Preparation method of high-dielectric high-conductivity epoxy resin
By using molecular structure design and nanocomposite technology, and employing processes such as gradient curing and ultrasonic dispersion, high dielectric and high conductivity epoxy resins were prepared. This solved the problem of the difficulty in synergistically improving the dielectric and conductivity properties of traditional epoxy resins, and achieved optimization of material properties and improvement of production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional epoxy resins have low dielectric constants and poor conductivity, making it difficult to meet the needs of scenarios such as 5G communication and new energy vehicles. Furthermore, the poor compatibility between inorganic fillers and epoxy resin matrices leads to a decline in the mechanical properties of the material and an increase in dielectric loss. The process is complex, with low production efficiency and high cost.
Through molecular structure design, nanocomposite technology and process optimization, bisphenol A type epoxy resin is copolymerized with polytetrafluoroethylene, surface-modified barium titanate-carbon nanotube composite filler is added, and gradient curing and ultrasonic dispersion technology are combined with annealing and plasma treatment to form a high dielectric and high conductivity epoxy resin.
With a dielectric constant of over 8, reduced dielectric loss, increased conductivity by 8 orders of magnitude, excellent mechanical properties, and increased production efficiency by over 30%, it is suitable for flexible electronic devices and electromagnetic shielding materials.
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing a high-dielectric-high-conductivity epoxy resin. Background Technology
[0002] Traditional epoxy resins are widely used in electronic packaging, circuit boards, and other fields due to their excellent mechanical properties, chemical stability, and processing characteristics. However, their dielectric constant (ε) is typically below 4.0, and their conductivity is extremely low (resistivity > 10). 14 The dielectric constant (Ω·cm) is insufficient to meet the demands of high-dielectric and high-conductivity materials in applications such as 5G communication and new energy vehicles. Existing technologies can improve dielectric constant or conductivity by adding inorganic fillers (such as barium titanate and carbon nanotubes), but these methods have the following drawbacks: Performance imbalance: The addition of a single filler can lead to the inability to optimize the dielectric and electrical properties of the material in a coordinated manner. For example, although carbon nanotubes can improve conductivity, they will reduce dielectric constant.
[0003] Poor interfacial compatibility: The weak interfacial bonding between inorganic fillers and epoxy resin matrix can easily lead to a decrease in the mechanical properties of the material and an increase in dielectric loss.
[0004] Complex process: Multi-component compounding requires multiple mixing and curing processes, resulting in low production efficiency and high cost. Summary of the Invention
[0005] To overcome the problem of difficulty in synergistically improving the dielectric and conductivity properties of epoxy resin materials in existing technologies, this invention provides a method for preparing high-dielectric-high-conductivity epoxy resin. Through molecular structure design, nanocomposite technology and process optimization, this invention achieves a synergistic improvement in the dielectric constant and conductivity of epoxy resin, while maintaining the material's mechanical properties and processing stability.
[0006] To achieve the above objectives, the present invention provides a method for preparing a high-dielectric-high-conductivity epoxy resin, the method comprising the following steps: (1) Copolymerize bisphenol A type epoxy resin with polytetrafluoroethylene at 80-100℃ for 2-3 hours; (2) Add aromatic amines to the reaction product obtained in step (1) to carry out the reaction; (3) Add surface-modified barium titanate-carbon nanotube composite filler to the product obtained in step (2), and cure by ultrasonication and gradient heating, and then cast into shape. (4) Anneal the product obtained in step (3); (5) The product obtained in step (4) is subjected to plasma treatment.
[0007] Preferably, the weight ratio of the bisphenol A type epoxy resin, the polytetrafluoroethylene, the aromatic amine, and the surface-modified barium titanate-carbon nanotube composite filler is 100:6-10:4-6:8-12.
[0008] Preferably, the epoxy equivalent of the bisphenol A type epoxy resin is 180-220 g / eq.
[0009] Preferably, the fluorine content of the polytetrafluoroethylene is 30-50 wt%.
[0010] Preferably, the aromatic amine is selected from at least one of m-phenylenediamine, p-phenylenediamine, and o-phenylenediamine.
[0011] Preferably, in step (2), the reaction conditions include: a temperature of 100-120°C and a time of 1-2 hours.
