A liquid crystal polyester solution composition, a liquid crystal polyester film, its preparation method and application

Abstract

This invention discloses a liquid crystal polyester solution composition, a liquid crystal polyester film, its preparation method, and its applications, belonging to the field of polymer materials technology. The solution composition includes a liquid crystal polyester and an aprotic solvent, with the liquid crystal polyester comprising 5-20 wt% of the solution composition in solids. The liquid crystal polyester contains repeating units derived from 2-hydroxy-6-naphthoic acid, 2,5-furandicarboxylic acid, and p-aminophenol. The aprotic solvent is selected from N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, etc. This invention introduces 2,5-furandicarboxylic acid as a key monomer to construct a liquid crystal polyester with a ternary copolymer structure. This liquid crystal polyester dissolves in a low-corrosive aprotic solvent to form the solution composition. The resulting liquid crystal polyester film exhibits isotropic mechanical strength and is suitable for high-frequency electronic substrates such as those used in 5G communications, possessing significant market value and broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a liquid crystal polyester solution composition, a liquid crystal polyester film, its preparation method, and its application. Background Technology

[0002] Liquid crystal polyester (LCP) exhibits excellent flowability, low coefficient of thermal expansion, low dielectric constant, and low dielectric loss due to its highly ordered orientation structure in the molten state. It has become an ideal substrate for electronic components such as high-frequency communications (e.g., 5G / 6G), flexible circuit boards, and antenna substrates.

[0003] The main methods for preparing liquid crystal polyester films are melt blow molding and solution casting. Solution casting is considered an effective way to reduce the mechanical anisotropy of films because it can effectively weaken the directional alignment of molecular chains during solvent evaporation. Patent document CN101104705A discloses a technical solution for preparing LCP films using solution casting. The liquid crystal polyester used contains repeating units composed of aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, and monomers containing aromatic amines or aminophenols, specifically combinations such as 2-hydroxy-6-naphthoic acid, isophthalic acid, and p-aminophenol. Although this system can dissolve in aprotic solvents such as N-methylpyrrolidone, its monomer skeleton is still mainly composed of traditional benzene rings, naphthyl rings, or biphenyl structures, and it is still derived from traditional petroleum.

[0004] From the perspective of sustainable development and bio-based materials, developing novel LCPs that partially replace petroleum-based monomers has become a research hotspot. 2,5-Furandicarboxylic acid (FDCA) is a green platform compound that can be obtained from biomass resources. Its asymmetric furan ring structure can moderately disrupt the regularity of the molecular chain, potentially further improving the polymer's solubility in aprotic solvents. However, no reports have been published on a technical approach that directly incorporates FDCA into the LCP backbone for solution casting and systematically studies its impact on the anisotropy of film mechanical properties. Summary of the Invention

[0005] The primary objective of this invention is to provide a liquid crystal polyester solution composition by creatively introducing bio-based 2,5-furandicarboxylic acid as a key monomer to construct an LCP molecular system with a specific ternary copolymer structure, which is dissolved in a low-corrosive aprotic solvent to form a homogeneous solution composition.

[0006] A second objective of the present invention is to provide a liquid crystal polyester film, which is made from the above-mentioned liquid crystal polyester solution composition and has isotropic mechanical strength.

[0007] The third objective of this invention is to provide a method for preparing the liquid crystal polyester film. By casting the film using the liquid crystal polyester solution composition, the anisotropy of the mechanical properties in the longitudinal and transverse directions of the film is significantly reduced. This breakthrough overcomes the limitations of existing solution-based LCP films in terms of monomer selection and performance control, and has significant market value and broad application prospects.

