Polytetrafluoroethylene composite film as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of polytetrafluoroethylene composite materials, and particularly relates to a polytetrafluoroethylene composite film and a preparation method and application thereof. Aiming at the problem that polytetrafluoroethylene matrix resin is difficult to be compatible with inorganic heat-conducting filler boron nitride, trifluoromethyl substituted aryl glycidyl ether is designed and synthesized, the molecular structure of trifluoromethyl substituted aryl glycidyl ether comprises-CF3 and an epoxy group, and then trifluoromethyl substituted aryl glycidyl ether and amino silane coupling agent modified boron nitride are subjected to grafting reaction, so that-CF3 is introduced into the surface of boron nitride, and the surface of the boron nitride is modified. The compatibility with polytetrafluoroethylene is improved. The trifluoromethyl-grafted boron nitride and polytetrafluoroethylene composite film has better electrical insulating property, mechanical property and lower interface thermal resistance, is beneficial to reducing the heating phenomenon of a device, and provides clearer signal transmission.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polytetrafluoroethylene composites, and particularly relates to a trifluoromethyl-substituted aryl glycidyl ether, a polytetrafluoroethylene composite film and a preparation method and application thereof. BACKGROUND

[0002] With the continuous updating and rapid development of current microwave communication technology, high-frequency microwave substrates have been widely used in satellite navigation systems, 5G communication services and other fields, and there is an urgent need for polymer dielectric materials with better performance and stability for high-frequency microwave substrates. The requirements for polymer dielectric materials are high chemical corrosion resistance, strong hydrophobicity, excellent dielectric performance.

[0003] Among them, polytetrafluoroethylene (PTFE) is a multifunctional polymer material with excellent performance, which has good chemical inertness, outstanding dielectric properties, low hydrophilicity and hygroscopicity, and high thermal stability. In particular, PTFE has extremely low loss tangent (tan delta = 0.0003) and reliable dielectric constant (epsilon r = 2.1), and is widely used in high-frequency microwave composite substrates, but the low intrinsic thermal conductivity (lambda = 0.3 W / m K) of PTFE itself seriously limits the further application of PTFE in microwave composite substrates, especially in highly integrated components. This is because the low thermal conductivity of the material makes it difficult to transfer the heat generated by the increase in power of electronic components in time, thereby affecting the performance, service life and safety of electronic components, so a key problem to be solved is how to improve the thermal conductivity of PTFE polymer to meet the requirements.

[0004] The conventional technical solution is to add a thermally conductive filler to enhance the thermal conductivity of the PTFE matrix, but PTFE is a typical low-surface-energy material with very inert chemical properties, showing extremely strong hydrophobicity and oleophobicity. This means that it is difficult to produce physical or chemical adsorption with other substances. The existence of polar B-N bonds and the like on the surface of the thermally conductive filler such as boron nitride makes it have a certain hydrophilicity, and the surface energy is higher than that of PTFE. Therefore, the non-polar PTFE and the weak polarity of boron nitride cannot form strong chemical bonds, hydrogen bonds or dipole-dipole interactions between them, and can only rely on weak van der Waals forces, which cannot be uniformly dispersed, and boron nitride is easily aggregated in PTFE. Due to the loose combination between the PTFE matrix and the thermally conductive filler, there will be a large number of micro voids and defects at the interface between the two, and heat will be severely scattered when passing through such a loose interface, significantly increasing the interface thermal resistance, and further limiting the improvement of the overall thermal conductivity of the composite material. In addition, the weak interfacial bonding force between the PTFE matrix and the thermally conductive filler will lead to a decrease in the mechanical strength of the composite material, such as tensile strength and elongation at break, and the debonding of the filler and the matrix will become a stress concentration point, causing material failure. SUMMARY

[0005] In view of the defects of the prior art, the technical problem to be solved by the present application is to improve the compatibility of polytetrafluoroethylene matrix and boron nitride heat-conducting filler, reduce the interfacial thermal resistance of the two, and further improve the overall thermal conductivity, insulation performance and mechanical properties of the composite material. The specific scheme comprises providing a trifluoromethyl-substituted aryl glycidyl ether, a polytetrafluoroethylene composite film and a preparation method and application thereof. The trifluoromethyl-substituted aryl glycidyl ether is synthesized as a bridge for improving the polytetrafluoroethylene and boron nitride, the trifluoromethyl-substituted aryl glycidyl ether is grafted with the boron nitride treated by the amino silane coupling agent, and then the polytetrafluoroethylene is blended and processed to obtain the corresponding composite film.

