpm, and the retention time is 60-150 s. The material enters a four-stage screw extrusion device 7, the heating temperature is controlled to be 280-340 ℃, the rotating speed is 80-160 rpm, and the retention time is 80-200 s.
And cooling the material after passing through the four-stage screw extrusion device by a water tank, and then granulating by a granulator, drying and packaging the finished product.
The liquid crystal polymer with the melting point of 253 ℃ is obtained by DSC test, and the mole number of p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid monomers is 1.
Example 2
With p-hydroxybenzoic acid (A) and 2-hydroxy-6-naphthoic acid (B) 1 ) As raw material, the continuous preparation of the structural unit AAAB 1 AAAB 1 A liquid crystal polymer of type (I).
As shown in figure 1, 138.13g of p-hydroxybenzoic acid, 0.11g of potassium acetate and 204g of acetic anhydride are added into a first raw material dissolving device 8, after the materials are dissolved, the materials are led into a first multistage micro-reaction device 1 through an advection pump to carry out acetylation reaction, the first multistage micro-reaction device 1 comprises a plurality of micro-reactors connected in series, the reaction time of the materials in each stage of micro-channel is gradually shortened, the heating temperature is gradually increased, the propelling speed of the advection pump is controlled to be 100-120 ml/min, the residence time of the materials in the first multistage micro-reaction device 1 is controlled to be 10-20 s, and the reaction temperature is controlled to be 130-140 ℃; the residence time of the acetylated monomers in the first-stage micro-screw extrusion device 3 is controlled to be 15-30 s, the heating temperature of the first-stage micro-screw extrusion device 3 is controlled to be 200-230 ℃, and the first acetylated monomers are obtained through preparation, wherein the purity of the first acetylated monomers is more than 99.5%.
188.18g of 2-hydroxy-6-naphthoic acid, 0.15g of potassium acetate and 204g of acetic anhydride were added to the second raw material dissolving device 10. After the materials are dissolved, the materials are led into a second multistage micro-reaction device 2 through a constant-pressure pump to carry out acetylation reaction, the second multistage micro-reaction device 2 comprises a plurality of micro-reactors connected in series, the reaction time of the materials in each stage of micro-channel is gradually shortened, the heating temperature is gradually increased, the propelling speed of the constant-pressure pump is controlled to be 60-100 ml/min, the staying time of the materials in the second multistage micro-reaction device 2 is controlled to be 10-20 s, and the reaction temperature is controlled to be 130-140 ℃; the residence time of the acetylated monomers in the second-stage micro screw extrusion device 4 is controlled to be 2-10 s, the heating temperature of the second-stage micro screw extrusion device 4 is controlled to be 140-150 ℃, and the polymerization degree X is obtained by preparation 3 The prepolymer of (1).
The polymerization degree of the first acetylated monomer of the first primary screw extrusion device 2 and the polymerization degree of the second primary screw extrusion device 4 are X 3 The prepolymer simultaneously enters a secondary screw extrusion device 5 for polymerization reaction, the heating temperature of the secondary screw extrusion device 5 is controlled to be 230-260 ℃, the rotating speed is 200-300 rpm, and the retention time is 20-120 s. The material enters a three-stage screw extrusion device 6, the heating temperature is controlled to be 250-300 ℃, the rotating speed is 100-200 rpm, and the retention time is 60-150 s. The material enters a four-stage screw extrusion device 7, the heating temperature is controlled to be 280-340 ℃, the rotating speed is 80-160 rpm, and the retention time is 80-200 s.
And cooling the material after passing through the four-stage screw extrusion device by a water tank, and then granulating by a granulator, drying and packaging the finished product. The liquid crystal polymer with the melting point of 278 ℃ is obtained by DSC test, and the mole number of p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid monomers is 3 by nuclear magnetic hydrogen spectrum analysis test.
Example 3
Comprises p-hydroxybenzoic acid (A) and hydroquinone (B) 2 ) And terephthalic acid (C) as raw materials, and continuously preparing AAB as a structural unit 2 Liquid crystalline polymers of type C.
