Liquid crystal polymer, polymerization method thereof and liquid crystal polymer composition

Abstract

The invention discloses a liquid crystal polymer, which is derived from the following repetitive units in molar percentage: 45-75 mol% of-O-Ar1-CO-unit; a-CO-Ar < 2-> CO <-> unit is 12.5 to 27.5 mol%; 12.5 to 27.5 mol% of an-O-Ar3 <->-O <-> unit; the-O-Ar < 1-CO-> unit is derived from at least one of 4-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid; the-CO-Ar2-CO-unit is derived from terephthalic acid; the-O-Ar3-O-unit is derived from at least one of hydroquinone and 4, 4 '-dihydroxybiphenyl. According to the liquid crystal polymer disclosed by the invention, the content of a terminal phenol group byproduct in the liquid crystal polymer with a specific repetitive unit is controlled to be less than or equal to 0.5% of the total weight of the liquid crystal polymer, so that the thermogravimetric loss rate of the liquid crystal polymer is less than or equal to 2.0%, and the liquid crystal polymer has good anti-foaming performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a liquid crystal polymer and a polymerization method thereof and a liquid crystal polymer composition. Background Art

[0002] Thermotropic aromatic liquid crystal polyester (TLCP) has received widespread attention in the research and industrial fields. It is widely used in the connector field due to its excellent mechanical properties, processing properties, thermal stability, chemical corrosion resistance, electrical insulation, and self-flame retardancy.

[0003] With the miniaturization, lightness, and personalization of smart terminal devices, LCP materials are preferred as thin-wall plug-in molding materials due to their excellent melt fluidity, heat resistance, and mechanical strength. However, LCP also has a typical performance disadvantage, which is that blistering is prone to occur on the surface during lead-free soldering (usually the soldering temperature is 260°C), causing soldering failure and a high defect rate.

[0004] Patent CN102140248A application discloses a liquid crystal resin combination: a fibrous inorganic filler (glass fiber is used in the patent implementation) and an equal amount of glass beads are added to the liquid crystal resin to improve the foaming resistance. The patent implementation uses a mixture of 30wt% to 40wt% of glass beads and glass fibers to fill the liquid crystal resin to obtain a composition with good foaming resistance. Patent CN102796351B application discloses a method of adding an anti-foaming agent from a liquid crystal composition by adding 0.1% to 15%, thereby reducing the foaming performance of a liquid crystal polymer composition. However, the above inventions all improve the foaming resistance from the aspect of adding auxiliary agents, and do not fundamentally solve the anti-foaming problem from the aspect of liquid crystal polyester. Summary of the invention

[0005] The object of the present invention is to provide a liquid crystal polymer with good anti-foaming performance and a polymerization method thereof.

[0006] The present invention is achieved through the following technical solutions: A liquid crystal polymer, based on mole percent, derived from the following repeating units: -O-Ar1-CO-unit 45-75 mol%; -CO-Ar2-CO- units 12.5-27.5 mol%; -O-Ar3-O-unit 12.5-27.5mol%; -O-Ar1-CO- unit is derived from at least one of 4-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid; The -CO-Ar2-CO- unit is derived from terephthalic acid; The -O-Ar3-O- unit is derived from at least one of hydroquinone and 4,4'-dihydroxybiphenyl; Based on the total weight of the liquid crystal polymer, the phenol end group content is ≤0.5%.

[0007] Preferably, the content of -O-Ar1-CO- units is 45-65 mol%; the content of -CO-Ar2-CO- units is 17.5-27.5 mol%; the content of -O-Ar3-O- units is 17.5-27.5 mol%, based on the total weight of the liquid crystal polymer, and the content of phenol end groups is ≤0.4%.

[0008] More preferably, the content of -O-Ar1-CO- units is 45-63 mol%; the content of -CO-Ar2-CO- units is 18.5-27.5 mol%; the content of -O-Ar3-O- units is 18.5-27.5 mol%, and the content of phenol end groups is ≤0.35% based on the total weight of the liquid crystal polymer.