[0006] To achieve the above technical purpose, the technical scheme adopted by the present application is as follows: In the first aspect, a trifluoromethyl-substituted aryl glycidyl ether has a general structure comprising , or ; Among them, Ar is selected from an aromatic group or a heteroaromatic group with 6 to 20 carbon atoms, 1-3-CF3 are connected to the Ar group, and at least one glycidyl ether group is contained in each molecule of the trifluoromethyl-substituted aryl glycidyl ether; Preferably, one glycidyl ether group is contained in each molecule of the trifluoromethyl-substituted aryl glycidyl ether; Preferably, Ar is selected from a phenyl group or a naphthyl group; More preferably, Ar is selected from a phenyl group; Preferably, the structure of the trifluoromethyl-substituted aryl glycidyl ether comprises one of , or .

[0007] In the second aspect, a preparation method of the above-mentioned trifluoromethyl-substituted aryl glycidyl ether comprises: reacting a trifluoromethyl-substituted aryl phenol as a raw material with epichlorohydrin to obtain the trifluoromethyl-substituted aryl glycidyl ether. Among them, the trifluoromethyl-substituted aryl phenol is any one of o-trifluoromethylphenol, m-trifluoromethylphenol, p-trifluoromethylphenol, 3,5-ditrifluoromethylphenol, 2,4,6-trifluorophenol, 8-(trifluoromethyl)-1-naphthol or 6-(trifluoromethyl)-1-naphthol; Preferably, the trifluoromethyl-substituted aryl phenol is any one of o-trifluoromethylphenol, m-trifluoromethylphenol, p-trifluoromethylphenol, 3,5-ditrifluoromethylphenol or 2,4,6-trifluorophenol.

[0008] Among them, the catalyst for the reaction of the trifluoromethyl-substituted aryl phenol with epichlorohydrin is a tetraalkylammonium halide.

[0009] Preferably, the quaternary ammonium halide is selected from any one of tetrabutylammonium bromide or tetrabutylammonium chloride.

[0010] Further, the specific steps for preparing the trifluoromethyl-substituted aryl glycidyl ether by reacting the trifluoromethyl-substituted aryl phenol with epichlorohydrin include: S1, reacting the trifluoromethyl-substituted aryl phenol as a raw material with epichlorohydrin using a quaternary ammonium halide as a phase transfer catalyst at 60-120℃, and removing the epichlorohydrin by distillation under reduced pressure after the reaction is completed; S2, adding an organic solvent and an aqueous sodium hydroxide solution to the residue of step S1, and continuing the reaction at 60-120℃; S3, after the reaction is completed, washing with saturated NaCl, taking the organic phase, and then distilling under reduced pressure, and finally drying the product under vacuum to obtain the trifluoromethyl-substituted aryl glycidyl ether.

[0011] In a third aspect, the trifluoromethyl-substituted aryl glycidyl ether described above is used in the preparation of a polytetrafluoroethylene-boron nitride composite material.

[0012] In a fourth aspect, a polytetrafluoroethylene composite film, the raw materials of which include: the trifluoromethyl-substituted aryl glycidyl ether described above, polytetrafluoroethylene, and amino silane coupling agent modified boron nitride.

[0013] The modification method of the amino silane coupling agent modified boron nitride includes: first crushing the boron nitride, treating it in an aqueous sodium hydroxide solution to obtain hydroxylated boron nitride, and then hydrolyzing the amino silane coupling agent and surface treating the hydroxylated boron nitride to obtain the amino silane coupling agent modified boron nitride.

[0014] The amino silane coupling agent is selected from one or a combination of more than one of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)methyldimethoxysilane, (3-aminopropyl)dimethylmethoxysilane, (3-aminopropyl)triethoxysilane, (3-aminopropyl)methyldiethoxysilane, (3-aminopropyl)dimethylethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, and N-β-aminoethyl-γ-aminopropylmethyldiethoxysilane. The polytetrafluoroethylene is selected from polytetrafluoroethylene powder or polytetrafluoroethylene aqueous dispersion.

[0015] Preferably, the polytetrafluoroethylene is selected from polytetrafluoroethylene aqueous dispersion.