[0008] A fourth objective of the present invention is to provide the application of the liquid crystal polyester film in the manufacture of electronic components, such as printed circuit boards.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a liquid crystal polyester solution composition comprising a liquid crystal polyester and an aprotic solvent, wherein the liquid crystal polyester has a solid content of 5 wt%-20 wt% in the liquid crystal polyester solution composition, and the liquid crystal polyester comprises repeating units derived from 2-hydroxy-6-naphthoic acid (HNA), 2,5-furandicarboxylic acid (FDCA), and p-aminophenol (AP); based on the total molar amount of monomers used to form the liquid crystal polyester being 100%, the molar percentage of the repeating units derived from 2-hydroxy-6-naphthoic acid is 30%-80%, the molar percentage of the repeating units derived from 2,5-furandicarboxylic acid is 10%-35%, the molar percentage of the repeating units derived from p-aminophenol is 10%-35%, and the sum of the molar percentages of the three is 100%.

[0011] Preferably, with the total molar amount of monomers used to form the liquid crystal polyester being 100%, the molar percentage of the repeating units derived from 2-hydroxy-6-naphthoic acid is 45%-70%, the molar percentage of the repeating units derived from 2,5-furandicarboxylic acid is 15%-30%, the molar percentage of the repeating units derived from p-aminophenol is 15%-30%, and the sum of the molar percentages of the three is 100%.

[0012] In the described liquid crystal polyester, the introduction of an asymmetric furan ring structure (from 2,5-furandicarboxylic acid) and p-aminophenol, which can form amide bonds, appropriately disrupts the regularity of the molecular chain, reducing crystallinity and melting temperature, thereby endowing the liquid crystal polyester with solubility in conventional aprotic polar solvents. Simultaneously, the specific ratio of the three monomers ensures that the material retains sufficient mesocrystalline units to maintain basic liquid crystallization, guaranteeing that the films prepared from it have good heat resistance.

[0013] Preferably, the liquid crystal polyester is prepared by melt polycondensation, specifically including the following steps:

[0014] (1) 2-hydroxy-6-naphthoic acid, 2,5-furandicarboxylic acid and p-aminophenol are mixed in proportion, and a catalyst and excess acylation agent are added. The acylation reaction is carried out at 130-180℃ for 5 minutes to 10 hours.

[0015] (2) After the acylation reaction is completed, the temperature is increased from 140℃ to 350℃ at a rate of 0.1-15℃ / min to carry out a melt polycondensation reaction. During the melt polycondensation reaction, the generated fatty acid byproducts and unreacted fatty acid anhydrides are removed by distillation, which pushes the reaction equilibrium towards the product direction to obtain liquid crystal resin.

[0016] (3) After the melt polycondensation reaction is completed, the liquid crystal resin is taken out, cooled and crushed, and then ground into powder or flakes. Solid-state polymerization reaction is carried out in an inert atmosphere at 250-350°C for 1-30 hours.

[0017] (4) After solid-state polymerization, the obtained aromatic liquid crystal polyester can be made into granules or molded using known methods.

[0018] More preferably, in step (1), the amidating agent is acetic anhydride, and its content is 1.05-1.2 times the phenolic hydroxyl equivalent, more preferably 1.05-1.1 times the phenolic hydroxyl equivalent. If the content of the added acylation agent is less than 1.0 times the phenolic hydroxyl equivalent, the acylated compound, aromatic hydroxycarboxylic acid, and aromatic dicarboxylic acid may sublimate during the subsequent melt polycondensation reaction, and the pipeline of the reaction vessel may be blocked; if the content of the added acylation agent is more than 1.2 times the phenolic hydroxyl equivalent, the final liquid crystal polyester will have a darker color.

[0019] More preferably, in step (1), the temperature of the acylation reaction is 140-160°C and the reaction time is 10 minutes to 3 hours.

[0020] More preferably, in step (2), after the acylation reaction is completed, the temperature is increased from 150°C to 330°C at a rate of 0.3-5°C / min to carry out melt polycondensation.

[0021] More preferably, in step (3), the solid-phase polymerization is carried out under stirring conditions or under static conditions, and the melt polymerization and solid-phase polymerization can be completed in the same reaction vessel.