[0009] In the liquid crystal polymer, the molar percentage of the -O-Ar1-CO- unit, the -CO-Ar2-CO- unit and the -O-Ar3-O- unit is 100% in total.

[0010] The thermogravimetric loss rate of the liquid crystal polymer of the present invention is ≤2.0%, preferably ≤1.8%, and more preferably ≤1.7%.

[0011] The test method for the phenol end group content is as follows: take 500 mg of liquid crystal polymer sample and put it into a 25 ml volumetric flask, add 2.5 ml of 5 mol / L NaOH / CH 3 OH mixed solution, and add 10ml of dehydrated dimethyl sulfoxide. Maintain a nitrogen atmosphere at a temperature of 60°C, shake the volumetric flask for more than 24 hours, and after the sample is completely hydrolyzed, add water to dissolve the aromatic monomer salt formed by hydrolysis, and neutralize the excess alkali with hydrochloric acid, freeze-dry the obtained sample to obtain the product of complete hydrolysis of liquid crystal polyester. The hydrolyzed sample was measured using a Bruker advance III 400 MHz nuclear magnetic resonance spectrometer from Bruker, USA. Tetramethylsilane (TMS) was used as an internal standard, and deuterated dimethyl sulfoxide (DMSO-d6) was used as a solvent. The ratio of the phenol peak area to the integrated area of ​​the monomer attribute peak obtained by hydrolyzing the liquid crystal polyester to the phenol attribute peak area was calculated as the phenol end group content.

[0012] The test method of thermal weight loss rate is: using (thermal gravimetric analyzer) TGA to measure, the test atmosphere is nitrogen, the sample is heated to 150℃ at 20℃ / min, and kept at 150℃ for 10min, then heated to 400℃ at 20℃ / min, and kept at 400℃ for 30min, the timing starts when the test temperature reaches 400℃, the weight G0 is recorded at 0min, and the weight G30 is recorded at 30min. Thermal weight loss rate = (G0-G30) / G0*100%.

[0013] Preferably, the -O-Ar1-CO- unit is derived from 4-hydroxybenzoic acid, and the -O-Ar3-O- unit is derived from 4,4'-dihydroxybiphenyl.

[0014] The melt viscosity of the liquid crystal polyester is in the range of 10-200 Pa.s. The test was conducted using a Dynisco LCR7000 capillary rheometer at a temperature of 20°C above the melting point and a shear rate of 1000S. -1 , using a die with an inner diameter of 1mm and a length of 40mm, and preheating for 4 minutes to obtain the data.

[0015] The melting point range of the liquid crystal polyester is 360-460°C. The melting point is measured by DSC 200 F3 of NETZSCH Company. The temperature is increased from room temperature to the maximum temperature of the melting point + (20~80)°C at a heating rate of 20°C / min, and then the temperature is cooled to room temperature at a rate of 20°C / min after staying at this temperature for 2 minutes. After the test sample is kept at room temperature for 2 minutes, it is heated again at a heating rate of 20°C / min to the maximum temperature of the melting point + (20~80)°C to obtain the second melting curve of the polymer, and the melting peak value is selected as the melting point.

[0016] The polymerization method of the liquid crystal polymer of the present invention comprises the following steps: acylation stage, polycondensation stage, reduced pressure polycondensation stage, and solid phase viscosity enhancement stage. Those skilled in the art can routinely select the polymerization method and process parameters of the liquid crystal polymer to achieve control of the phenol end group content.