[0016] More preferably, the solid content of the polytetrafluoroethylene aqueous dispersion is 40-80wt%.

[0017] Preferably, the boron nitride crystal form is hexagonal boron nitride (h-BN) or cubic boron nitride (c-BN).

[0018] Further, the ratio between the epoxy group mole amount of the trifluoromethyl-substituted aryl glycidyl ether and the active hydrogen mole amount of the amino silane coupling agent-modified boron nitride in the polytetrafluoroethylene composite film is (0.6-1):1.

[0019] Preferably, the ratio between the epoxy group mole amount of the trifluoromethyl-substituted aryl glycidyl ether and the active hydrogen mole amount of the amino silane coupling agent-modified boron nitride in the polytetrafluoroethylene composite film is (0.7-1):1.

[0020] The active hydrogen in the amino silane coupling agent-modified boron nitride is derived from the active hydrogen in -NH2 of the amino silane coupling agent.

[0021] Further, the raw material of the polytetrafluoroethylene composite film further comprises graphene.

[0022] Preferably, the graphene is flake graphene, the flake diameter of the graphene ranges from 0.5 to 5 μm, and the thickness of the graphene ranges from 0.8 to 1.2 nm.

[0023] In a fifth aspect, the above-mentioned method for preparing the polytetrafluoroethylene composite film comprises: grafting reaction of the amino silane coupling agent-modified boron nitride and the trifluoromethyl-substituted aryl glycidyl ether to obtain trifluoromethyl-grafted boron nitride, then blending and drying the trifluoromethyl-grafted boron nitride with polytetrafluoroethylene resin, and then placing the dried product in a mold for pressure heat treatment to obtain the polytetrafluoroethylene composite film.

[0024] Preferably, the mass ratio of the polytetrafluoroethylene resin to the trifluoromethyl-grafted boron nitride is 100:(20-40).

[0025] Preferably, the dried product is ground into powder in a high-speed grinder and placed in a mold for pressure heat treatment.

[0026] The step of pressure heat treatment comprises: under a pressure of 10-100 MPa, heating from room temperature to 240-320℃ at a rate of 90-110℃ / h and keeping the temperature for 10-90 min to obtain the polytetrafluoroethylene composite film.

[0027] Preferably, the step of pressure heat treatment comprises: under a pressure of 10-100 MPa, heating from room temperature to 250-300℃ at a rate of 90-110℃ / h and keeping the temperature for 30-60 min to obtain the polytetrafluoroethylene composite film.

[0028] Preferably, the drying is vacuum drying. Preferably, the temperature of the vacuum drying is 80-110 DEG C. Preferably, the conditions of the pressurized heat treatment include using a pressure of 10-50 MPa to press the polytetrafluoroethylene composite film.

[0029] Further, the method for preparing the polytetrafluoroethylene composite film includes blending the trifluoromethyl grafted boron nitride, graphene and polytetrafluoroethylene resin, drying, and placing the dried product in a mold to pressurize and press to obtain the polytetrafluoroethylene composite film.

[0030] Preferably, the mass ratio of the polytetrafluoroethylene resin, trifluoromethyl grafted boron nitride and graphene is 100:(20-40):(0.4-1.0).

[0031] Preferably, the mass ratio of the polytetrafluoroethylene resin, trifluoromethyl grafted boron nitride and graphene is 100:(20-40):(0.4-0.8).

[0032] In a sixth aspect, the polytetrafluoroethylene composite film described above is applied to the preparation of high-frequency copper-clad plates.

[0033] The present application has the advantages that: in view of the problem that polytetrafluoroethylene matrix resin and inorganic heat-conducting filler boron nitride are difficult to be compatible, trifluoromethyl substituted aryl glycidyl ether is designed and synthesized, the molecular structure of which contains -CF3 and epoxy groups, and then the boron nitride modified by the amino silane coupling agent is subjected to grafting reaction, thereby introducing -CF3 to the surface of the boron nitride and improving the compatibility with polytetrafluoroethylene. The composite film of trifluoromethyl grafted boron nitride and polytetrafluoroethylene has better electrical insulation, mechanical properties and lower interfacial thermal resistance, which is conducive to reducing the heating phenomenon of the device and providing clearer signal transmission. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, more completely understand the present application and its advantages, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating any creative labor on the basis of these drawings.