[0012] Preferably, the surface modifier for surface modification of the barium titanate-carbon nanotube composite filler is a silane coupling agent.
[0013] Preferably, in the barium titanate-carbon nanotube composite filler, the mass ratio of barium titanate to carbon nanotubes is 1.5-4:1.
[0014] Preferably, the preparation process of the barium titanate-carbon nanotube composite filler includes: ultrasonically treating carbon nanotubes in a mixed solution of concentrated hydrochloric acid and concentrated sulfuric acid for 30 minutes, then refluxing at 65°C for 4 hours, and then washing and drying to obtain hydroxylated carbon nanotubes; then mixing Ba(OH)2 aqueous solution containing TiO2 particles with hydroxylated carbon nanotubes and carrying out a hydrothermal reaction at 380-450°C and 30-50 MPa for 8-24 hours to crystallize barium titanate on the surface of carbon nanotubes, and then filtering, washing and drying after cooling to obtain the composite filler.
[0015] Preferably, the silane coupling agent is at least one of KH-550, KH-560 and KH-570.
[0016] Preferably, the amount of the surface modifier is 5-15% by weight of the barium titanate-carbon nanotube composite filler.
[0017] Preferably, in step (3), the conditions for ultrasound include: power of 250-350W and time of 25-35 minutes.
[0018] Preferably, in step (3), the gradient temperature curing process includes: first pre-curing at 80-90℃ for 1-2 hours; then heating to 140℃ for 2-3 hours.
[0019] Preferably, in step (3), after casting, the mixture is left to stand for 15-40 hours at 15-40℃ and 40-70% relative humidity.
[0020] Preferably, in step (4), the annealing conditions include: a temperature of 70-80°C and a time of 2-3 hours.
[0021] Preferably, in step (5), the conditions for plasma treatment include: power of 60-100W and time of 5-7 minutes.
[0022] Compared with the prior art, the present invention has at least the following advantages: (1) Molecular structure design: Fluorine monomer modification: Polytetrafluoroethylene is introduced into bisphenol A epoxy resin to enhance molecular polarizability and improve dielectric constant by utilizing the high electronegativity of fluorine atoms.
[0023] By reacting glycidyl ether in bisphenol A epoxy resin with aromatic amines, a conjugated structure is introduced into the epoxy resin molecular chain, forming an electronic conduction channel and improving conductivity. (2) Nanocomposite technology: Bifunctional filler selection: Surface-modified barium titanate-carbon nanotube composite filler is adopted, in which barium titanate improves the dielectric constant and carbon nanotubes form a conductive network to achieve synergistic performance.
[0024] Interface optimization: The filler is surface-treated with a surface modifier to enhance the interfacial bonding force with the epoxy resin matrix and reduce interfacial defects.
[0025] (3) Process optimization: Gradient curing process: The gradient temperature rise strategy of "low temperature pre-curing - high temperature main curing" is adopted to reduce the internal stress of the material and avoid filler agglomeration.
[0026] Ultrasonic dispersion technology: Ultrasonic dispersion is used during the filler addition stage to ensure uniform distribution of fillers and improve the stability of material performance.
[0027] (4) Post-processing: Annealing: Annealing eliminates internal stress in materials and improves the stability of dielectric properties. Surface treatment: Plasma treatment is applied to the cured material to enhance surface conductivity, making it suitable for flexible electronic devices.
[0028] (5) Results data: Dielectric properties: The dielectric constant (ε) is increased to over 8 (test frequency 1MHz), which is more than 100% higher than that of traditional epoxy resin; the dielectric loss tangent (tanδ) is less than 0.04, meeting the requirements of high-frequency applications.
[0029] Electrical conductivity: Volume resistivity reduced to 10 4 -10 6The Ω·cm is 8 orders of magnitude lower than that of traditional epoxy resins, making it suitable for electromagnetic shielding materials.
[0030] Mechanical properties: tensile strength ≥80MPa, elongation at break ≥6%, possessing both high dielectric strength, high electrical conductivity and good toughness.
[0031] Process feasibility: By using gradient curing and ultrasonic dispersion technology, uniform dispersion of fillers and interface optimization can be achieved, increasing production efficiency by more than 30%. Detailed Implementation
[0032] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.
