Liquid crystal polymer and preparation method thereof, liquid crystal composition, film and communication assembly

Abstract

The invention discloses a liquid crystal polymer and a preparation method thereof, a liquid crystal composition, a film and a communication assembly. The liquid crystal polymer is obtained by polymerizing lignin and monomers comprising hydroxyl aromatic acid, hydroxyl aromatic amine and aromatic dicarboxylic acid, and the liquid crystal polymer prepared by the invention can be dissolved in an aprotic solvent, so that the technical problem that a traditional liquid crystal polymer is difficult to process in the processing process is solved; according to the present invention, the application of the liquid crystal polymer in the high-frequency and high-speed communication device is achieved, the signal transmission capability of the communication device is improved, the prepared liquid crystal polymer has characteristics of extremely low water absorption and excellent heat resistance, and the reliability of the communication device can be improved.

Description

Technical Field

[0001] This application relates to the field of polymer technology, and in particular to liquid crystal polymers and their preparation methods, liquid crystal compositions, films and communication components. Background Technology

[0002] With the development of 5G technology, devices are exhibiting a trend towards high frequency and high speed, placing increasingly higher demands on their signal transmission capabilities, especially high-frequency signal transmission capabilities. Existing polyimide (PI) materials suffer from high dielectric constants and loss factors, high moisture absorption, and poor reliability, leading to severe high-frequency transmission losses and insufficient device reliability, making them unsuitable for current development trends. Liquid crystal polymers (LCPs), due to their unique molecular structure, have a lower dielectric constant than PI. If used in communication equipment, they could reduce signal transmission losses, making them a potential alternative to PI in 5G communication devices. However, LCPs are insoluble in solvents, making them difficult to process, which significantly limits their application in communication equipment. Summary of the Invention

[0003] Therefore, it is necessary to provide a liquid crystal polymer that can be dissolved in a solvent and used in communication devices for high-frequency and high-speed signal transmission.

[0004] In a first aspect, this application provides a liquid crystal polymer obtained by polymerization of monomers and lignin, wherein the monomers include hydroxy aromatic acids, hydroxy aromatic amines, and aromatic dicarboxylic acids.

[0005] In some embodiments, the molar ratio of the monomer to the lignin is (90-99):(1-10); and / or, the molar ratio of the hydroxy aromatic acid, the hydroxy aromatic amine, and the aromatic dicarboxylic acid is (40-70):(10-25):(10-30).

[0006] In some embodiments, the hydroxy aromatic acid includes one or more of 2-hydroxy-6-naphthoic acid and p-hydroxybenzoic acid; and / or, the hydroxy aromatic amine includes acetaminophen; and / or, the aromatic dicarboxylic acid includes one or more of terephthalic acid, isophthalic acid and 2,6-naphthoic acid; and / or, the lignin includes one or more of syringyl lignin, guaiacyl lignin and p-hydroxyphenyl lignin.

[0007] In some embodiments, the liquid crystal polymer is obtained by polymerization of monomers and lignin under conditions of a catalyst and an acylating agent;

[0008] Optionally, the catalyst comprises an alkali metal salt; more preferably, the alkali metal salt comprises one or more of potassium acetate, potassium aromatic salt, magnesium acetate, magnesium aromatic salt, calcium acetate, calcium aromatic salt, cobalt acetate, and cobalt aromatic salt.

[0009] Optionally, the acylating agent includes acetic anhydride.

[0010] Secondly, this application also provides a method for preparing a liquid crystal polymer, comprising the following steps:

[0011] Hydroxy aromatic acids, aromatic dicarboxylic acids, catalysts, and acylating agents are mixed to form a first mixture;

[0012] Add hydroxy aromatic amine and lignin to the first mixture to form a second mixture;

[0013] In an inert gas atmosphere, the second mixture is subjected to a first reaction by heating to 140°C-160°C, and then subjected to a second reaction by heating to 290°C-310°C to form a liquid crystal polyester prepolymer.