[0022] More preferably, the acylation reaction and the melt polycondensation reaction are carried out in the presence of a catalyst, which is a metal salt catalyst or an organic catalyst. The metal salt catalyst is selected from at least one of magnesium acetate, tin acetate, tetrabutyl titanate, lead acetate, potassium acetate, antimony trioxide, and the like, and the organic catalyst is selected from at least one of N,N-dimethylaminopyridine, N-methylimidazole, and the like.

[0023] In some embodiments, these catalysts are typically added along with the monomers and do not require special removal after the acylation reaction, continuing to play a catalytic role in subsequent melt polycondensation. In some embodiments, the method for producing aromatic liquid crystal polyesters can employ batch processing equipment, continuous processing equipment, or other similar equipment. In some embodiments, fillers and additives may be added to the liquid crystal polyester. Fillers include: organic fillers, such as epoxy resin powder, melamine resin powder, urea resin powder, etc.; inorganic fillers, such as silicon, alumina, titanium dioxide, zirconium oxide, hydrated aluminum silicate, calcium carbonate, calcium phosphate; additives include known coupling agents, anti-precipitating agents, ultraviolet absorbers, and heat stabilizers. Furthermore, one or more thermoplastic resins, such as polyamide, polyphenylene sulfide, polyetheretherketone, polycarbonate, polyether, polyphenylene ether, polyetherimide, and elastomers, may also be added to the liquid crystal polyester.

[0024] Preferably, the liquid crystal polyester solution composition includes the aforementioned liquid crystal polyester and an aprotic solvent. There is no particular limitation on the amount of the aprotic solvent used, as long as it can dissolve the liquid crystal polyester, and it can be selected appropriately according to actual needs.

[0025] The aprotic solvent is selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and γ-butyrolactone (GBL), preferably N-methylpyrrolidone.

[0026] Preferably, the liquid crystal polyester solution composition has a viscosity of 100-5000 mPa·s at 25°C, exhibits extremely low corrosivity to conventional metals such as copper and stainless steel, and is easy to store and transport.

[0027] In a second aspect, the present invention provides a liquid crystal polyester film, which is prepared from the liquid crystal polyester solution composition.

[0028] Preferably, the ratio of the longitudinal to transverse tensile strength of the liquid crystal polyester film is less than 1.15, more preferably between 1.05 and 1.15, which significantly reduces mechanical anisotropy and approaches isotropy.

[0029] Preferably, the thickness of the liquid crystal polyester film is 5-200 μm, more preferably 25-100 μm.

[0030] A third aspect of the present invention provides a method for preparing a liquid crystal polyester film, comprising the following steps:

[0031] (a) Dissolving liquid crystal polyester in an aprotic solvent to form a homogeneous liquid crystal polyester solution composition;

[0032] (b) The liquid crystal polyester solution composition is coated onto a support to form a wet film;

[0033] (c) After the wet film is removed from the nonprotic solvent, it is peeled off from the support to obtain a liquid crystal polyester film.

[0034] Preferably, in step (b), the coating is performed using at least one of blade coating, roller coating, and slot extrusion coating.

[0035] Preferably, in step (b), the support is selected from at least one of glass plate, stainless steel strip or polyester release film.

[0036] Preferably, in step (c), the wet film is dried at 80-200°C for 10 minutes to 2 hours, and then heat-treated at 200-300°C for 30 minutes to 5 hours to remove the aprotic solvent.

[0037] In some embodiments, the method for removing aprotic solvents is not particularly limited, and the aprotic solvents can be removed by at least one of heating evaporation, depressurization, or ventilation, with evaporation being preferred. From the perspective of yield and ease of operation, heating evaporation under ventilation conditions is more preferred, for example, drying at 80-200°C for 10 minutes to 2 hours, followed by heat treatment at 200-300°C for 30 minutes to 5 hours, with the specific time adjusted according to the type of solvent and the film thickness.

[0038] A fourth aspect of the invention provides the application of the liquid crystal polyester film in the fabrication of electronic components, such as printed circuit boards.