[0033] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0034] The method for preparing high-dielectric and high-conductivity epoxy resin provided by the present invention includes the following steps: (1) Copolymerize bisphenol A type epoxy resin with polytetrafluoroethylene at 80-100℃ for 2-3 hours; (2) Add aromatic amines to the reaction product obtained in step (1) to carry out the reaction; (3) Add surface-modified barium titanate-carbon nanotube composite filler to the product obtained in step (2), and cure by ultrasonication and gradient heating, and then cast into shape. (4) Anneal the product obtained in step (3); (5) The product obtained in step (4) is subjected to plasma treatment.
[0035] This invention utilizes specific steps to sequentially add aromatic amines and barium titanate-carbon nanotube composite fillers to bisphenol A epoxy resin for reaction, and employs specific curing procedures and post-treatment to obtain a high-dielectric-high-conductivity epoxy resin.
[0036] In some preferred embodiments, the weight ratio of the bisphenol A epoxy resin, the polytetrafluoroethylene, the aromatic amine, and the surface-modified barium titanate-carbon nanotube composite filler can be 100:6-10:4-6:8-12.
[0037] In step (1), bisphenol A type epoxy resin and polytetrafluoroethylene are copolymerized. Polytetrafluoroethylene is introduced into the bisphenol A type epoxy resin. The high electronegativity of fluorine atoms enhances the molecular polarizability, which can improve the dielectric constant of the epoxy resin.
[0038] In some embodiments, the epoxy equivalent of the bisphenol A type epoxy resin can be 180-220 g / eq.
[0039] In some embodiments, the fluorine content of the polytetrafluoroethylene can be 30-50 wt%, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%. Preferably, the amount of fluorinated monomer polytetrafluoroethylene added can be controlled at 6-10 wt% of the bisphenol A epoxy resin, for example, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%, to improve the dielectric constant of the epoxy resin.
[0040] In step (2), an aromatic amine is added to the reaction product obtained in step (1) to carry out the reaction. The glycidyl ether in the bisphenol A epoxy resin reacts with the aromatic amine to introduce a conjugated structure into the epoxy resin molecular chain, forming an electronic conduction channel, which can improve the conductivity of the epoxy resin.
[0041] In some embodiments, the aromatic amine is selected from at least one of m-phenylenediamine, p-phenylenediamine, and o-phenylenediamine.
[0042] In some preferred embodiments, in step (2), the temperature of the reaction can be 100-120°C, for example 100°C, 105°C, 110°C, 115°C or 120°C; and the time can be 1-2 hours, for example 1 hour, 1.5 hours or 2 hours.
[0043] In step (3), a surface-modified barium titanate-carbon nanotube composite filler is added to the product obtained in step (2). The filler is surface-treated by a surface modifier to enhance the interfacial bonding force with the epoxy resin matrix and reduce interfacial defects. The surface-modified barium titanate-carbon nanotube composite filler is used, in which barium titanate increases the dielectric constant and carbon nanotubes form a conductive network to achieve synergistic performance.
[0044] In one embodiment, the preparation process of the barium titanate-carbon nanotube composite filler includes: ultrasonically treating carbon nanotubes in a mixed solution of concentrated hydrochloric acid and concentrated sulfuric acid for 30 minutes, then refluxing at 65°C for 4 hours, followed by washing and drying to obtain hydroxylated carbon nanotubes; then mixing the hydroxylated carbon nanotubes with an aqueous solution of Ba(OH)₂ containing TiO₂ particles and subjecting them to a hydrothermal reaction at 380-450°C and 30-50 MPa for 8-24 hours to allow barium titanate to crystallize on the surface of the carbon nanotubes; after cooling, filtering, washing, and drying to obtain the composite filler. Further, in the obtained barium titanate-carbon nanotube composite filler, the mass ratio of barium titanate to carbon nanotubes is 1.5-4:1.
[0045] In a more specific embodiment, the preparation process of the barium titanate-carbon nanotube composite filler includes: 1) Carbon nanotubes were ultrasonically treated in a mixed solution of concentrated hydrochloric acid and concentrated sulfuric acid for 30 minutes. The volume ratio of concentrated hydrochloric acid (37wt%) to concentrated sulfuric acid (98wt%) was 3:1. Then, the solution was refluxed at 65°C for 4 hours to form oxygen-containing functional groups on the surface. After washing and drying, hydroxylated carbon nanotubes were obtained. 2) The aqueous solution of Ba(OH)2 containing TiO2 particles is mixed with hydroxylated carbon nanotubes and subjected to a hydrothermal reaction at 380-450℃ and 30-50MPa for 8-24 hours to allow barium titanate to crystallize on the surface of carbon nanotubes. The molar ratio of TiO2 particles to Ba(OH)2 is 1:1. After cooling, the mixture is filtered, washed, and dried to obtain the composite filler.