[0014] The liquid crystal polyester prepolymer was subjected to a solid-state reaction to prepare a liquid crystal polymer.

[0015] In some embodiments, the inert gas includes one or more of nitrogen, argon, and helium; and / or, the first heating is to raise the second mixture from room temperature to 140°C-160°C within 20 min-40 min; and / or, the first reaction time is 1 h-3 h; and / or, the second heating is to raise the mixture from 140°C-160°C to 290°C-310°C at a heating rate of 1°C / min-3°C / min; and / or, the second reaction time is 2 h-4 h; and / or, the solid-phase reaction temperature is 275°C-285°C; and / or, the solid-phase reaction time is 5 h-8 h.

[0016] Thirdly, this application also provides a film prepared by a liquid crystal polymer, wherein the liquid crystal polymer includes the liquid crystal polymer provided in the first aspect or the liquid crystal polymer prepared by the preparation method provided in the second aspect.

[0017] Fourthly, this application also provides a method for preparing a membrane, comprising the following steps:

[0018] The liquid crystal polymer is dissolved in a solvent to form a liquid crystal polymer solution;

[0019] The liquid crystal polymer solution is coated onto the surface of a substrate, dried, and cured to form a film on the surface of the substrate.

[0020] In some embodiments, the solvent comprises an aprotic solvent; optionally, the aprotic solvent comprises one or more of N-methylpyrrolidone and N,N-dimethylacetamide; and / or,

[0021] The drying temperature is 50℃-150℃; and / or,

[0022] The curing temperature is 180℃-250℃.

[0023] Fifthly, this application also provides a communication component, the communication component comprising a main substrate and a film provided in the third aspect for encapsulating the main substrate.

[0024] Compared with traditional technologies, the beneficial effects of the technical solution in this application include:

[0025] This application provides a liquid crystal polymer that is soluble in a solvent. The liquid crystal polymer obtained by polymerizing monomers including hydroxy aromatic acids, hydroxy aromatic amines and aromatic dicarboxylic acids with lignin is soluble in a solvent, thereby solving the technical problem of difficult processing of liquid crystal polymers. At the same time, it can maintain the performance advantages of low dielectric constant, low water absorption and excellent heat resistance, thereby realizing its application in high-frequency and high-speed communication equipment and improving the signal transmission capability and reliability of communication equipment. Detailed Implementation

[0026] To facilitate understanding of this application, preferred embodiments are provided below to provide a more complete description of the application. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a thorough and complete understanding of the disclosure of this application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0028] As used herein, "optional," "optional," and "optional" refer to either "with" or "without" parallel options. If multiple "optional" entries appear in a technical solution, each "optional" entry is independent unless otherwise specified and there are no contradictions or mutual constraints. The term "and / or" as used herein includes any and all combinations of one or more related listed items. Unless otherwise specified, "multiple," "multiple," etc., as used herein refer to a quantity greater than 2 or equal to 2; for example, "one or more" indicates one, two, or more than two. In open-ended technical features or solutions described herein using words such as "containing," "including," and "comprising," unless otherwise specified, additional members beyond the listed members are not excluded. This can be considered as providing both a closed-ended feature or solution consisting of the listed members and an open-ended feature or solution that includes additional members beyond the listed members.

[0029] In this application, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0030] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0031] With the development of 5G communication, the commonly used polyimide (PI) suffers from severe losses in high-frequency transmission due to its high dielectric properties, which limits its use in high-frequency equipment. In addition, it also has high moisture absorption and poor reliability, which affects the long-term stability of the equipment.

[0032] Liquid crystal materials are materials with a special molecular structure. Compared to polyimide (PI), they have a lower dielectric constant, which can reduce high-frequency transmission loss and improve high-frequency transmission capability. However, their insolubility in solvents limits their processing, especially making it difficult to apply them to equipment through casting, coating, and other processing methods. Currently, there are also research reports on soluble liquid crystal polymers. Although these polymers can dissolve in some solvents, improving their processing performance, they suffer from unstable dielectric constants and hygroscopicity, insufficient heat resistance, and unreliable reliability.