[0039] Compared with the prior art, the present invention provides a novel liquid crystal polyester solution composition with bio-based 2,5-furandicarboxylic acid as the key monomer and a method for preparing a cast film. The film has isotropic mechanical strength, and its beneficial effects include at least the following:

[0040] 1. This invention creatively introduces 2,5-furandicarboxylic acid as a key monomer to construct a novel LCP molecular system. It can not only dissolve well in low-corrosive aprotic solvents, but also the film obtained has significantly reduced anisotropy in mechanical properties in both the longitudinal and transverse directions, exhibiting significant mechanical isotropy. This overcomes the limitations of existing solution-based LCP films in terms of monomer selection and performance control.

[0041] 2. The liquid crystal polyester solution composition of the present invention has the advantages of low corrosivity and easy processing. The film made using this solution composition has small mechanical anisotropy between the longitudinal direction (coating direction) and the transverse direction (perpendicular to the coating direction) and has excellent mechanical strength.

[0042] 3. The liquid crystal polyester film of the present invention exhibits good dielectric properties at high frequencies, and the liquid crystal polyester itself has low water absorption, making it very suitable for use as a film for electronic components, such as printed circuit boards, in the field of high-frequency electronic substrates for 5G communication and other applications.

[0043] 4. The liquid crystal polyester film preparation process of the present invention is simple, requiring no complex biaxial stretching equipment. High-performance LCP films can be produced using conventional solution coating and drying equipment, making it easy to industrialize and possessing significant market value and broad application prospects. Detailed Implementation

[0044] To more fully understand and demonstrate the technical solutions, objectives, and advantages of the present invention, the technical effects produced by the present invention will be further described in detail and completely below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be noted that other embodiments obtained by those skilled in the art without departing from the concept of the present invention are all within the protection scope of the present invention.

[0045] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0046] Synthesis example 1

[0047] In a reactor equipped with a stirrer, nitrogen inlet, condenser, and thermometer, 940.90 g (5 mol) of 2-hydroxy-6-naphtholic acid (HNA), 390.23 g (2.5 mol) of 2,5-furandicarboxylic acid (FDCA), 272.82 g (2.5 mol) of p-aminophenol (AP), and 1122.99 g (11 mol, 10% excess) of acetic anhydride were added. The acylation reaction was carried out at 140 °C for 1.5 hours under nitrogen protection. Subsequently, the temperature was gradually increased to 320 °C over 170 minutes, and a vacuum was applied. The reaction was stopped when the viscosity of the reactants significantly increased and the target torque was reached. The product was discharged under nitrogen protection, and after cooling, a pale yellow solid liquid crystal polyester was obtained, labeled LCP-1.

[0048] Synthesis example 2

[0049] The synthesis was basically the same as in Example 1, except that the molar ratio of the monomers was adjusted to: HNA 1129.08g (6 mol), FDCA 312.18g (2 mol), AP 220.22g (2 mol), and acetic anhydride 1122.99g (11 mol, 10% excess), to obtain liquid crystal polyester LCP-2.

[0050] Synthesis example 3

[0051] The synthesis was basically the same as in Example 1, except that the molar ratio of the monomers was adjusted to: HNA 1317.26 g (7 mol), FDCA 234.14 g (1.5 mol), AP 165.17 g (1.5 mol), and acetic anhydride 1122.99 g (11 mol, 10% excess), to obtain liquid crystal polyester LCP-3.

[0052] Synthesis example 4

[0053] The process was essentially the same as in Synthesis Example 1, except that the material temperature was raised to 320°C over 170 minutes without vacuum, and maintained at this constant temperature to remove distilled acetic acid and unreacted acetic anhydride byproducts. The reaction was terminated when the torque meter rose, and the product was removed. The resulting solid component was then cooled to room temperature, crushed using a coarse roller, and left in a nitrogen atmosphere at 250°C for 3 hours to allow for solid-state polymerization. When the final resin was observed using a polarizing microscope, it exhibited the characteristic schlieren pattern of a liquid crystal phase at 200°C.