[0046] In some embodiments, the particle size of the barium titanate-carbon nanotube composite filler can be 50-150 nm.
[0047] In other embodiments, the specific surface area of the barium titanate-carbon nanotube composite filler can be 10-20 m². 2 / g.
[0048] In a preferred embodiment, to enhance the interfacial bonding force with the epoxy resin matrix and reduce interfacial defects, the surface modifier for surface modification of the barium titanate-carbon nanotube composite filler is a silane coupling agent.
[0049] In this invention, the silane coupling agent can be a conventionally selected one in the art. In some embodiments, the silane coupling agent is at least one of KH-550, KH-560, and KH-570; In some preferred embodiments, the amount of the surface modifier is 5-15% by weight of the barium titanate-carbon nanotube composite filler, for example, it can be 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight or 15% by weight.
[0050] In this invention, the method of using silane coupling agents to modify the surface of barium titanate-carbon nanotube composite fillers is not limited and can be a conventional operation in the field.
[0051] In one embodiment, the method for surface modification of barium titanate-carbon nanotube composite filler using a silane coupling agent includes: calcining the barium titanate-carbon nanotube composite filler at 500°C to remove surface organic matter, then soaking it in 2 mol / L NaOH solution to remove the coating layer, washing it until neutral, and drying it; mixing the silane coupling agent solution with the barium titanate-carbon nanotube composite filler, ultrasonically vibrating it for 10 hours to promote the reaction, centrifuging to separate the unreacted coupling agent, washing it three times with acetone and n-hexane, and vacuum drying it at 60°C for 10 hours to obtain the modified product.
[0052] In this invention, ultrasonic dispersion is used during the filler addition stage to ensure uniform distribution of the filler and improve the stability of material performance. In some embodiments, the ultrasonic conditions in step (3) include: power of 250-350W and time of 25-35 minutes.
[0053] In this invention, after casting, the material thickness is controlled at 0.5-2mm. Further, in step (3), after casting, the material is left to stand for 15-40 hours at 15-40℃ and 40-70% relative humidity.
[0054] In this invention, the gradient curing process adopts a gradient temperature rise strategy of "low temperature pre-curing - high temperature main curing", which can avoid uneven material properties caused by local overheating, reduce internal stress of the material, and avoid filler agglomeration. In a preferred embodiment, in step (3), the curing is a gradient temperature rise curing process: first, pre-curing at 80-90℃ for 1-2 hours; then raising the temperature to 140℃ for 2-3 hours.
[0055] In this invention, annealing eliminates internal stress in the material, thereby improving the stability of dielectric properties. Specifically, the annealing process is carried out under an inert atmosphere to prevent oxidation from affecting the dielectric properties. In some embodiments, the annealing conditions in step (4) include: a temperature of 70-80°C and a time of 2-3 hours.
[0056] In this invention, plasma treatment of the cured material enhances its surface conductivity, making the epoxy resin suitable for flexible electronic devices. In some embodiments, step (5) includes plasma treatment conditions of 60-100W power and 5-7 minutes.
[0057] An epoxy resin possessing both high dielectric constant and high conductivity can be prepared using the method described in this invention. This epoxy resin is suitable for applications such as flexible electronic devices, electromagnetic shielding materials, and high-frequency circuit boards, and can solve the technical challenge of synergistically improving the dielectric and conductivity properties of traditional epoxy resins.
