A high thermal conductivity liquid crystal polyester composite material, its preparation method and application

Abstract

The present invention provides a high thermal conductivity liquid crystal polyester composite material and a preparation method and application thereof. The method first prepares a diol containing a biphenyl monomer, and then gradually condenses the diol monomer and 5-hydroxyisophthalic acid in an equal molar ratio in the presence of countless zinc acetate and antimony trioxide as catalysts to prepare a liquid crystal polyester as a matrix material containing a hydrogen bond donor. Graphene oxide is used as a filler, and a certain amount of graphene oxide is added to tetrahydrofuran and the synthesized liquid crystal polyester is fully stirred and then ultrasonically dispersed. The solvent is dried in a vacuum oven or vacuum-assisted filtration is used to remove the solvent, and then hot-pressed to obtain a high thermal conductivity liquid crystal polyester composite material. Its vertical surface thermal conductivity can reach 0.624W m ‑1 K ‑1 The thermal conductivity in the horizontal direction can reach 1.711W m ‑1 K ‑1 .

Description

Technical Field

[0001] The present invention relates to the field of thermally conductive composite materials, and particularly to a high thermally conductive liquid crystal polyester composite material, a preparation method thereof and an application thereof. Background Art

[0002] Due to the continuous miniaturization of devices and the continuous increase in device density, thermal management is becoming one of the most critical challenges in modern electronic products. The high demand for efficient heat dissipation in flexible electronic products has promoted the research on thermally conductive polymers. Liquid crystal polymers reduce phonon scattering and increase the thermal conductivity of polymers due to their special orientation arrangement. Currently, the research on intrinsically thermally conductive thermoplastics mainly focuses on enhancing the intermolecular interaction between polymer chains. Since carbon-based materials exhibit excellent high thermal conductivity, light weight and easy processing and molding, they are used to prepare thermally conductive composite materials. Among them, graphene has excellent thermal conductivity and light weight, meeting the development direction of the modern electronic device industry - the heat dissipation requirements of being thin, light, short and small. The problem of poor interfacial compatibility of composite materials severely limits the improvement efficiency of thermal conductivity. Summary of the Invention

[0003] An object of the present invention is to overcome the deficiencies of the prior art and provide a high thermally conductive liquid crystal polyester composite material.

[0004] Another object of the present invention is to provide a liquid crystal polyester containing a hydrogen bond donor.

[0005] Another object of the present invention is to provide a preparation method of the above-mentioned high thermally conductive liquid crystal polyester composite material.

[0006] Another object of the present invention is to provide the applications of the above-mentioned liquid crystal polyester containing a hydrogen bond donor and the high thermally conductive liquid crystal polyester composite material.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A liquid crystal polyester containing a hydrogen bond donor, and its structural formula is shown as Formula I:

[0009]

[0010] The preparation method of the above-mentioned liquid crystal polyester containing a hydrogen bond donor includes the following steps:

[0011] (1) Reacting a haloalcohol, biphenol and anhydrous potassium carbonate by refluxing under a protective atmosphere, adding water after cooling, filtering, neutralizing, washing with water and drying to obtain biphenyl dihexanol;

[0012] (2) Mixing biphenyl dihexanol and 5-hydroxyisophthalic acid, adding a catalyst and heating for polycondensation reaction, and then continuously heating the reaction while filtering to obtain a liquid crystal polyester containing a hydrogen bond donor.

[0013] The halogenated alcohol is at least one of 2-bromoethanol, 3-chloro-1-propanol, 4-chlorobutanol or 6-chlorohexanol.

[0014] The molar ratio of the halogenated alcohol to biphenol is 2-4:1; preferably 3:1.

[0015] The protective atmosphere is a nitrogen atmosphere.

[0016] The conditions for the reflux reaction are condensation reflux for 20-30 h; preferably condensation reflux for 24 h.

[0017] The cooling is to cool to room temperature.

[0018] The neutralization is to adjust the pH to 1 by adding hydrochloric acid.

[0019] The conditions for the drying are drying at 70-90 °C for 20-30 h; preferably drying at 80 °C for 24 h.

[0020] The molar ratio of the biphenyldihexanol to 5-hydroxyisophthalic acid is 1-2:1-2; preferably 1:1.

[0021] The catalyst is anhydrous zinc acetate and antimony trioxide.

[0022] The mass of the anhydrous zinc acetate is 0.1-0.3% of the total mass of the reaction system; preferably 0.2%.

[0023] The mass of the antimony trioxide is 0.2-0.4% of the total mass of the reaction system; preferably 0.3%.

[0024] The conditions for the heating polycondensation reaction are reaction at 150-200 °C for 2-4 h; preferably reaction at 180 °C for 3 h.

[0025] The conditions for the suction filtration are that the vacuum degree is lower than 30 Pa.