[0033] Therefore, this application aims to provide a soluble liquid crystal polymer that has both a low and stable dielectric constant and moisture absorption, as well as excellent heat resistance, to improve the signal transmission performance and reliability of high-frequency devices.

[0034] In a first aspect, this application provides a liquid crystal polymer, which is obtained by polymerization of monomers and lignin. The liquid crystal polymer is formed by polymerization of monomers containing hydroxy aromatic acids, hydroxy aromatic amines and aromatic dicarboxylic acids with lignin. The liquid crystal polymer is soluble in aprotic solvents, solving the technical problem that traditional liquid crystal polymers cannot be dissolved in solvents. This achieves good processing performance of the liquid crystal polymer, especially in communication equipment. Processing methods such as casting and coating are used to improve the high-frequency signal transmission capability, heat resistance, low moisture absorption and reliability of communication equipment.

[0035] Lignin is a natural macromolecule containing aromatic rings, possessing a unique and complex aromatic and aliphatic backbone structure and abundant functional groups suitable for functionalization. It can serve as an alternative to petroleum-based phenolic polymers and is one of the most attractive derivative macromolecules and natural substances for the development of sustainable and functional materials.

[0036] Lignin is a phenolic polymer composed of three alcohol monomers: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol. From a chemical perspective, lignin is a polymer formed by the random polymerization of highly substituted phenylpropane units. Based on the different monomers, lignin can be divided into three types: syringyl lignin (S-lignin), polymerized from syringylpropane monomers; guaiacyl lignin (G-lignin), polymerized from guaiacylpropane monomers; and para-hydroxy-phenyl lignin (H-lignin), polymerized from para-hydroxy-phenylpropane monomers. The specific molecular structures are shown below:

[0037]

[0038] This application, by polymerizing monomers with specific structures with lignin, achieves two advantages: firstly, the prepared liquid crystal polymer can be completely dissolved in a solvent, overcoming the limitations of traditional liquid crystal polymers in communication equipment applications; secondly, the liquid crystal polymer prepared by polymerizing monomers with specific structures with lignin exhibits excellent processing properties, with superior melting characteristics, glass transition temperature, and viscosity, resulting in excellent processing performance. Furthermore, the overall performance of the liquid crystal polymer prepared by polymerizing monomers with specific structures with lignin is significantly improved, which is also more beneficial for enhancing the performance of high-frequency and high-speed communication equipment.

[0039] In some embodiments, the molar ratio of the monomer to the lignin is (90-99):(1-10), including but not limited to 90:10, 91:9, 92:8, 93:7, 94:6, 95:5, 96:4, 97:3, 98:2, 99:1, or any combination thereof and values ​​within that range. It is understood that the liquid crystal polymer is obtained by polymerizing 90 mol%-99 mol% of the monomer and 1 mol%-10 mol% of the lignin. Further, the molar ratio of the monomer to the lignin is (90-95):(5-10). It is understood that the liquid crystal polymer is obtained by polymerizing 90 mol%-95 mol% of the monomer and 5 mol%-10 mol% of the lignin.

[0040] In some embodiments, the molar ratio of the hydroxy aromatic acid, the hydroxy aromatic amine, and the aromatic dicarboxylic acid is (40-70):(10-25):(10-30), including but not limited to 40:10:10, 40:10:30, 40:20:30, 50:20:25, 60:10:20, 70:10:10, 70:10:15, 70:10:30, or any of the foregoing ranges and values ​​within those ranges. Further, the molar ratio of the hydroxy aromatic acid, the hydroxy aromatic amine, and the aromatic dicarboxylic acid is (40-70):(10-20):(15-30).

[0041] In some embodiments, the hydroxy aromatic acid comprises 40 mol%-70 mol%, the hydroxy aromatic amine comprises 10 mol%-25 mol%, and the aromatic dicarboxylic acid comprises 10 mol%-30 mol%, based on the molar percentage of the total monomer and lignin. Further, the hydroxy aromatic acid comprises 40 mol%-70 mol%, the hydroxy aromatic amine comprises 10 mol%-20 mol%, and the aromatic dicarboxylic acid comprises 15 mol%-30 mol%, based on the molar percentage of the total monomer and lignin.