[0017] In one embodiment, the method for polymerizing a liquid crystal polymer comprises the following steps: (1) Acylation stage: The monomers corresponding to the -O-Ar1-CO- unit and the -O-Ar3-O- unit, the acylating agent and the catalyst are simultaneously added into the reactor for acylation reaction at a temperature of 130-160°C for 1.5-5h; (2) Polycondensation stage: melt polycondense the acylated reactant in step (1) with the monomer corresponding to the -CO-Ar2-CO- unit, heat the temperature to 280°C at a heating rate of 0.3-1.5°C / min, control the heating rate so that the heating time in the 280-300°C heating stage is maintained at 1-3h, and finally continue to heat the temperature at a heating rate of 0.3-1.5°C / min to 10-30°C above the melting point, and continuously distill out by-products during the heating period; (3) Reduced pressure polymerization section: Reduced pressure polymerization is carried out, the target vacuum degree is 0.1 kPa ~ 40 kPa, the reduced pressure polymerization time is controlled at 3.5-6 hours, and the temperature of the prepolymer melt is finally controlled to be 10 ~ 30 ° C above the melting point when discharged; (4) Solid-phase thickening process: After reaching the target melt viscosity through a one-step melt polymerization method, the melt is discharged in a molten state, and then cut or crushed after cooling to obtain a liquid crystal polymer.

[0018] In one embodiment, the terminal phenol groups of the liquid crystal polymer can be capped with a capping agent to achieve control of the content of the phenol terminal groups. The capping agent includes but is not limited to benzoic acid.

[0019] In one embodiment, the polymerization method using the end-capping agent comprises the following steps: (1) Acylation stage: The monomers corresponding to the -O-Ar1-CO- unit and the -O-Ar3-O- unit, the acylating agent and the catalyst are simultaneously added into the reactor for acylation reaction at a temperature of 130-160°C for 1.5-5h; (2) Polycondensation stage: melt polycondense the acylated reactant in step (1) with the monomer corresponding to the -CO-Ar2-CO- unit, heat the temperature to 280°C at a heating rate of 0.3-1.5°C / min, control the heating rate so that the heating time in the 280-300°C heating stage is maintained at 1-3h, and finally continue to heat the temperature at a heating rate of 0.3-1.5°C / min to 10-30°C above the melting point, and continuously distill out by-products during the heating period; (3) Reduced pressure polymerization section: Add the end-capping agent and carry out reduced pressure polymerization. The target vacuum degree is 0.1 kPa to 40 kPa. The reduced pressure polymerization time is controlled at 0.5 to 3 hours. Finally, the temperature of the prepolymer melt is controlled to be 10 to 30 °C above the melting point when discharged. (4) Solid-phase thickening process: After reaching the target melt viscosity through a one-step melt polymerization method, the melt is discharged in a molten state, and then cut or crushed after cooling to obtain a liquid crystal polymer.

[0020] The acylating agent is selected from at least one of acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, 2-ethylhexanoic anhydride, dichloroacetic anhydride, dibromoacetic anhydride, difluoroacetic anhydride, maleic anhydride, and succinic anhydride; the molar ratio of the acylating agent to the total molar amount of phenolic hydroxyl groups in the monomer is (1-1.2):1; the catalyst is selected from at least one of magnesium acetate, sodium acetate, stannous acetate, tetrabutyl titanate, lead acetate, potassium acetate, and antimony trioxide; and the added amount of the catalyst is 20-2000ppm of the theoretical output amount.

[0021] The present invention also discloses a liquid crystal polymer composition, which comprises the following components in parts by weight: 45-78 parts of the above-mentioned liquid crystal polymer; 22-55 parts of reinforcement material; The reinforcing material is selected from at least one of fibrous reinforcing fillers and granular reinforcing fillers.

[0022] The fibrous reinforcing filler is selected from at least one of glass fiber, potassium titanate fiber, ceramic fiber, wollastonite fiber, metal carbide fiber, metal solidified fiber, asbestos fiber, alumina fiber, silicon carbide fiber, gypsum fiber, boron fiber, potassium titanate whisker, and aluminum borate whisker.

[0023] The granular reinforcing filler is selected from at least one of talc, carbon black, gypsum, asbestos, zeolite, kaolin, montmorillonite, clay, hectorite, aluminosilicate, silicon dioxide, titanium oxide, aluminum oxide, zinc oxide, zirconium oxide, iron oxide, magnesium titanate, dolomite, aluminum sulfate, barium sulfate, magnesium sulfate, calcium carbonate, mica, quartz powder, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, glass beads, ceramic beads, boron nitride, and silicon carbide.