[0054] Synthesis example 5

[0055] The monomer molar ratio was adjusted to: HNA (8.5 mol), FDCA (0.75 mol), AP (0.75 mol). Polymerization was attempted using the same method as in Synthesis Example 1. During the reaction, the viscosity of the system increased too quickly, making discharge difficult, and brittle solid LCP-5 was obtained.

[0056] Synthesis example 6

[0057] In a reactor equipped with a stirrer, nitrogen inlet, condenser, and thermometer, 940.90 g (5 mol) of HNA, 465.53 g (2.5 mol) of 4,4-dihydroxybiphenyl, 415.33 g (2.5 mol) of isophthalic acid, and 1122.99 g (11 mol) of acetic anhydride were added. After the air in the reactor was completely replaced by nitrogen, the acylation reaction was carried out at 140 °C for 1.5 hours under nitrogen inflow and nitrogen protection.

[0058] Subsequently, the temperature was gradually increased to 320°C over 170 minutes, and a vacuum was drawn. Once the viscosity of the reactants increased significantly and the target torque was reached, the reaction was stopped, and the material was discharged under nitrogen protection. After cooling, a pale yellow solid liquid crystal polyester was obtained, labeled as LCP-6.

[0059] Example 1: Preparation of liquid crystal polyester film (solution casting method)

[0060] 0.5 g of LCP-1 polyester was added to 9.5 g of N-methylpyrrolidone (NMP) and heated to 120 °C. The powder was confirmed to be completely dissolved to form a transparent solution. The solution was stirred and air bubbles removed to obtain a liquid crystal polyester solution. This solution was then coated onto a copper foil using a rod coating method, and the solvent was removed by heating at 100 °C for 1 hour. Following this, a heat treatment was performed at 250 °C for 1 hour to obtain a 15 μm thick film coated with copper foil, denoted as F-1.

[0061] Examples 2-4

[0062] Using the same method as in Example 1, thin films F-2 to F-4 were prepared using liquid crystal polyester LCP-2 / 3 / 4, respectively, with the specific parameters as follows:

[0063] Thin film F-2: LCP-2 is used, NMP is used as solvent, and the film thickness is 25μm.

[0064] Thin film F-3: LCP-3 is used, NMP is used as solvent, and the film thickness is 65μm.

[0065] Thin film F-4: LCP-4 was used, NMP was used as the solvent, and the film thickness was 105 μm.

[0066] Comparative Example 1

[0067] Using the same method as in Example 1, 0.5 g of LCP-5 was added to 9.5 g of NMP and heated to 120°C. It was found that the powder could not be completely dissolved.

[0068] Comparative Example 2

[0069] Using the same method as in Example 1, 0.5 g of LCP-6 was added to 9.5 g of NMP and heated to 120°C. The results showed that the powder only swelled and could not be used to prepare a uniform solution composition or film.

[0070] Comparative Example 3: LCP films prepared by melt extrusion

[0071] A commercially available melt-type fully aromatic liquid crystal polyester (mainly composed of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, molar ratio 73:27) was selected, plasticized using a single-screw extruder, and extruded into a film via blow molding. The die temperature was 290℃, the die diameter was 30mm, the die lip clearance was 0.7mm, the blow-up ratio was 6.2, and the resulting liquid crystal polyester film had a melting point of 281℃ and a thickness of 50µm, denoted as CF-1.

[0072] Thin film performance testing

[0073] The following performance tests were performed on films F-1 to F-4 and CF-1 of Comparative Example 3:

[0074] Tensile strength test: According to ASTM D882 standard, a universal testing machine was used to sample and test the longitudinal (MD) and transverse (TD) sections of the film at 23℃ and 50% relative humidity, and the tensile strength and MD / TD ratio were calculated.