[0035] Figure 1 The F-NMR spectrum of the p-trifluoromethyl phenyl glycidyl ether synthesized for Example 1 1 H-NMR nuclear magnetic hydrogen spectrum, wherein a, b, c and d correspond to hydrogen atoms in different environments.

[0036] Figure 2 The F-NMR spectrum of the p-trifluoromethyl phenyl glycidyl ether synthesized for Example 1 19 F-NMR nuclear magnetic fluorine spectrum. DETAILED DESCRIPTION

[0037] The application is further described in connection with the following specific examples. It should be understood that these examples are intended to illustrate the application and are not intended to limit the scope of the application. Furthermore, since numerous modifications and changes will occur to those skilled in the art, these are intended to be within the scope of the application as defined by the appended claims.

[0038] It should be noted that the terms used herein are for the purpose of describing specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof.

[0039] All documents mentioned in this application are incorporated by reference as if each document were individually incorporated by reference. Unless and to the extent that the contrary is clear from their contexts, reference herein to cited documents is not intended as a representation that any or each cited document is prior art. The citation of any document is not an admission that it is prior art. All citations relied upon are expressly incorporated by reference, in their entireties, for all purposes. The definitions of the terms, phrases, and nomenclature used in the cited documents are also incorporated by reference. Examples and preferred ways of implementing the cited documents are also incorporated by reference. However, the citation of a document is not to be interpreted as an admission that it is prior art to the application described and / or claimed herein. To the extent that any meaning or definition of a term in this document conflicts with the meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to the term in this document shall govern.

[0040] If the specific conditions of the experiment are not specified in the examples, the general conditions of the art are usually followed, or the conditions recommended by the reagent company are followed; the materials, reagents, etc. used in the examples can be purchased through commercial channels, unless otherwise specified.

[0041] Example 1 p-Trifluoromethylphenol 64.8 g (0.4 mol), 192 mL of epichlorohydrin and 8.5 g of catalyst tetrabutylammonium bromide were added into a three-necked flask, and the reaction was carried out at 90°C for 6 hours under stirring. After the reaction was completed, the reaction mixture was cooled to room temperature, and excess epichlorohydrin was removed by distillation under reduced pressure.

[0042] To the above residue, 192 mL of toluene and 85 g of 30 wt% sodium hydroxide solution (prepared using 25.5 g of NaOH) were added, and the mixture was warmed to 90°C for 3 hours under stirring. After the reaction was completed, the mixture was washed with saturated NaCl three times, and the organic phase was distilled under reduced pressure. The final product, a yellow liquid, was dried at 60°C under vacuum for 12 hours to obtain 75.0 g of p-trifluoromethylphenyl glycidyl ether with a yield of 86.0%. The proton nuclear magnetic resonance spectrum of the p-trifluoromethylphenyl glycidyl ether synthesized in Example 1 is shown in Figure 1 Figure 2

[0043]

[0044] Example 2 To a three-necked flask, 3,5-bistrifluoromethylphenol 92.0 g (0.4 mol), 192 mL of epichlorohydrin, and 8.5 g of catalyst tetrabutylammonium bromide were added, and the mixture was warmed to 90°C for 8 hours under stirring. After the reaction was completed, the mixture was cooled to room temperature, and excess epichlorohydrin was removed by distillation under reduced pressure.

[0045] To the above residue, 192 mL of toluene and 85 g of 30 wt% sodium hydroxide solution (prepared using 25.5 g of NaOH) were added, and the mixture was warmed to 90°C for 4 hours under stirring. After the reaction was completed, the mixture was washed with saturated NaCl three times, and the organic phase was distilled under reduced pressure. The final product, a yellow liquid, was dried at 60°C under vacuum for 12 hours to obtain 91.4 g of 3,5-bistrifluoromethylphenyl glycidyl ether with a yield of 79.8%.

[0046]

[0047] Example 3 To 500 g of hexagonal boron nitride particles, a knife-type pulverizer was used to pulverize the boron nitride to 600 mesh, and a jet-type airflow mill was used to perform superfine pulverization to 1000 mesh. Subsequently, the boron nitride was placed in a 5 mol / L aqueous sodium hydroxide solution, and was treated at 120°C for 24 hours. Subsequently, the boron nitride was filtered and classified, and was repeatedly washed with deionized water until the filtrate was neutral. The thus-obtained hydroxylated boron nitride was dried at 60°C under vacuum for 24 hours and was used as is.