[0042] As a non-limiting example, the hydroxy aromatic acid includes one or more of 2-hydroxy-6-naphthoic acid and p-hydroxybenzoic acid. As a non-limiting example, the hydroxy aromatic amine includes acetaminophen. As a non-limiting example, the aromatic dicarboxylic acid includes one or more of terephthalic acid, isophthalic acid, and 2,6-naphthoic acid. As a non-limiting example, the lignin includes one or more of syringyl lignin, guaiacyl lignin, and p-hydroxyphenyl lignin.

[0043] In some embodiments, the liquid crystal polymer is obtained by polymerization of 2-hydroxy-6-naphthoic acid (HNA), acetaminophen (APAP), isophthalic acid (IPA), and lignin. In some preferred embodiments, the liquid crystal polymer is obtained by polymerization of 2-hydroxy-6-naphthoic acid (HNA), acetaminophen (APAP), isophthalic acid (IPA), and H-lignin, which can further improve the overall performance of the liquid crystal polymer.

[0044] In some embodiments, the liquid crystal polymer is obtained by polymerizing monomers and lignin under the conditions of a catalyst and an acylation agent. The preparation mechanism of the liquid crystal polymer in this application mainly includes two stages: activation and polymerization. In the activation stage, the acylation agent reacts with the carboxyl groups in the raw materials through an acylation reaction, while the catalyst activates the hydroxyl groups in the raw materials, thereby activating all the functional groups in the raw materials and providing more favorable reaction conditions for the subsequent polymerization stage. In the polymerization stage, the raw materials activated in the activation stage undergo a stepwise polycondensation reaction to form a liquid crystal phase, ultimately forming the liquid crystal polymer.

[0045] In some embodiments, the catalyst comprises an alkali metal salt. As a non-limiting example, the alkali metal salt includes one or more of potassium (K) acetate, potassium (K) aromatic salt, magnesium (Mg) acetate, magnesium (Mg) aromatic salt, calcium (Ca) acetate, calcium (Ca) aromatic salt, cobalt (Co) acetate, and cobalt (Co) aromatic salt.

[0046] In some embodiments, the acylating agent includes acetic anhydride.

[0047] In some embodiments, the amount of catalyst added, based on the total amount of the monomer and the lignin, is 50 wtppm to 80 wtppm, including but not limited to 50 wtppm, 55 wtppm, 60 wtppm, 65 wtppm, 70 wtppm, 75 wtppm, 80 wtppm or any combination thereof and values ​​within such ranges.

[0048] Secondly, this application also provides a method for preparing a liquid crystal polymer, comprising the following steps:

[0049] S10. Hydroxy aromatic acid, aromatic dicarboxylic acid, catalyst, and acylating agent are mixed to form the first mixture.

[0050] S20. Add hydroxy aromatic amine and lignin to the first mixture to form a second mixture.

[0051] S30. Under an inert gas atmosphere, the second mixture is subjected to a first reaction by heating to 140°C-160°C, and then subjected to a second reaction by heating to 290°C-310°C to form a liquid crystal polyester prepolymer.

[0052] S40. The liquid crystal polyester prepolymer is subjected to a solid-state reaction to prepare a liquid crystal polymer.

[0053] In some embodiments, the composition and amount of the hydroxy aromatic acid, hydroxy aromatic amine, aromatic dicarboxylic acid, lignin, catalyst, and acylation agent are the same as in the first aspect.

[0054] In some embodiments, the inert gas includes one or more of nitrogen, argon, and helium.

[0055] As a non-limiting example, the temperature of the first reaction includes, but is not limited to, 140°C, 145°C, 150°C, 155°C, 160°C, or any combination thereof and values ​​within such ranges.