As shown in figure 2, 138.13g of p-hydroxybenzoic acid, 0.11g of potassium acetate and 204g of acetic anhydride are added into a first raw material dissolving device 8, after the materials are dissolved, the materials are led into a first multistage micro-reaction device 1 through an advection pump to carry out acetylation reaction, the first multistage micro-reaction device 1 comprises a plurality of micro-reactors connected in series, the reaction time of the materials in each stage of micro-channel is gradually shortened, the heating temperature is gradually increased, the propelling speed of the advection pump is controlled to be 100-120 ml/min, the staying time of the materials in the first multistage micro-reaction device 1 is controlled to be 10-20 s, and the reaction temperature is controlled to be 130-140 ℃; the residence time of the acetylated monomers in the first-stage micro-screw extrusion device 3 is controlled to be 15-30 s, the heating temperature of the first-stage micro-screw extrusion device 3 is controlled to be 200-230 ℃, and the polymerization degree X is obtained by preparation 2 The prepolymer of (1).
55.05g of hydroquinone, 0.05g of potassium acetate and 104g of acetic anhydride were added to the second raw material dissolving apparatus 10. After the materials are dissolved, the materials are led into a second multistage micro-reaction device 2 through an advection pump to carry out acetylation reaction, the second multistage micro-reaction device 2 comprises a plurality of micro-reactors connected in series, the reaction time of the materials in each stage of micro-reactor is gradually shortened, the heating temperature is gradually increased, the propelling speed of the advection pump is controlled to be 60-100 ml/min, the staying time of the materials in the second multistage micro-reaction device 2 is controlled to be 10-20 s, and the reaction temperature is controlled to be 130-140 ℃; the residence time of the acetylated monomer in the second-stage micro screw extrusion device 4 is controlled to be 2-10 s, the heating temperature of the second-stage screw extrusion device 4 is controlled to be 140-150 ℃, and the second acetylated monomer with the purity of 99.5% is obtained.
83g of terephthalic acid and 100g of acetic anhydride are added into a third raw material dissolving tank, the materials enter a third-stage screw extrusion device 20, the heating temperature is controlled to be 250-300 ℃, the rotating speed is 100-200 rpm, and the retention time is 60-150 s, so that a third dissolved monomer C dissolved in the acetic anhydride is obtained.
The polymerization degree of the first primary screw extrusion device 2 is X 2 The prepolymer and the second diacetylated monomer of the second primary screw extruder 4 enter a first secondary screw extruder 51 simultaneously for polymerization reaction, the heating temperature of the first secondary screw extruder 51 is controlled to be 230-260 ℃, the rotating speed is 200-300 rpm, and the retention time is 20-120 s. To obtain a polymerization degree of AAB 2 A small molecule prepolymer of (2).
The polymerization degree of AAB obtained by the first secondary screw extruder 51 2 The small molecular prepolymer and a third dissolved monomer C obtained in a third primary screw extrusion device 20 enter a second secondary screw extruder 52 for polymerization to obtain a polymer with AAB degree of polymerization 2 A polymer of C.
The material enters a three-stage screw extrusion device 6, the heating temperature is controlled to be 280-340 ℃, the rotating speed is 80-160 rpm, and the retention time is 80-200 s.
The material enters a four-stage screw extrusion device 7, the heating temperature is controlled to be 280-340 ℃, the rotating speed is 80-160 rpm, and the retention time is 80-200 s.
And (4) cooling the material through a water tank after passing through a four-stage screw extrusion device, then pelletizing the material by a pelletizer, drying, and packaging the finished product. The liquid crystal polymer with the melting point of 278 ℃ is obtained through DSC test, and the molar number of p-hydroxybenzoic acid, hydroquinone and terephthalic acid monomers is 2.
While the present invention has been described with reference to the preferred embodiments, it will be apparent to those skilled in the art that the present invention can be practiced without departing from the spirit and scope of the invention by modifying or otherwise appropriately combining the features of the present invention. It is expressly intended that all such similar substitutes and modifications which would be obvious to those skilled in the art are deemed to be within the spirit, scope and content of the invention.

Claims (16)

1. A method for continuously preparing liquid crystal polymer with adjustable molecular structure, which is used by a multistage micro-channel reactor and a multistage screw extrusion device in series, and at least comprises the following steps:
1) Performing multistage series acetylation reaction and/or prepolymerization reaction on the first acetylation reaction material to provide a first acetylation monomer and/or a prepolymer with a polymerization degree Xn; the reaction temperature of the prepolymerization reaction in the step 1) is 200 to 230 ℃; the reaction time is 20 to 260s, so as to provide a prepolymer with the polymerization degree of Xn;
2) Performing multistage series acetylation reaction and/or prepolymerization reaction on the second acetylation reaction material to provide a second acetylated monomer and/or a prepolymer with a polymerization degree of X' n; the reaction temperature of the prepolymerization reaction in the step 2) is 200 to 230 ℃; the reaction time is 20 to 260s, so as to provide a prepolymer with the polymerization degree of X' n;
3) Carrying out polymerization reaction, vacuum removal of small molecules and acetic acid, and extrusion and granulation on the first acetylated monomer and/or prepolymer with the polymerization degree of Xn provided in the step 1) and the second acetylated monomer and/or prepolymer with the polymerization degree of X' n provided in the step 2) to provide a liquid crystal polymer.