[0048] Example 4 To 3 g of (3-aminopropyl)methyldiethoxysilane and 5 g of (3-aminopropyl)dimethylethoxysilane as hydrolysable silane coupling agents, 27 g of ethanol and 5 g of deionized water were added, and the mixture was warmed to 80°C to reflux for 2 hours. Subsequently, 100 g of the hydroxylated boron nitride prepared in Example 3 was added, and the mixture was continuously stirred at 80°C for 12 hours. After the reaction was completed, the mixture was filtered, and the product was dried at 60°C under vacuum to obtain silane-modified boron nitride. ​​

[0049] Example 5 Example 5

[0050] Example 6 Example 6

[0051] Example 7 Example 7

[0052] Example 7

[0053] Example 8 Example 8

[0054] Example 9 To a high-speed mixing coater, 100 g of the silane-modified boron nitride prepared in Example 5 was added, and a grafting reaction was performed with 16 g of the p-trifluoromethylphenyl glycidyl ether prepared in Example 1, and the remaining steps were the same as in Example 7, whereby a polytetrafluoroethylene composite film was prepared.

[0055] Example 10 To a high-speed mixing coater, 100 g of the silane-modified boron nitride prepared in Example 5 was added, and a grafting reaction was performed with 22 g of the 3,5-bistrifluoromethylphenyl glycidyl ether prepared in Example 2, and the remaining steps were the same as in Example 7, whereby a polytetrafluoroethylene composite film was prepared.

[0056] Example 11 To a high-speed mixing coater, 100 g of the silane-modified boron nitride prepared in Example 5 was added, and a grafting reaction was performed with 16 g of the p-trifluoromethylphenyl glycidyl ether prepared in Example 1, and the remaining steps were the same as in Example 7, whereby a polytetrafluoroethylene composite film was prepared.

[0057] Example 12 To a high-speed mixing coater, 100 g of the silane-modified boron nitride prepared in Example 5 was added, and a grafting reaction was performed with 22 g of the 3,5-bistrifluoromethylphenyl glycidyl ether prepared in Example 2, and the remaining steps were the same as in Example 7, whereby a polytetrafluoroethylene composite film was prepared.

[0058] Example 13 To a high-speed mixing coater, 100 g of the silane-modified boron nitride prepared in Example 5 was added, and a grafting reaction was performed with 16 g of the p-trifluoromethylphenyl glycidyl ether prepared in Example 1, and the remaining steps were the same as in Example 7, whereby a polytetrafluoroethylene composite film was prepared.

[0059] Example 14 To a high-speed mixing coater, 100 g of the silane-modified boron nitride prepared in Example 5 was added, and a grafting reaction was performed with 16 g of the p-trifluoromethylphenyl glycidyl ether prepared in Example 1, and the remaining steps were the same as in Example 7, whereby a polytetrafluoroethylene composite film was prepared.

[0060] Example 15 To a high-speed mixing coater, 100 g of the silanized boron nitride prepared in Example 6 was added, and 18 g of the p-trifluoromethyl phenyl glycidyl ether prepared in Example 1 was added to perform a grafting reaction, in which the mass ratio of the trifluoromethyl grafted boron nitride, PTFE, and flaky graphene was 30:100:0.5, and the remaining steps were the same as in Example 11, thereby preparing a polytetrafluoroethylene composite film.

[0061] Example 16 To a high-speed mixing coater, 100 g of the silanized boron nitride prepared in Example 6 was added, and 24 g of the 3,5-bistrifluoromethyl phenyl glycidyl ether prepared in Example 2 was added to perform a grafting reaction, in which the mass ratio of the trifluoromethyl grafted boron nitride, PTFE, and flaky graphene was 30:100:0.5, and the remaining steps were the same as in Example 11, thereby preparing a polytetrafluoroethylene composite film.

[0062] Comparative Example 1 To a high-speed mixing coater, 100 g of the hydroxylated boron nitride prepared in Example 3 was added, and 15 g of the p-trifluoromethyl phenyl glycidyl ether prepared in Example 1 was added to perform a grafting reaction, and the remaining steps were the same as in Example 7, thereby preparing a polytetrafluoroethylene composite film.