[0056] As a non-limiting example, the temperature of the second reaction includes, but is not limited to, 290°C, 295°C, 300°C, 305°C, 310°C, or any combination thereof and values ​​within such ranges.

[0057] In some embodiments, the first heating is to raise the temperature of the second mixture from room temperature to 140°C-160°C within 20-40 minutes.

[0058] In some embodiments, the time for the first reaction is 1-3 hours, including but not limited to 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or any combination thereof and values ​​within that range.

[0059] In some embodiments, the second heating is performed by raising the mixture from 140°C-160°C to 290°C-310°C at a heating rate of 1°C / min-3°C / min. As a non-limiting example, the heating rate includes, but is not limited to, 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, or any range thereof and values ​​within that range.

[0060] In some embodiments, the time for the second reaction is 2h-4h, including but not limited to 2h, 2.5h, 3h, 3.5h, 4h or any of the foregoing ranges and values ​​within that range.

[0061] In some embodiments, the temperature of the solid-phase reaction is 275°C-285°C, including but not limited to 275°C, 278°C, 280°C, 282°C, 285°C, or any of the foregoing ranges and values ​​within that range.

[0062] In some embodiments, the solid-phase reaction time is 5h-8h, including but not limited to 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h or any of the foregoing ranges and values ​​within that range.

[0063] In some embodiments, step S40 further includes cooling and pulverizing the liquid crystal polyester prepolymer before the solid-state reaction. It is understood that cooling is a process of pre-curing the liquid crystal polyester prepolymer, and the cooling temperature can be room temperature.

[0064] In some embodiments, the solid-phase reaction in step S40 is carried out in an inert gas atmosphere. As a non-limiting example, the inert gas includes one or more of nitrogen, argon, and helium.

[0065] Thirdly, this application also provides a film prepared by a liquid crystal polymer, wherein the liquid crystal polymer includes the liquid crystal polymer provided in the first aspect or the liquid crystal polymer prepared by the preparation method provided in the second aspect.

[0066] Fourthly, this application also provides a method for preparing a membrane, comprising the following steps:

[0067] T10. Dissolve the liquid crystal polymer in a solvent to form a liquid crystal polymer solution.

[0068] T20. The liquid crystal polymer solution is coated onto the surface of the substrate, dried, and cured to form a film on the surface of the substrate.

[0069] In some embodiments, the solvent comprises an aprotic solvent. Further optionally, the aprotic solvent comprises one or more of N-methylpyrrolidone and N,N-dimethylacetamide.

[0070] In some embodiments, the drying temperature is 50°C-150°C, including but not limited to 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or any combination thereof and values ​​within that range.

[0071] In some embodiments, the curing temperature is 180°C-250°C, including but not limited to 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C or any of the foregoing ranges and values ​​within those ranges.

[0072] Fifthly, this application also provides a communication component, the communication component comprising a main substrate and a membrane provided in the fourth aspect for encapsulating the main substrate.

[0073] It is understood that encapsulation can be achieved by covering the surface of the host substrate with a film.

[0074] It is understood that the communication components include one or more of the following: 5G base station housing, filter, antenna vibrator, mobile phone back cover and mid-frame, microwave and millimeter-wave radio frequency front-end circuits.

[0075] It should be noted that experimental methods in the following embodiments of this application, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the embodiments are commercially available products, or can be prepared by those skilled in the art using known methods.

[0076] The types and sources of some of the raw materials and reagents involved in the specific embodiments of this application are as follows:

[0077] S-lignin, syringyl lignin monomer (sinapyl alcohol CAS: 537-33-7).

[0078] G-lignin, guaiac-based lignin monomer (coniferyl alcohol CAS:32811-40-8).

[0079] H-lignin, p-hydroxyphenyl lignin monomer (p-coumaryl alcohol CAS: 3690-05-9).

[0080] Example 1

[0081] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0082] The amounts of monomers and lignin added are:

[0083] 2-Hydroxy-6-naphthoic acid (HNA) 50 mol%

[0084] Acetaminophen (APAP) 20 mol%

[0085] IPA (isophthalic acid) 25 mol%, and

[0086] H-lignin 5 mol%.