[0058] In this invention, the parallel-plate capacitor method is used to test the dielectric constant and dielectric loss of epoxy resin. The testing principle is as follows: the parallel-plate capacitor method calculates the relative dielectric constant by measuring the capacitance without a dielectric (vacuum / air) and the capacitance after inserting an epoxy resin sample. The dielectric loss tangent is indirectly calculated by the phase difference between the current and voltage under AC voltage. The experimental steps include: 1. Sample preparation: Process the epoxy resin into a thin sheet of uniform thickness (usually 0.1-2 mm), ensuring a smooth surface. 2. Instrument zeroing: Zero the instrument using an LCR meter or dielectric constant meter when there is no sample between the parallel-plate electrodes. 3. Capacitance measurement: Measure the capacitance without a dielectric. Insert the resin sample and measure the capacitance. Data recording: Repeat the measurement 6 times, recording parameters such as thickness and electrode diameter. The test frequency is 1 MHz. 4. Calculate the dielectric constant and dielectric loss.
[0059] In this invention, the tensile strength and elongation at break of epoxy resin are determined in accordance with GB / T 1040 "Determination of tensile properties of plastics".
[0060] In this invention, the volume resistivity ρ of epoxy resin is determined using a three-electrode method. The specific process includes: placing a protective electrode on each side of the sample, and a measuring electrode in the middle; measuring the potential difference and then calculating the resistivity. The formula for calculating the volume resistivity ρ is: ρ = R × A / L, where R is the material resistance (Ω), and A is the sample cross-sectional area (m²). 2 L is the sample length (m).
[0061] The following examples further illustrate the preparation method of the high-dielectric and high-conductivity epoxy resin according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.
[0062] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.
[0063] In the following embodiments: The preparation process of the barium titanate-carbon nanotube composite filler includes: 1) Carbon nanotubes were ultrasonically treated in a mixed solution of concentrated hydrochloric acid and concentrated sulfuric acid for 30 minutes. The volume ratio of concentrated hydrochloric acid (37wt%) to concentrated sulfuric acid (98wt%) was 3:1. Then, the solution was refluxed at 65°C for 4 hours to form oxygen-containing functional groups on the surface. After washing and drying, hydroxylated carbon nanotubes were obtained. 2) The aqueous solution of Ba(OH)2 containing TiO2 particles was mixed with hydroxylated carbon nanotubes and subjected to a hydrothermal reaction at 400℃ and 40MPa for 12 hours to allow barium titanate to crystallize on the surface of the carbon nanotubes. The molar ratio of TiO2 particles to Ba(OH)2 was 1:1. After cooling, the mixture was filtered, washed, and dried to obtain the composite filler.
[0064] The method for surface modification of barium titanate-carbon nanotube composite filler using silane coupling agent includes: calcining the barium titanate-carbon nanotube composite filler at 500℃ to remove surface organic matter, then soaking it in 2mol / L NaOH solution to remove the coating layer, washing it until neutral, and drying it; mixing the silane coupling agent solution with the barium titanate-carbon nanotube composite filler, ultrasonically vibrating it for 10 hours to promote the reaction, centrifuging to separate the unreacted coupling agent, washing it three times with acetone and n-hexane, and vacuum drying it at 60℃ for 10 hours to obtain the modified product.
[0065] Example 1 S1. 100 parts of bisphenol A type epoxy resin (epoxy equivalent 180-220 g / eq) and 10 parts of vinylidene fluoride (fluorine content 40 wt%) are copolymerized at 80°C for 2 hours.
[0066] S2. Add 5 parts of aromatic amine (m-phenylenediamine) to the reaction product obtained in step S1, and react at 100°C for 1 hour to introduce a conjugated structure. S3. Add 10 parts of barium titanate-carbon nanotube composite filler modified with KH-550 silane coupling agent to the product obtained in step S2 (barium titanate to carbon nanotube mass ratio 7:3, composite filler particle size 50-100nm, KH-550 addition amount is 10% of the composite filler mass), ultrasonically disperse for 30 minutes at 300W power, then pre-cur at 80℃ for 1 hour, then heat to 140℃ for 2 hours, then cast into a film with a thickness of 1mm, and let stand for 24 hours at 25℃ and 50% relative humidity.
[0067] S4. Anneal the product obtained in step S3 at 80°C under nitrogen protection for 2 hours.
[0068] S5. The product obtained in step S4 is subjected to plasma treatment, wherein the plasma treatment power is 100W and the time is 5 minutes.
[0069] The test results of the epoxy resin prepared in this embodiment are as follows: dielectric constant ε = 10.2 (1MHz), dielectric loss tanδ = 0.025, tensile strength 92MPa, elongation at break 8.5%, and volume resistivity = 5.2 × 10⁻⁶. 4 Ω·cm.