[0063] Comparative Example 2 Without using the trifluoromethyl-substituted aryl glycidyl ether prepared in Examples 1-2, the silanized boron nitride prepared in Example 4 was directly mixed with a PTFE aqueous dispersion (PTFE solid content: 60 wt%), and the subsequent steps were the same as in Example 7, in which the mass ratio of the silanized boron nitride and PTFE was 30:100.

[0064] The tensile strength of the polytetrafluoroethylene composite films prepared in Examples 7-16 and Comparative Examples 1-2 was tested using a universal testing machine (RWT 10), in which the loading rate was 5 mm / min.

[0065] The dielectric constant and dielectric loss of the polytetrafluoroethylene composite films prepared in Examples 7-16 and Comparative Examples 1-2 were tested at a frequency of 10 GHz (X-band) using a vector network analyzer, with reference to the method for testing the dielectric constant of a strip line in X-band according to 2.5.5.5 of the IPC-TM-650 test standard.

[0066] The thermal conductivity of the polytetrafluoroethylene composite films prepared in Examples 7-16 and Comparative Examples 1-2 was tested with reference to the standard of DIN 52612.

[0067] The above test results are listed in Table 1.

[0068] Table 1

[0069] From the test results of Table 1, it can be seen that the polytetrafluoroethylene composite films obtained by processing the polytetrafluoroethylene resin matrix with the boron nitride modified by the amino silane coupling agent and the trifluoromethyl-substituted aryl glycidyl ether of Examples 7-16 have better compatibility, better mechanical properties and lower interfacial thermal resistance, and thus can improve the overall efficiency, reduce the heating phenomenon, and provide clearer signal transmission, reduce signal attenuation and distortion, and are more suitable for application in high-frequency microwave communication technology. The amino silane coupling agent serves as an important bridging component and provides reactivity with the trifluoromethyl-substituted aryl glycidyl ether.

[0070] In addition, Examples 11-12 and Examples 15-16 also add graphene sheets, which are structures composed of carbon atoms in sp2 hybridization and have high electron mobility. The addition of graphene to the composite material can improve the electrical conductivity and thermal conductivity to some extent and is suitable for applications that require thermal conductivity but do not require high insulation.

[0071] Comparative Example 1 does not modify the boron nitride with a silane, and the boron nitride has poor compatibility with the polytetrafluoroethylene matrix. Moreover, the trifluoromethylphenyl glycidyl ether lacks corresponding reaction sites after being added, and thus cannot increase the compatibility between the boron nitride and the polytetrafluoroethylene. Therefore, there is a higher interfacial thermal resistance between the boron nitride and the polytetrafluoroethylene, and the mechanical properties and thermal conductivity are not ideal.

[0072] Comparative Example 2 does not use a trifluoromethyl-substituted aryl glycidyl ether as a bridge to further connect the boron nitride and the polytetrafluoroethylene matrix. The compatibility between the boron nitride and the polytetrafluoroethylene is low, and the corresponding mechanical properties and thermal conductivity are relatively lower than those of Examples 7-16.

[0073] The above-described examples only express several embodiments of the present application, facilitate specific and detailed understanding of the technical solutions of the present application, but should not be understood as limiting the scope of patent protection. It should be noted that, for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. In addition, it should be understood that, after reading the above description of the present application, those skilled in the art can make various modifications or improvements to the present application, and the equivalent forms obtained are also within the scope of protection of the present application. It should also be understood that, based on the technical solutions provided by the present application, those skilled in the art can obtain technical solutions through logical analysis, reasoning or limited experiments, which are within the scope of protection of the appended claims of the present application. Therefore, the scope of protection of the patent of the present application should be based on the contents of the appended claims, and the description can be used to explain the contents of the claims.

Claims

1. A trifluoromethyl-substituted aryl glycidyl ether, characterized in that, The general structural formula includes , or ; Wherein, the Ar is selected from aryl or heteroaryl groups with 6 to 20 carbon atoms, and 1 to 3 -CF3 groups are attached to the Ar group, and each molecule of trifluoromethyl substituted aryl glycidyl ether contains at least one glycidyl ether group.