[0087] Based on the above liquid crystal polymer formulation, the preparation process steps for the liquid crystal polymer are as follows:

[0088] In a reactor equipped with a stirring device, a nitrogen inlet pipe, a thermometer, and a reflux cooler, HNA, IPA, and potassium acetate (the amount of potassium acetate added is 70 wtppm compared to the total amount of monomers and lignin) are added and mixed. After mixing, an appropriate amount of acetic anhydride is added and stirred for 2 hours. Then, APAP and H-lignin are added.

[0089] Nitrogen gas is injected into the reactor to make the internal space of the reactor inactive. Then, the temperature is raised to 150°C within 30 minutes and refluxed for 2 hours to remove byproducts such as acetic acid. Then, the reactor temperature is raised to 300°C at a rate of 2°C / min and maintained at 300°C for 3 hours. Finally, the liquid crystal polyester prepolymer is discharged to the outside of the reactor.

[0090] The liquid crystal polyester prepolymer was recovered and cooled to solidify. The prepolymer was then pulverized into powder using a pulverizer. The liquid crystal polyester prepolymer powder with uniform particle size was fed into a solid-phase reactor. While nitrogen was flowing in, a solid-phase reaction was carried out at 280°C for 6 hours. After the reaction was completed, the reactor was cooled to room temperature to obtain liquid crystal polyester resin.

[0091] Example 2

[0092] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0093] The amounts of monomers and lignin added are:

[0094] 2-Hydroxy-6-naphthoic acid (HNA) 70 mol%

[0095] Acetaminophen (APAP) 10 mol%

[0096] IPA (isophthalic acid) 15 mol%, and

[0097] H-lignin 5 mol%.

[0098] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0099] Example 3

[0100] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0101] The amounts of monomers and lignin added are:

[0102] 2-Hydroxy-6-naphthoic acid (HNA) 40 mol%

[0103] Acetaminophen (APAP) 20 mol%

[0104] IPA (isophthalic acid) 30 mol%, and

[0105] 10 mol of H-lignin monomer.

[0106] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0107] Example 4

[0108] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0109] The amounts of monomers and lignin added are:

[0110] 2-Hydroxy-6-naphthoic acid (HNA) 70 mol%

[0111] Acetaminophen (APAP) 10 mol%

[0112] IPA (isophthalic acid) 15 mol%, and

[0113] 5 mol of S-lignin monomer.

[0114] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0115] Example 5

[0116] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0117] The amounts of monomers and lignin added are:

[0118] 2-Hydroxy-6-naphthoic acid (HNA) 70 mol%

[0119] Acetaminophen (APAP) 10 mol%

[0120] IPA (isophthalic acid) 15 mol%, and

[0121] G-lignin 5 mol%.

[0122] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0123] Example 6

[0124] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0125] The amounts of monomers and lignin added are:

[0126] 2-Hydroxy-6-naphthoic acid (HNA) 50 mol%

[0127] Acetaminophen (APAP) 24 mol%

[0128] isophthalic acid (IPA) 25 mol%, and

[0129] 1 mol% H-lignin.

[0130] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0131] Example 7

[0132] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0133] The amounts of monomers and lignin added are:

[0134] 2-Hydroxy-6-naphthoic acid (HNA) 40 mol%

[0135] Acetaminophen (APAP) 20 mol%

[0136] Terephthalic acid (TPA) 30 mol%, and

[0137] 10 mol of H-lignin.

[0138] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0139] Example 8

[0140] The raw material composition for preparing the liquid crystal polymer in this embodiment is as follows:

[0141] The amounts of monomers and lignin added are:

[0142] p-Hydroxybenzoic acid (HBA) 40 mol%

[0143] Acetaminophen (APAP) 20 mol%

[0144] IPA (isophthalic acid) 30 mol%, and

[0145] 10 mol of H-lignin.