2. The method for continuously preparing a liquid crystal polymer with controllable molecular structure according to claim 1, wherein the method further comprises any one or more of the following conditions:
a1 The reaction temperature of acetylation reaction in the step 1) is 120 to 150 ℃; the reaction time is 5 to 160s, so as to provide a first acetylated monomer;
a2 The first acetylation reaction material in the step 1) comprises a first monomer raw material which is one or more of hydroxyl aromatic carboxylic acid, aromatic diol and aromatic diacid;
a3 The first acetylation reaction mass in step 1) further comprises a first catalyst selected from acetates of K, ca, mg, zn or Co or ionic liquids; the dosage of the first catalyst is 0.001 to 1 percent of the total weight of the first acetylated monomer;
a4 The first acetylation reaction mass of step 1) further comprises a first acetylation reagent;
a5 The reaction temperature of acetylation reaction in the step 2) is 120 to 150 ℃; the reaction time is 5 to 160s, so as to provide a second diacetylated monomer;
a6 The second acetylation reaction material in the step 2) comprises a second monomer raw material which is one or more of hydroxy aromatic carboxylic acid, aromatic diol and aromatic diacid;
a7 The second acetylation reaction mass in step 2) further comprises a second catalyst selected from acetate salts of K, ca, mg, zn or Co or ionic liquids; the dosage of the second catalyst is 0.001 to 1 percent of the total weight of the second diacetylated monomer;
a8 The second acetylating reaction mass of step 2) further includes a second acetylating reagent.
3. The method for continuously preparing a liquid crystal polymer with a controllable molecular structure according to claim 2, wherein the first monomer raw material and the second monomer raw material are different.
4. The method for continuously preparing a liquid crystal polymer with controllable molecular structure according to claim 1, wherein the method further comprises any one or more of the following conditions:
b1 The reaction temperature of the polymerization reaction in the step 3) is 200 to 340 ℃; the reaction time is 120 to 360s;
b2 The temperature for vacuum removal in the step 3) is 200 to 340 ℃; the reaction time is 120 to 360s;
b3 The temperature for extrusion in the step 3) is 200 to 340 ℃; the reaction time is 120 to 360s;
b4 The step 3) further comprises rectifying, condensing and recovering the solvent after the polymerization reaction.
5. The method for continuously preparing liquid crystal polymer with adjustable molecular structure according to claim 1, further comprising a post-treatment step of water cooling, granulating, drying and final product packaging the liquid crystal polymer prepared in step 3).
6. The method for continuously preparing a liquid crystal polymer with a controllable molecular structure according to any one of claims 1 to 5, wherein the step 3) comprises the steps of carrying out polymerization reaction on the first acetylated monomer and/or the prepolymer with the polymerization degree Xn provided in the step 1), the second acetylated monomer and/or the prepolymer with the polymerization degree X' n provided in the step 2) and other polymers and/or other monomers, removing small molecules and acetic acid in vacuum, extruding and cutting into granules to provide the liquid crystal polymer.
7. The method for continuously preparing a liquid crystal polymer with a controllable molecular structure according to claim 6, wherein the step 3) comprises polymerizing the first acetylated monomer and/or prepolymer with a polymerization degree Xn provided in the step 1) with the second acetylated monomer and/or prepolymer with a polymerization degree X' n provided in the step 2), and then selecting any one of the following operation steps;
c1 Adding an additional polymer or an additional monomer to carry out polymerization;
c2 In succession, one additional polymer or one additional monomer is added at a time.
8. The method according to claim 7, wherein the other polymer is selected from the group consisting of a prepolymer having a degree of polymerization of X "n;
the other monomer is selected from a third acetylated monomer and/or an aromatic carboxylic acid compound monomer;
the third acetylated monomer and/or the prepolymer with the polymerization degree of X '' n are prepared by carrying out multistage series acetylation reaction and/or prepolymerization reaction on the third acetylated reaction material.