[0024] The reinforcing material is selected from at least one of a fibrous reinforcing filler and a granular reinforcing filler, wherein the aspect ratio of the fibrous filler is 600:1-100:1, and the average particle size of the granular reinforcing filler is less than 100 microns.

[0025] The testing method for the aspect ratio of the fibrous filler is: place the sample under a two-dimensional imaging instrument, measure the length and diameter of the fibrous filler after magnification, and calculate the ratio as the aspect ratio.

[0026] The average particle size of the granular reinforcing filler is measured by a laser particle size analyzer.

[0027] The present invention has the following beneficial effects: The present invention finds that by controlling the content of phenol terminal byproducts in a liquid crystal polymer of a specific repeating unit to ≤0.5% of the total weight of the liquid crystal polymer, the thermogravimetric loss rate of the liquid crystal polymer can be improved and the anti-foaming performance of the liquid crystal polymer can be enhanced. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0029] The sources of raw materials used in the present invention are as follows: 4-Hydroxybenzoic acid: Sigma-Aldrich, purity>99%; 2-Hydroxy-6-naphthoic acid: Sigma-Aldrich, purity > 99%; Terephthalic acid: Sigma-Aldrich, purity > 99%; 4,4'-Dihydroxybiphenyl: Sigma-Aldrich, purity >99%; Hydroquinone: Sigma-Aldrich, purity>99%; Isophthalic acid: Sigma-Aldrich, purity > 99%; Fiberglass: Owens Corning; Talc: Qingdao Kaiwell Powder Engineering Technology Co., Ltd.

[0030] The polymerization method of the liquid crystal polymer of Examples A1-A10 and Comparative Examples B1-B5 is as follows: Acylation step: monomers corresponding to -O-Ar1-CO- units and -O-Ar3-O- units, acylating agent (acetic anhydride), and catalyst (magnesium acetate) are simultaneously introduced into a reactor, and an acylation reaction is carried out at a temperature of 130-160° C. for 1.5-5 h; Polycondensation step: the reactant acylated in step (1) is subjected to melt polycondensation with the monomer corresponding to the -CO-Ar2-CO- unit, and the temperature is raised to 280° C. at a heating rate of 0.3-1.5° C. / min, and the heating rate is controlled so that the temperature is kept at 280° C. The heating time of the -300℃ heating section is maintained at 1-3h, and finally the temperature is continued to be raised to 10-30℃ above the melting point at a heating rate of 0.3-1.5℃ / min, and by-products are continuously distilled during the heating period; reduced pressure polymerization section: reduced pressure polymerization is carried out, the target vacuum degree is 12kPa~15kPa, and the reduced pressure polymerization time is (see table), and the temperature of the prepolymer melt is finally controlled to be 10-30℃ above the melting point during discharge; solid phase viscosity increasing section: after reaching the target melt viscosity through a one-step melt polymerization method, the melt is discharged in a molten state, and cut or crushed after cooling to obtain a liquid crystal polymer.

[0031] Example A11-12: Polymerization method of liquid crystal polymer: the acylation section, polycondensation section and solid phase viscosity increasing section are the same as the above method, the difference is in the reduced pressure polymerization section: benzoic acid is added as a capping agent (the added amount is 0.5% of the molar amount of -O-Ar3-O- unit), and reduced pressure polymerization is carried out. The target vacuum degree is 12kPa~15kPa, the reduced pressure polymerization time is 0.5 hour, and the temperature of the prepolymer melt is finally controlled to be 10~30°C above the melting point during discharge.

[0032] Various test methods: (1) Melt viscosity was measured by the following method: using a Dynisco LCR7000 capillary rheometer at a temperature of 20°C above the melting temperature and a shear rate of 1000 s. -1 , using a die with an inner diameter of 1mm and a length of 40mm, and preheating for 4 minutes to obtain the data.