[0070] Example 2 S1. 100 parts of bisphenol A type epoxy resin (epoxy equivalent 180-220 g / eq) and 8 parts of vinylidene fluoride (fluorine content 35 wt%) were copolymerized at 90°C for 2.5 hours.
[0071] S2. Add 6 parts of aromatic amine (p-phenylenediamine) to the reaction product obtained in step S1, and react at 110°C for 1.5 hours to introduce a conjugated structure. S3. Add 12 parts of barium titanate-carbon nanotube composite filler modified with KH-560 silane coupling agent to the product obtained in step S2 (barium titanate to carbon nanotube mass ratio 6:4, composite filler particle size 60-120nm, KH-560 addition amount is 12% of the composite filler mass), ultrasonically disperse at 350W for 25 minutes, then pre-cur at 85℃ for 1.5 hours, then heat to 130℃ for 2.5 hours, then cast into a film with a thickness of 1.5mm, and let stand for 24 hours at 25℃ and 50% relative humidity.
[0072] S4. Anneal the product obtained in step S3 at 75°C under nitrogen protection for 2.5 hours.
[0073] S5. The product obtained in step S4 is subjected to plasma treatment, wherein the plasma treatment power is 80W and the time is 6 minutes.
[0074] The test results of the epoxy resin prepared in this embodiment are as follows: dielectric constant ε = 9.8 (1MHz), dielectric loss tanδ = 0.028, tensile strength 88MPa, elongation at break 7.8%, and volume resistivity = 3.1×10⁻⁶. 5 Ω·cm.
[0075] Example 3 S1. 100 parts of bisphenol A type epoxy resin (epoxy equivalent 180-220 g / eq) and 6 parts of vinylidene fluoride (fluorine content 30 wt%) were copolymerized at 100°C for 3 hours.
[0076] S2. Add 4 parts of aromatic amine (o-phenylenediamine) to the reaction product obtained in step S1, and react at 120°C for 2 hours to introduce a conjugated structure. S3. Add 8 parts of barium titanate-carbon nanotube composite filler modified with KH-570 silane coupling agent to the product obtained in step S2 (barium titanate to carbon nanotube mass ratio 8:2, composite filler particle size 70-150nm, KH-570 addition amount is 8% of the composite filler mass), ultrasonically disperse for 35 minutes at 250W power, then pre-cur at 90℃ for 2 hours, then heat to 120℃ for 3 hours, then cast into a film with a thickness of 2mm, and let stand for 24 hours at 25℃ and 50% relative humidity.
[0077] S4. Anneal the product obtained in step S3 at 70°C under nitrogen protection for 3 hours.
[0078] S5. The product obtained in step S4 is subjected to plasma treatment, wherein the plasma treatment power is 60W and the time is 7 minutes.
[0079] The test results of the epoxy resin prepared in this embodiment are as follows: dielectric constant ε = 8.5 (1MHz), dielectric loss tanδ = 0.032, tensile strength 85MPa, elongation at break 6.5%, and volume resistivity = 1.2 × 10⁻⁶. 6 Ω·cm.
[0080] Comparative Example 1 The curing process did not involve gradient heating and the barium titanate-carbon nanotube composite filler was not modified.
[0081] The specific process includes: S1. 100 parts of bisphenol A type epoxy resin (epoxy equivalent 180-220 g / eq) and 6 parts of vinylidene fluoride (fluorine content 30 wt%) were copolymerized at 100°C for 3 hours.
[0082] S2. Add 4 parts of aromatic amine (o-phenylenediamine) to the reaction product obtained in step S1, and react at 120°C for 2 hours to introduce a conjugated structure. S3. Add 8 parts of unmodified barium titanate-carbon nanotube composite filler (barium titanate to carbon nanotube mass ratio 8:2, composite filler particle size 70-150nm) to the product obtained in step S2, ultrasonically disperse at 250W for 35 minutes, then heat to 120℃ and cure for 5 hours, then cast into a film with a thickness of 2mm, and let stand for 24 hours at 25℃ and 50% relative humidity.
[0083] S4. Anneal the product obtained in step S3 at 70°C under nitrogen protection for 3 hours.