[0026] The conditions for the continued heating reaction are reaction at 150-200 °C for 2-4 h; preferably reaction at 190 °C for 3 h.

[0027] A preparation method of a high thermal conductivity liquid crystal polyester composite material comprises the following steps:

[0028] Dissolve graphene oxide and a liquid crystal polyester containing a hydrogen bond donor in tetrahydrofuran, stir, ultrasonically disperse, dry, and then obtain a high thermal conductivity liquid crystal polyester composite material through hot pressing.

[0029] The CAS number of the graphene oxide is 7782-45-5.

[0030] The stirring time is 3 to 5 h; preferably 4 h.

[0031] The ultrasonic dispersion time is 3 to 5 h; preferably 4 h.

[0032] The hot pressing conditions are hot pressing at 150 to 200 °C for 8 to 15 min; preferably hot pressing at 160 °C for 10 min.

[0033] The application of the above-mentioned liquid crystal polyester containing a hydrogen bond donor and the high thermal conductivity liquid crystal polyester composite material in the preparation of electronic devices.

[0034] The application of the above-mentioned liquid crystal polyester containing a hydrogen bond donor and the high thermal conductivity liquid crystal polyester composite material as a heat dissipation material for electronic devices.

[0035] The present invention has the following advantages and effects compared with the prior art:

[0036] (1) In the thermal conductive composite material prepared by the present invention, the synthesized liquid crystal polyester contains a hydrogen bond donor and forms a hydrogen bond with graphene oxide containing a hydrogen bond acceptor, so that the compatibility between graphene oxide and polyester is better, and the interfacial thermal resistance between polyester and graphene is reduced.

[0037] (2) For the thermal conductive composite material prepared by the present invention, the matrix is a thermoplastic polymer, which is easy to mold, and the composite material preparation process is simple. After hot pressing, the matrix and the filler are more closely bonded, so that the thermal conductivity of the liquid crystal polyester composite material is greatly improved. Description of the Drawings

[0038] Figure 1 It is the infrared spectrum of the polymer synthesized and the composite material prepared in the examples; wherein the polyester is the liquid crystal polyester containing a hydrogen bond donor in Example 1, 10% GO is the high thermal conductivity liquid crystal polyester composite material in Example 2, and 20% GO is the high thermal conductivity liquid crystal polyester composite material in Example 3. Detailed Embodiments

[0039] The present invention will be further described in detail below with reference to the embodiments and the drawings, but the embodiments of the present invention are not limited thereto.

[0040] If the specific test conditions are not specified in the following implementation examples, they are usually in accordance with the conventional test conditions or the test conditions recommended by the reagent company. The materials, reagents, etc. used, unless otherwise specified, are all reagents and materials obtained from commercial channels.

[0041] Example 1

[0042] This example provides a high thermal conductivity liquid crystal polyester composite material and a preparation method thereof.

[0043] (1) Place 40 ml of 6-chlorohexanol (halohydrin), 18.6 g of biphenol and 124 g of anhydrous potassium carbonate in a 250 ml three-necked flask. Under nitrogen protection, after refluxing for 24 h, cool the reactants to room temperature, add deionized water and stir, then perform suction filtration to remove the solvent. Add excessive hydrochloric acid to react with the excess potassium carbonate, wash with water multiple times, and then dry the obtained product in a vacuum oven at 80 °C for 24 h to obtain biphenyl dihexanol;

[0044] (2) Polycondense 3.54 g of biphenyl dihexanol and 1.8 g of 5-hydroxyisophthalic acid. The reaction conditions are as follows: add 0.011 g of anhydrous zinc acetate and 0.016 g of antimony trioxide, react at 180 °C for 3 h, slowly raise the temperature to 190 °C, then reduce the system vacuum degree (below 30 Pa) through vacuum suction filtration, and simultaneously remove the water and small molecules in the system to make the polycondensation reaction proceed in the forward direction. Continue to react at 190 °C for 3 hours, then stop the reaction, take out the product, and obtain a liquid crystal polyester containing a hydrogen bond donor, and its structural formula is as shown in Formula I.

[0045]

[0046] Characterize and test the prepared liquid crystal polyester containing a hydrogen bond donor, and detect the thermal conductivity in each direction. The experimental data show that the thermal conductivity in the vertical direction is 0.296 Wm-1k-1, and use an infrared spectrometer to detect the material, and its infrared spectrum is as Figure 1 shown.

[0047] Example 2

[0048] Dissolve 0.1 g of graphene oxide (Shenzhen Suiheng Technology Co., Ltd., CAS No.: 7782-45-5, hexagonal crystal system, structural formula as shown in Formula II) and 0.9 g of the liquid crystal polyester containing a hydrogen bond donor prepared in Example 1 in 20 g of tetrahydrofuran, stir (200 rpm) for 4 hours, ultrasonically disperse (480 W) for 4 hours, then dry the solvent at 60 °C and hot press at 160 °C for 10 min to obtain a high thermal conductivity liquid crystal polyester composite material.