[0033] (2) Phenol end group content: Take 500 mg of liquid crystal polymer sample and put it into a 25 ml volumetric flask. Add 2.5 ml of 5 mol / L NaOH / CH 3 OH mixed solution, and add 10ml of dehydrated dimethyl sulfoxide. Maintain a nitrogen atmosphere at a temperature of 60°C, shake the volumetric flask for more than 24 hours, and after the sample is completely hydrolyzed, add water to dissolve the aromatic monomer salt formed by hydrolysis, and neutralize the excess alkali with hydrochloric acid, freeze-dry the obtained sample to obtain the product of complete hydrolysis of liquid crystal polyester. The hydrolyzed sample was measured using a Bruker advance III 400 MHz nuclear magnetic resonance spectrometer from Bruker, USA. Tetramethylsilane (TMS) was used as an internal standard, and deuterated dimethyl sulfoxide (DMSO-d6) was used as a solvent. The ratio of the phenol peak area to the integrated area of ​​the monomer attribute peak obtained by hydrolyzing the liquid crystal polyester to the phenol attribute peak area was calculated as the phenol end group content.

[0034] (3) Thermal weight loss rate: Determined by TGA (thermal weight loss analyzer), with nitrogen as the test atmosphere, the sample is heated to 150°C at 20°C / min, and kept at 150°C for 10 min, then heated to 400°C at 20°C / min, and kept at 400°C for 30 min. When the test temperature reaches 400°C, start timing, record the weight G0 at 0 min, and record the weight G30 at 30 min. Thermal weight loss rate = (G0-G30) / G0*100%.

[0035] (4) Anti-foaming property: 100 shrinkage plates with a length, width and thickness of 100×100×1.0 mm were molded by injection molding and heated in a high-temperature oven at 260°C for 5 min. The number of blistering plates was divided by the total number.

[0036] Table 1: Liquid crystal polymer repeating unit mol% content and test results A-1 A-2 A-3 A-4 A-5 4-Hydroxybenzoic acid 45 48 60 63 65 2-Hydroxy-6-naphthoic acid Terephthalic acid 27.5 26 20 18.5 17.5 Isophthalic acid 4,4'-Dihydroxybiphenyl 27.5 26 20 18.5 17.5 Hydroquinone Compression polymerization time, h 5.8 5.2 4.7 4.4 4.1 Melt viscosity, Pa.s 40.2 38.5 42.6 43.1 41.8 Phenol end group content, % 0.21 0.26 0.30 0.33 0.36 Thermal weight loss rate, % 1.13 1.23 1.35 1.41 1.77 Foaming ratio% 0 0 0 0 0 Table 1 continued: A-6 A-7 A-8 A-9 A-10 4-Hydroxybenzoic acid 75 45 25 2-Hydroxy-6-naphthoic acid 45 45 20 Terephthalic acid 12.5 27.5 27.5 27.5 27.5 Isophthalic acid 4,4'-Dihydroxybiphenyl 12.5 27.5 27.5 Hydroquinone 27.5 27.5 Compression polymerization time, h 3.7 4.5 4.5 4.5 5.5 Melt viscosity, Pa.s 40.3 40.5 41.6 42.0 40.7 Phenol end group content, % 0.46 0.31 0.33 0.34 0.25 Thermal weight loss rate, % 1.96 1.52 1.62 1.56 1.52 Foaming ratio% 0 0 0 0 0 It can be seen from the liquid crystal polymer A1-10 that when the repeating unit and the phenol end group of the liquid crystal polymer are controlled within the scope of the present invention, the thermal weight loss rate of the liquid crystal polymer can be ≤2.0%, so that the foaming ratio can reach 0%. Furthermore, when the repeating unit, monomer and phenol end group content of the preferred liquid crystal polyester are increased, the thermal weight loss rate and the foaming ratio can be further reduced.