[0084] S5. The product obtained in step S4 is subjected to plasma treatment, wherein the plasma treatment power is 60W and the time is 7 minutes.
[0085] The test results of the epoxy resin prepared in this comparative example are as follows: dielectric constant ε = 6.2 (1MHz), dielectric loss tanδ = 0.035, tensile strength 81MPa, elongation at break 6.2%, and volume resistivity = 3.6 × 10⁻⁶. 7 Ω·cm.
[0086] As can be seen from the examples and comparative examples, the method described in Examples 1-3, through gradient temperature curing and surface modification of the barium titanate-carbon nanotube composite filler, results in higher dielectric constant and conductivity, achieving a balance between dielectric constant and conductivity. In contrast, Comparative Example 1, without gradient temperature curing and without modification of the barium titanate-carbon nanotube composite filler, exhibits lower dielectric constant and conductivity. Therefore, the epoxy resin prepared using the method of this invention exhibits superior performance.
[0087] It should be understood that any parts not described in detail in this specification belong to the prior art.
[0088] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing a high-dielectric-high-conductivity epoxy resin, characterized in that, The method includes the following steps: (1) Copolymerize bisphenol A type epoxy resin with polytetrafluoroethylene at 80-100℃ for 2-3 hours; (2) Add aromatic amines to the reaction product obtained in step (1) to carry out the reaction; (3) Add surface-modified barium titanate-carbon nanotube composite filler to the product obtained in step (2), and cure by ultrasonication and gradient heating, and then cast into shape. (4) Anneal the product obtained in step (3); (5) The product obtained in step (4) is subjected to plasma treatment.
2. The method according to claim 1, characterized in that, The weight ratio of the bisphenol A epoxy resin, the polytetrafluoroethylene, the aromatic amine, and the surface-modified barium titanate-carbon nanotube composite filler is 100:6-10:4-6:8-12.
3. The method according to claim 1 or 2, characterized in that, The epoxy equivalent of the bisphenol A type epoxy resin is 180-220 g / eq; And / or, the fluorine content of the polytetrafluoroethylene is 30-50 wt%.
4. The method according to any one of claims 1-3, characterized in that, The aromatic amine is selected from at least one of m-phenylenediamine, p-phenylenediamine, and o-phenylenediamine; And / or, in step (2), the reaction conditions include: a temperature of 100-120°C and a time of 1-2 hours.
5. The method according to any one of claims 1-4, characterized in that, The surface modifier for surface modification of barium titanate-carbon nanotube composite filler is a silane coupling agent; And / or, in the barium titanate-carbon nanotube composite filler, the mass ratio of barium titanate to carbon nanotubes is 1.5-4:1; And / or, the preparation process of the barium titanate-carbon nanotube composite filler includes: ultrasonically treating carbon nanotubes in a mixed solution of concentrated hydrochloric acid and concentrated sulfuric acid for 30 minutes, then refluxing at 65°C for 4 hours, then washing and drying to obtain hydroxylated carbon nanotubes; then mixing Ba(OH)2 aqueous solution containing TiO2 particles with hydroxylated carbon nanotubes and carrying out a hydrothermal reaction at 380-450°C and 30-50 MPa for 8-24 hours to allow barium titanate to crystallize on the surface of carbon nanotubes, and then filtering, washing and drying after cooling to obtain the composite filler.
6. The method according to claim 5, characterized in that, The silane coupling agent is at least one of KH-550, KH-560 and KH-570; And / or, the amount of the surface modifier is 5-15% by weight of the barium titanate-carbon nanotube composite filler.
7. The method according to any one of claims 1-6, characterized in that, In step (3), the conditions for ultrasound include: power of 250-350W and time of 25-35 minutes.
8. The method according to any one of claims 1-7, characterized in that, In step (3), the gradient temperature curing process includes: first pre-curing at 80-90℃ for 1-2 hours; then heating to 140℃ for 2-3 hours; And / or, in step (3), after casting, let stand for 15-40 hours at 15-40℃ and 40-70% relative humidity.
9. The method according to any one of claims 1-8, characterized in that, In step (4), the annealing conditions include: a temperature of 70-80℃ and a time of 2-3 hours.
10. The method according to any one of claims 1-9, characterized in that, In step (5), the conditions for plasma treatment include: power of 60-100W and time of 5-7 minutes.