[0075] Thermal performance testing: Thermogravimetric analysis (TGA, nitrogen atmosphere, heating rate 10℃ / min) was used to test the 5% thermogravimetric temperature (Td, 5%).

[0076] The test results are shown in Table 1:

[0077] Table 1

[0078]

[0079] The test results show that:

[0080] (1) Mechanical anisotropy: The ratio of longitudinal to transverse tensile strength (MD / TD) of the films F-1 to F-4 prepared by the present invention is all less than 1.15, with the lowest reaching 1.08, showing mechanical properties close to isotropic; while the melt extrusion film CF-1 of Comparative Example 3 has an MD / TD ratio as high as 2.5, showing significant anisotropy.

[0081] (2) Heat resistance: Although the present invention introduces a flexible furan ring and amide structure to reduce crystallinity, the Td of the film and the 5% thermal weight loss temperature are still higher than 450℃, indicating that the material has good thermal stability.

[0082] (3) Solubility: In Comparative Example 1, the rigid HNA in the monomer ratio was too high (85%), while the solubility-improving monomers FDCA and AP were too low, resulting in excessively high polymer crystallinity, which could not be dissolved in NMP. This proves that the specific ratio range of the present invention is the key to achieving solubility. In Comparative Example 2, the resin could not be completely dissolved because 4,4-dihydroxydiphenyl and isophthalic acid monomers were used to replace FDCA and AP in Examples 1-4. This proves that the selection of monomers for FDCA and AP is also a key factor in achieving solubility.

[0083] In summary, this invention utilizes bio-based 2,5-furandicarboxylic acid as a key monomer to prepare novel liquid crystal polyester solution compositions. The liquid crystal polyester film prepared by the casting method exhibits isotropic mechanical strength with significantly reduced anisotropy in mechanical properties along the longitudinal and transverse directions, overcoming the limitations of existing solution-based LCP films in terms of monomer selection and performance control. Furthermore, this liquid crystal polyester film demonstrates excellent dielectric properties at high frequencies, making it highly suitable for use as a film in electronic components, such as printed circuit boards, and possessing significant market value and broad application prospects.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A liquid crystal polyester solution composition, characterized in that, It includes a liquid crystal polyester and an aprotic solvent, wherein the solid content of the liquid crystal polyester in the liquid crystal polyester solution composition is 5wt%-20wt%; the liquid crystal polyester comprises repeating units derived from 2-hydroxy-6-naphthoic acid, 2,5-furandicarboxylic acid and p-aminophenol, wherein, based on the total molar amount of monomers used to form the liquid crystal polyester being 100%, the molar percentage of the repeating units derived from 2-hydroxy-6-naphthoic acid is 30%-80%, the molar percentage of the repeating units derived from 2,5-furandicarboxylic acid is 10%-35%, the molar percentage of the repeating units derived from p-aminophenol is 10%-35%, and the sum of the molar percentages of the three is 100%.

2. The liquid crystal polyester solution composition according to claim 1, characterized in that, With the total molar amount of monomers used to form the liquid crystal polyester being 100%, the molar percentage of the repeating units derived from 2-hydroxy-6-naphthoic acid is 45%-70%, the molar percentage of the repeating units derived from 2,5-furandicarboxylic acid is 15%-30%, the molar percentage of the repeating units derived from p-aminophenol is 15%-30%, and the sum of the molar percentages of the three is 100%; and / or the aprotic solvent is selected from at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and γ-butyrolactone.

3. The liquid crystal polyester solution composition according to claim 1, characterized in that, The liquid crystal polyester is prepared by melt polycondensation, including the following steps: (1) 2-hydroxy-6-naphthoic acid, 2,5-furandicarboxylic acid and p-aminophenol are mixed in proportion, and an excess of acylation agent is added. The acylation reaction is carried out at 130-180℃ for 5 minutes to 10 hours. (2) After the acylation reaction is completed, the temperature is increased from 140℃ to 350℃ at a rate of 0.1-15℃ / min to carry out a melt polycondensation reaction to obtain a liquid crystal resin; (3) After the melt polycondensation reaction is completed, the liquid crystal resin is taken out, cooled and crushed, and then ground into powder or flakes. Solid-state polymerization reaction is carried out at 250-350°C for 1-30 hours in an inert atmosphere to obtain aromatic liquid crystal polyester. (4) After the solid-state polymerization reaction is completed, the aromatic liquid crystal polyester obtained is made into particles or subjected to molding process.