[0037] Table 1 continued: B-1 B-2 B-3 B-4 B-5 4-Hydroxybenzoic acid 45 45 40 45 2-Hydroxy-6-naphthoic acid 45 Terephthalic acid 17.5 30 27.5 27.5 Isophthalic acid 27.5 10 4,4'-Dihydroxybiphenyl 27.5 27.5 30 27.5 27.5 Hydroquinone Compression polymerization time, h 4.5 4.5 4.5 0.5 0.5 Melt viscosity, Pa.s 39.9 41.3 39.2 39.7 40.0 Phenol end group content, % 0.32 0.35 0.33 0.72 0.77 Thermal weight loss rate, % 2.53 2.14 3.06 2.34 2.50 Foaming ratio, % 33 12 85 28 31 It can be seen from the liquid crystal polymer B1-3 that when the repeating unit is not within the scope of the present invention, even if the phenol end group content is lower than 0.5%, the thermal weight loss rate is higher than 2% and the foaming ratio is high.

[0038] It can be seen from the liquid crystal polymer B4-5 that when the phenol end group content is greater than 0.5%, even if the repeating unit is within the scope of the present invention, the thermal weight loss is higher than 2% and the foaming ratio is high.

[0039] Table 1 continued: A-11 A-12 4-Hydroxybenzoic acid 45 2-Hydroxy-6-naphthoic acid 45 Terephthalic acid 27.5 27.5 Isophthalic acid 4,4'-Dihydroxybiphenyl 27.5 27.5 Hydroquinone Melt viscosity, Pa.s 39.8 39.6 Phenol end group content, % 0.43 0.38 Thermal weight loss rate, % 1.46 1.79 Foaming ratio, % 0 0 Table 2: Weight parts of each component of the liquid crystal polymer composition of the embodiment and comparative example and test results Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Liquid crystal polymer A-1 A-2 A-3 A-4 A-5 A-6 Liquid crystal polymer content 60 45 70 60 60 60 Fiberglass 40 55 40 40 40 talcum powder 22 Thermal weight loss rate, % 0.575 0.612 0.605 0.761 0.933 1.078 Foaming ratio, % 0 0 0 0 0 0 Table 2 continued: Example 7 Example 8 Example 9 Example 10 Embodiment 11 Example 12 Liquid crystal polymer designation A-7 A-8 A-9 A-10 A-11 A-12 Liquid crystal polymer content 60 60 60 60 60 60 Fiberglass 40 40 40 40 40 40 talcum powder Thermal weight loss rate, % 0.801 0.876 0.855 0.910 0.773 0.942 Foaming ratio, % 0 0 0 0 0 0 Table 2 continued: Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Liquid crystal polymer designation B-1 B-2 B-3 B-4 B-5 Liquid crystal polymer content 60 60 60 60 60 Fiberglass 40 40 40 40 40 talcum powder Thermal weight loss rate, % 1.516 1.396 1.892 1.329 1.499 Foaming ratio, % 38 27 58 32 30 It can be seen from the above examples and comparative examples that the liquid crystal polymer of the present invention, when applied to a composition, also has significantly better anti-foaming performance.

Claims

1. A liquid crystal polymer, characterized in that: In mole percent, it is derived from the following repeating units: -O-Ar1-CO-unit 45-75 mol%; -CO-Ar2-CO- units 12.5-27.5 mol%; -O-Ar3-O-unit 12.5-27.5mol%; -O-Ar1-CO- unit is derived from at least one of 4-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid; The -CO-Ar2-CO- unit is derived from terephthalic acid; The -O-Ar3-O- unit is derived from at least one of hydroquinone and 4,4'-dihydroxybiphenyl; Based on the total weight of the liquid crystal polymer, the phenol end group content is ≤0.5%.

2. The crystalline polymer according to claim 1, characterized in that The content of -O-Ar1-CO- unit is 45-65 mol%; the content of -CO-Ar2-CO- unit is 17.5-27.5 mol%; the content of -O-Ar3-O- unit is 17.5-27.5 mol%, and the content of phenol end groups is ≤0.4% based on the total weight of the liquid crystal polymer; more preferably, the content of -O-Ar1-CO- unit is 45-63 mol%; the content of -CO-Ar2-CO- unit is 18.5-27.5 mol%; the content of -O-Ar3-O- unit is 18.5-27.5 mol%, and the content of phenol end groups is ≤0.35% based on the total weight of the liquid crystal polymer.