2. A method for preparing the trifluoromethyl-substituted aryl glycidyl ether as described in claim 1, comprising: The product is obtained by reacting trifluoromethyl-substituted arylphenols with epichlorohydrin. The trifluoromethyl substituted arylphenol is any one of the following: o-trifluoromethylphenol, m-trifluoromethylphenol, p-trifluoromethylphenol, 3,5-ditrifluoromethylphenol, 2,4,6-trifluorophenol, 8-(trifluoromethyl)-1-naphthol, or 6-(trifluoromethyl)-1-naphthol; The catalyst for the reaction of the trifluoromethyl substituted arylphenol with epichlorohydrin is a tetraalkyl ammonium halide.

3. The method for preparing the trifluoromethyl-substituted aryl glycidyl ether according to claim 2, characterized in that, The specific steps of the preparation method include: S1, trifluoromethyl substituted arylphenols were used as raw materials to react with epichlorohydrin, using tetraalkylammonium halide as a phase transfer catalyst, and the reaction was carried out at 60-120℃. After the reaction was completed, epichlorohydrin was removed by vacuum distillation. S2. Add an organic solvent and an aqueous sodium hydroxide solution to the residue from step S1, and continue the reaction at 60-120°C. S3. After the reaction is complete, wash with saturated NaCl, take the organic phase and then distill under reduced pressure. The final product is dried under vacuum to obtain trifluoromethyl substituted aryl glycidyl ether.

4. An application characterized in that, The application of the trifluoromethyl substituted aryl glycidyl ether as described in claim 1 in the preparation of polytetrafluoroethylene-boron nitride composite materials.

5. A polytetrafluoroethylene composite film, characterized in that, The raw materials for the polytetrafluoroethylene composite film include: the trifluoromethyl substituted aryl glycidyl ether as described in claim 1, polytetrafluoroethylene, and boron nitride modified with an aminosilane coupling agent; The modification method of boron nitride modified by aminosilane coupling agent includes: first, crushing boron nitride and treating it in sodium hydroxide aqueous solution to obtain hydroxylated boron nitride; then, hydrolyzing the aminosilane coupling agent and then surface treating the hydroxylated boron nitride to obtain boron nitride modified by aminosilane coupling agent. The aminosilane coupling agent is selected from one or more combinations of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)methyldimethoxysilane, (3-aminopropyl)dimethylmethoxysilane, (3-aminopropyl)triethoxysilane, (3-aminopropyl)methyldiethoxysilane, (3-aminopropyl)dimethylethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, and N-β-aminoethyl-γ-aminopropylmethyldiethoxysilane. The polytetrafluoroethylene is selected from polytetrafluoroethylene powder or polytetrafluoroethylene aqueous dispersion.

6. The polytetrafluoroethylene composite film according to claim 5, characterized in that, The ratio between the molar amount of epoxy groups of trifluoromethyl substituted aryl glycidyl ether and the molar amount of active hydrogens of boron nitride modified with aminosilane coupling agent in polytetrafluoroethylene composite films is (0.6-1):

1.

7. The polytetrafluoroethylene composite film according to claim 5, characterized in that, The raw materials for the polytetrafluoroethylene composite film also include graphene.

8. A method for preparing a polytetrafluoroethylene composite film as described in any one of claims 5-7, characterized in that, The preparation method includes: grafting boron nitride modified with aminosilane coupling agent with trifluoromethyl substituted aryl glycidyl ether to obtain boron nitride grafted with trifluoromethyl, then blending it with polytetrafluoroethylene resin and drying it, and placing the dried product in a mold and pressing it to obtain a polytetrafluoroethylene composite film. The mass ratio of the polytetrafluoroethylene resin to the boron nitride grafted with trifluoromethyl is 100:(20-40). The pressurized heat treatment step includes: heating from room temperature to 240-320℃ at a rate of 90-110℃ / h under a pressure of 10-100MPa and holding at this temperature for 10-90min to obtain a polytetrafluoroethylene composite film.

9. The method for preparing the polytetrafluoroethylene composite film according to claim 8, characterized in that, The preparation method of polytetrafluoroethylene composite film includes blending and drying boron nitride grafted with trifluoromethyl, graphene and polytetrafluoroethylene resin, and pressing the dried product in a mold to obtain polytetrafluoroethylene composite film. The mass ratio of the polytetrafluoroethylene resin, the boron nitride grafted with trifluoromethyl to the graphene is 100:(20-40):(0.4-1.0).

10. An application characterized in that, The application of the polytetrafluoroethylene composite film as described in any one of claims 5-7 in the preparation of high-frequency copper-clad laminates.

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