[0146] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0147] Comparative Example 1

[0148] The raw material composition for preparing the liquid crystal polymer in this comparative example is as follows:

[0149] The amount of monomer added is:

[0150] 2-Hydroxy-6-naphthoic acid (HNA) 27 mol%, and

[0151] p-Hydroxybenzoic acid (HBA) 73 mol%

[0152] The process steps for preparing the liquid crystal polymer are basically the same as those in Example 1, based on the composition scheme of the liquid crystal polymer described above.

[0153] Comparative Example 2

[0154] The raw material composition for preparing the liquid crystal polymer in this comparative example is as follows:

[0155] The amount of monomer added is:

[0156] 2-Hydroxy-6-naphthoic acid (HNA) 40 mol%

[0157] Acetaminophen (APAP) 30 mol%, and

[0158] IPA (isophthalic acid) 30 mol%.

[0159] The process steps for preparing the liquid crystal polymer according to the above composition scheme are the same as those in Example 1.

[0160] Experimental Example 1: Solubility Test of Liquid Crystal Polymers

[0161] The liquid crystal polymers prepared in Examples 1-8 and Comparative Examples 1-2 were subjected to solubility tests. The test method was as follows: the liquid crystal polymer samples were dissolved in a solvent, and whether they dissolved was observed. The test solvent was N-methylpyrrolidone (NMP). The specific results are expressed as the maximum percentage of samples that can dissolve in NMP. The results are shown in Table 1.

[0162] Table 1: Solubility of liquid crystal polymers in solvents

[0163]

[0164] As shown in Table 1, the liquid crystal composition prepared in this application can be dissolved in aprotic solvents, which facilitates processing and molding, and allows for better application in high-frequency and high-speed communication equipment, thereby improving the signal transmission performance and reliability of the communication equipment.

[0165] Experimental Example 2: Processing Performance Test of Liquid Crystal Polymers

[0166] The liquid crystal polymers prepared in Examples 1-8 and Comparative Examples 1-2 were subjected to processing performance tests. The test parameters included melting temperature, glass transition temperature, and solution viscosity. The specific test methods are as follows:

[0167] (1) Melting temperature and glass transition temperature: tested using DSC (differential calorimeter).

[0168] (2) Solution viscosity: measured using a Brookfield viscometer.

[0169] The specific results are shown in Table 2:

[0170] Table 2: Test results of processing performance of liquid crystal polymers

[0171]

[0172] Note: "-" indicates that data could not be detected.

[0173] As shown in Table 2, the liquid crystal composition prepared in this application has a suitable viscosity, can be better processed into films, and has excellent processing and molding properties.

[0174] Experimental Example 3: Physical and Chemical Properties Testing of Liquid Crystal Polymers

[0175] The liquid crystal polymers prepared in Examples 1-8 and Comparative Examples 1-2 were subjected to physicochemical property tests. The test indicators included dielectric constant and water absorption rate. The specific test methods are as follows:

[0176] (1) Dielectric constant: The test standard is ASTM D150.

[0177] (2) Water absorption rate: The test standard is GBT1034-2008.

[0178] The specific results are shown in Table 3:

[0179] Table 3: Test results of the physicochemical properties of liquid crystal polymers

[0180]

[0181] As shown in Table 3, the liquid crystal composition prepared in this application has a low dielectric constant, extremely low water absorption rate, and excellent heat resistance. When applied in high-frequency and high-speed communication equipment, it can significantly improve the transmission of high-frequency signals, reduce signal loss, and improve the reliability of the equipment.

[0182] Test Example 4

[0183] This experimental example provides the preparation process of the liquid crystal film, the specific process is as follows:

[0184] Preparation of LCP solution: The liquid crystal polymers prepared in Examples 1 to 6 were dissolved in a special aprotic solvent (such as NMP or DMAc) to prepare LCP solutions with a mass concentration of 10%.

[0185] The LCP solution is then uniformly coated onto a substrate (such as PET film or stainless steel strip) using a doctor blade or coating head to form a wet film.