[0049]

[0050] Characterize and test the prepared high thermal conductivity liquid crystal polyester composite material, and detect the thermal conductivity in each direction. The experimental data show that the thermal conductivity in the XY direction can reach 1.711 W m -1 K -1 , and the thermal conductivity in the Z direction can reach 0.624 W m -1 K -1 ; and use an infrared spectrometer to detect the material, and the experimental results are as Figure 1 shown.

[0051] Example 3

[0052] This example provides a high thermal conductivity liquid crystal polyester composite material and a preparation method thereof.

[0053] Dissolve 0.2 g of graphene oxide and 0.8 g of the liquid crystal polyester containing a hydrogen bond donor prepared in Example 1 in 20 g of tetrahydrofuran, stir for 4 hours, ultrasonically disperse for 4 hours, dry the solvent, and then hot press at 160 °C for 10 min to obtain a high thermal conductivity liquid crystal polyester composite material.

[0054] Characterize and test the prepared high thermal conductivity liquid crystal polyester composite material, and detect the thermal conductivity in each direction. The experimental data shows that the thermal conductivity in the XY direction can reach 1.351 W m -1 K -1 , and the thermal conductivity in the Z direction can reach 0.374 W m -1 K -1 ; and use an infrared spectrometer to detect the material, and the experimental results are as Figure 1 shown.

[0055] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A liquid crystal polyester containing a hydrogen bond donor, characterized in that The preparation method comprises the following steps: (1) Reacting a haloalcohol, biphenol and anhydrous potassium carbonate under reflux in a protective atmosphere. After cooling, water is added, followed by suction filtration, neutralization, washing with water and drying to obtain 4,4'-bis(6-hydroxyhexyloxy)biphenyl; (2) Mixing 4,4'-bis(6-hydroxyhexyloxy)biphenyl with 5-hydroxyisophthalic acid, adding a catalyst and heating for polycondensation reaction. Then, while carrying out suction filtration, continue heating the reaction to obtain a liquid crystal polyester containing a hydrogen bond donor; The molar ratio of the 4,4'-bis(6-hydroxyhexyloxy)biphenyl to 5-hydroxyisophthalic acid is 1-2:1-2.

2. The liquid crystal polyester containing a hydrogen bond donor according to claim 1, characterized in that: The haloalcohol is at least one of 2-bromoethanol, 3-chloro-1-propanol, 4-chlorobutanol or 6-chlorohexanol; The molar ratio of the haloalcohol to biphenol is 2-4:

1.

3. The liquid crystal polyester containing a hydrogen bond donor according to claim 1, characterized in that: The conditions for the heating polycondensation reaction are reacting at 150-200 °C for 2-4 h; The conditions for the continued heating reaction are reacting at 150-200 °C for 2-4 h.

4. The liquid crystal polyester containing a hydrogen bond donor according to claim 1, characterized in that: The catalyst is anhydrous zinc acetate and antimony trioxide; The mass of the anhydrous zinc acetate is 0.1-0.3% of the total mass of the reaction system; The mass of the antimony trioxide is 0.2-0.4% of the total mass of the reaction system.

5. The liquid crystal polyester containing a hydrogen bond donor according to claim 1, characterized in that: The protective atmosphere is a nitrogen atmosphere; The conditions for the reflux reaction are condensing and refluxing for 20-30 h; The cooling is to cool to room temperature; The conditions for the suction filtration are that the vacuum degree is lower than 30 Pa; The neutralization is to add hydrochloric acid to adjust the pH to 1; The conditions for the drying are drying at 70-90 °C for 20-30 h.

6. A preparation method of a high thermal conductivity liquid crystal polyester composite material, characterized in that It comprises the following steps: Dissolving graphene oxide and the liquid crystal polyester containing a hydrogen bond donor according to any one of claims 1-5 in tetrahydrofuran, stirring, ultrasonically dispersing, drying, and then obtaining a high thermal conductivity liquid crystal polyester composite material through hot pressing.

7. The preparation method according to claim 6, characterized in that: The CAS number of the graphene oxide is 7782-45-5; The stirring time is 3-5 h; The ultrasonic dispersion time is 3-5 h; The conditions for the hot pressing are hot pressing at 150-200 °C for 8-15 min.

8. A high thermal conductivity liquid crystal polyester composite material prepared by the preparation method according to any one of claims 6-7.

9. Use of the high thermal conductivity liquid crystal polyester composite material according to claim 8 in the preparation of electronic devices.

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