4. The liquid crystal polyester solution composition according to claim 3, characterized in that, In step (1), the amidating agent is acetic anhydride, the content of which is 1.05-1.2 times the phenolic hydroxyl equivalent; and / or the temperature of the acylation reaction is 140-160℃, and the reaction time is 10 minutes to 3 hours; In step (2), after the acylation reaction is completed, the temperature is increased from 150°C to 330°C at a rate of 0.3-5°C / min for melt polycondensation. During the melt polycondensation reaction, the generated fatty acid byproducts and unreacted fatty acid anhydrides are removed by distillation, which pushes the reaction equilibrium toward the product.

5. The liquid crystal polyester solution composition according to claim 3, characterized in that, The acylation reaction and melt polycondensation reaction are carried out in the presence of a catalyst, which is a metal salt catalyst or an organic catalyst. The metal salt catalyst is selected from at least one of magnesium acetate, tin acetate, tetrabutyl titanate, lead acetate, potassium acetate, antimony trioxide, and the like. The organic catalyst is selected from at least one of N,N-dimethylaminopyridine, N-methylimidazole, and the like.

6. The liquid crystal polyester solution composition according to claim 3, characterized in that, In step (4), at least one of thermoplastic resin, filler, and additive is added to the aromatic liquid crystal polyester to form granules or to perform molding processing; wherein, the thermoplastic resin is selected from at least one of polyamide, polyphenylene sulfide, polyether ether ketone, polycarbonate, polyether, polyphenylene ether, polyetherimide, and elastomer; the filler is selected from at least one of epoxy resin powder, melamine resin powder, urea resin powder, silicon, alumina, titanium dioxide, zirconium oxide, hydrated aluminum silicate, calcium carbonate, and calcium phosphate; and the additive is selected from at least one of coupling agent, anti-precipitant, ultraviolet absorber, and heat stabilizer.

7. The liquid crystal polyester solution composition according to claim 1, characterized in that, The viscosity of the liquid crystal polyester solution composition at 25°C is 100-5000 mPa·s.

8. A liquid crystal polyester film, characterized in that, It is prepared from the liquid crystal polyester solution composition according to any one of claims 1 to 7.

9. The liquid crystal polyester film according to claim 8, characterized in that, The ratio of the longitudinal to transverse tensile strength of the liquid crystal polyester film is less than 1.

15.

10. The liquid crystal polyester film according to claim 8, characterized in that, The thickness of the liquid crystal polyester film is 5-200 μm.

11. The method for preparing the liquid crystal polyester film according to any one of claims 8 to 10, characterized in that, Includes the following steps: (a) Dissolving liquid crystal polyester in an aprotic solvent to form a homogeneous liquid crystal polyester solution composition; (b) The liquid crystal polyester solution composition is coated onto a support to form a wet film; (c) After the wet film is removed from the nonprotic solvent, it is peeled off from the support to obtain a liquid crystal polyester film.

12. The method for preparing the liquid crystal polyester film according to claim 11, characterized in that, In step (b), the coating is performed using at least one of blade coating, roller coating, and slot extrusion coating; and / or the support is selected from at least one of glass plate, stainless steel strip, or polyester release film. And / or in step (c), the wet film is dried at 80-200°C for 10 minutes to 2 hours, and then heat-treated at 200-300°C for 30 minutes to 5 hours to remove the aprotic solvent.

13. The use of the liquid crystal polyester film of any one of claims 8 to 10 in the manufacture of electronic components.

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