9. The method for continuously preparing a liquid crystal polymer with a controllable molecular structure according to claim 8, further comprising any one or more of the following conditions:
d1 The reaction temperature of the acetylation reaction is 120 to 150 ℃; the reaction time is 5 to 160s, so as to provide a third acetylated monomer;
d2 The reaction temperature of the prepolymerization reaction is 200 to 230 ℃; the reaction time is 20 to 260s, so as to provide a prepolymer with a polymerization degree of X' n;
d3 The third acetylation reaction mass comprises a third monomer feed selected from one or more of a hydroxyaromatic carboxylic acid, an aromatic diol, an aromatic diacid;
d4 The third acetylation reaction mass further comprises a third catalyst selected from an acetate salt of K, ca, mg, zn, or Co, or an ionic liquid; the dosage of the third catalyst is 0.001 to 1 percent of the total weight of the third acetylated monomer;
d5 The third acetylation reaction mass further comprises a third acetylating agent.
10. A system for continuously preparing a liquid crystal polymer with controllable molecular structure, which is used in the method according to any one of claims 1 to 9, and comprises:
a first multistage microchannel reaction device (1) and a first primary screw extrusion device (3) which are sequentially communicated in the material flow direction; a second multi-stage micro-channel reaction device (2) and a second one-stage screw extrusion device (4) which are sequentially communicated in the material flow direction;
a second-stage screw extrusion device (5), a third-stage screw extrusion device (6) and a fourth-stage screw extrusion device (7) which are communicated in sequence in the material flow direction;
the secondary screw extrusion device (5) is communicated with the first primary screw extrusion device (3) and the second primary screw extrusion device (4) respectively.
11. The system for continuously preparing a liquid crystal polymer with controllable molecular structure according to claim 10, further comprising any one or more of the following conditions:
e1 A vacuum pumping device is arranged on the three-stage screw extrusion device (6);
e2 The system further comprises a first raw material dissolving device (8), the first raw material dissolving device (8) is communicated with the first multistage microchannel reaction device (1);
e3 The system further comprises a second raw material dissolving device (10), the second raw material dissolving device (10) is communicated with the second multistage microchannel reaction device (2);
e4 The first multistage microchannel reaction device (1) and the second multistage microchannel reaction device (2) respectively comprise a plurality of microreactors connected in series;
e5 The system also comprises a cleaning device (12), wherein the cleaning device (12) is communicated with a pipeline between the first raw material dissolving device (8) and the first multi-stage microchannel reaction device (1); and the cleaning device (12) is communicated with a pipeline between the second raw material dissolving device (10) and the second multi-stage microchannel reaction device (2);
e6 The first primary screw extrusion device (3), the second primary screw extrusion device (4) and the secondary screw extrusion device (5) are respectively provided with a rectifying tower (13), a condenser (14) and a recovery device (15) which are communicated in sequence;
e7 The screw diameters of the first primary screw extrusion device (3) and/or the second primary screw extrusion device (4), the secondary screw extrusion device (5), the tertiary screw extrusion device (6) and the quaternary screw extrusion device (7) are gradually increased; the length-diameter ratio of the screw is gradually reduced; the rotating speed of the screw is gradually reduced;
e8 The first primary screw extrusion device (3), the second primary screw extrusion device (4), the second screw extrusion device (5), the third screw extrusion device (6) and the fourth screw extrusion device (7) are provided with heat-preservation jackets;
e9 The first primary screw extrusion device (3), the second primary screw extrusion device (4), the secondary screw extrusion device (5), the third screw extrusion device (6) and the fourth screw extrusion device (7) respectively comprise one or more screw extruders connected in series.
12. The system for continuously preparing liquid crystal polymer with controllable molecular structure according to claim 11, wherein a first pump body (9) is disposed on a communication pipeline between the first raw material dissolving device (8) and the first multi-stage microchannel reaction device (1).
13. The system for continuously preparing the liquid crystal polymer with the adjustable molecular structure according to claim 12, wherein the propelling speed of the first pump body (9) is 5 to 200ml/min.
14. The system for continuously preparing liquid crystal polymers with adjustable molecular structures according to claim 11, wherein a second pump body (11) is arranged on a communication pipeline between the second raw material dissolving device (10) and the second multi-stage microchannel reaction device (2).
15. The system for continuously preparing the liquid crystal polymer with the controllable molecular structure according to claim 14, wherein the propelling speed of the second pump body (11) is 5 to 200ml/min.
16. The system for continuously preparing the liquid crystal polymer with the controllable molecular structure according to claim 10 or 11, wherein the system further comprises a post-treatment device, the post-treatment device comprises a water cooling device (16), a granulating device (17), a drying device (18) and a finished product packaging device (19) which are sequentially communicated, and the discharge end of the four-stage screw extrusion device (7) is communicated with the water cooling device (16).
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