[0186] The wet film is placed in a 100°C hot air oven to gradually evaporate the solvent and form a dry film. The dry film is then heated to 200°C for cross-linking and curing, and finally peeled off from the substrate to obtain an LCP film.

[0187] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0188] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A liquid crystal polymer, characterized in that, The liquid crystal polymer is obtained by polymerization of monomers and lignin, wherein the monomers include hydroxy aromatic acids, hydroxy aromatic amines and aromatic dicarboxylic acids.

2. The liquid crystal polymer according to claim 1, characterized in that, The molar ratio of the monomer to the lignin is (90-99):(1-10); and / or the molar ratio of the hydroxy aromatic acid, the hydroxy aromatic amine, and the aromatic dicarboxylic acid is (40-70):(10-25):(10-30).

3. The liquid crystal polymer according to claim 1, characterized in that, The hydroxy aromatic acid includes one or more of 2-hydroxy-6-naphthoic acid and p-hydroxybenzoic acid; and / or, the hydroxy aromatic amine includes acetaminophen; and / or, the aromatic dicarboxylic acid includes one or more of terephthalic acid, isophthalic acid and 2,6-naphthoic acid; and / or, the lignin monomer includes one or more of syringyl lignin monomer, guaiacyl lignin monomer and p-hydroxyphenyl lignin monomer.

4. The liquid crystal polymer according to any one of claims 1 to 3, characterized in that, The liquid crystal polymer is obtained by polymerization of monomers and lignin under conditions of catalyst and acylating agent. Optionally, the catalyst comprises an alkali metal salt; more preferably, the alkali metal salt comprises one or more of potassium acetate, potassium aromatic salt, magnesium acetate, magnesium aromatic salt, calcium acetate, calcium aromatic salt, cobalt acetate, and cobalt aromatic salt. Optionally, the acylating agent includes acetic anhydride.

5. A method for preparing a liquid crystal polymer, characterized in that, Includes the following steps: Hydroxy aromatic acids, aromatic dicarboxylic acids, catalysts, and acylating agents are mixed to form a first mixture; Add hydroxy aromatic amine and lignin to the first mixture to form a second mixture; In an inert gas atmosphere, the second mixture is subjected to a first reaction by heating to 140°C-160°C, and then subjected to a second reaction by heating to 290°C-310°C to form a liquid crystal polyester prepolymer. The liquid crystal polyester prepolymer was subjected to a solid-state reaction to prepare a liquid crystal polymer.

6. The method for preparing the liquid crystal polymer according to claim 5, characterized in that, The inert gas includes one or more of nitrogen, argon, and helium; and / or, the first heating is to raise the second mixture from room temperature to 140℃-160℃ within 20min-40min; and / or, the first reaction time is 1h-3h; and / or, the second heating is to raise the mixture from 140℃-160℃ to 290℃-310℃ at a heating rate of 1℃ / min-3℃ / min; and / or, the second reaction time is 2h-4h; and / or, the solid-phase reaction temperature is 275℃-285℃; and / or, the solid-phase reaction time is 5h-8h.

7. A membrane, characterized in that, The film is prepared by a liquid crystal polymer, which includes the liquid crystal polymer according to any one of claims 1 to 4 or the liquid crystal polymer prepared by the preparation method according to claim 5 or 6.

8. The method for preparing the membrane according to claim 7, characterized in that, Includes the following steps: The liquid crystal polymer is dissolved in a solvent to form a liquid crystal polymer solution; The liquid crystal polymer solution is coated onto the surface of a substrate, dried, and cured to form a film on the surface of the substrate.

9. The method for preparing the membrane according to claim 8, characterized in that, The solvent includes an aprotic solvent; optionally, the aprotic solvent includes one or more of N-methylpyrrolidone and N,N-dimethylacetamide; and / or, The drying temperature is 50℃-150℃; and / or, The curing temperature is 180℃-250℃.

10. A communication component, characterized in that, The communication component includes a main substrate and a membrane as described in claim 9 that encapsulates the main substrate.

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