3. The crystalline polymer according to claim 2, characterized in that The thermogravimetric loss rate is ≤2.0%, preferably the thermogravimetric loss rate is ≤1.8%, and more preferably the thermogravimetric loss rate is ≤1.7%.

4. The crystalline polymer according to claim 1, characterized in that The -O-Ar1-CO- unit is derived from 4-hydroxybenzoic acid, and the -O-Ar3-O- unit is derived from 4,4'-dihydroxybiphenyl.

5. The liquid crystal polymer according to claim 1, characterized in that The melt viscosity of the liquid crystal polyester is in the range of 10-200 Pa.s.

6. The method for polymerizing a liquid crystal polymer according to any one of claims 1 to 5, characterized in that: The following steps are involved: Acylation section, polycondensation section, decompression polycondensation section, solid phase viscosity increasing section.

7. The method for polymerizing a liquid crystal polymer according to claim 6, characterized in that: The polymerization method is: (1) Acylation stage: The monomers corresponding to the -O-Ar1-CO- unit and the -O-Ar3-O- unit, the acylating agent and the catalyst are simultaneously added into the reactor for acylation reaction at a temperature of 130-160°C for 1.5-5h; (2) Polycondensation stage: melt polycondense the acylated reactant in step (1) with the monomer corresponding to the -CO-Ar2-CO- unit, heat the temperature to 280°C at a heating rate of 0.3-1.5°C / min, control the heating rate so that the heating time in the 280-300°C heating stage is maintained at 1-3h, and finally continue to heat the temperature at a heating rate of 0.3-1.5°C / min to 10-30°C above the melting point, and continuously distill out by-products during the heating period; (3) Reduced pressure polymerization section: Reduced pressure polymerization is carried out, the target vacuum degree is 0.1 kPa to 40 kPa, the reduced pressure polymerization time is 3.5 to 6 hours, and the temperature of the prepolymer melt is finally controlled to be 10 to 30 °C above the melting point when discharged; (4) Solid phase viscosity increasing process: After reaching the target melt viscosity through a one-step melt polymerization method, the melt is discharged in a molten state, and after cooling, it is cut or crushed to obtain a liquid crystal polymer; The acylating agent is selected from at least one of acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, 2-ethylhexanoic anhydride, dichloroacetic anhydride, dibromoacetic anhydride, difluoroacetic anhydride, maleic anhydride, and succinic anhydride; the catalyst is selected from at least one of magnesium acetate, sodium acetate, stannous acetate, tetrabutyl titanate, lead acetate, potassium acetate, and antimony trioxide.

8. A liquid crystal polymer composition, characterized in that By weight, it includes the following components: 45-78 parts of the liquid crystal polymer according to any one of claims 1 to 5 or the liquid crystal polymer obtained by the preparation method according to any one of claims 6 to 7; 22-55 parts of reinforcement material; The reinforcing material is selected from at least one of fibrous reinforcing fillers and granular reinforcing fillers.

9. The liquid crystal polymer composition according to claim 8, characterized in that The fibrous reinforcing filler is selected from at least one of glass fiber, potassium titanate fiber, ceramic fiber, wollastonite fiber, metal carbide fiber, metal solidified fiber, asbestos fiber, aluminum oxide fiber, silicon carbide fiber, gypsum fiber, boron fiber, potassium titanate whisker, and aluminum borate whisker; the granular reinforcing filler is selected from at least one of talc, carbon black, gypsum, asbestos, zeolite, kaolin, montmorillonite, clay, hectorite, aluminosilicate, silicon dioxide, titanium oxide, aluminum oxide, zinc oxide, zirconium oxide, iron oxide, magnesium titanate, dolomite, aluminum sulfate, barium sulfate, magnesium sulfate, calcium carbonate, mica, quartz powder, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, glass beads, ceramic beads, boron nitride, and silicon carbide.

10. A component suitable for lead-free solder, characterized in that: The article is made using the liquid crystal polymer composition according to claim 8 or 9.