Preparation method and application of ETFE film with extremely low dielectric loss

Abstract

The invention provides a preparation method and application of an ETFE film with extremely low dielectric loss, and the preparation method comprises the following steps: introducing a low-dielectric filler into ETFE resin through melt blending to obtain a composite resin system; the melting temperature is controlled to be 220-240 DEG C, the rotating speed of a screw is controlled to be 30-50 rpm, the cooling rate is controlled to be 8-12 DEG C / s, the crystallinity of the film is controlled to be 30-40%, and the composite resin system is subjected to melt extrusion to form the film; carrying out gradient plasma surface modification and vacuum annealing treatment on the film in sequence; and finally, the ETFE film with extremely low dielectric loss is obtained. The dielectric loss factor of the ETFE film is less than or equal to 0.001. According to the ETFE film prepared by the method, the dielectric constant epsilon r is 2.0-2.2, the dielectric loss factor is less than or equal to 0.001, the tear strength is greater than or equal to 120mN, and the temperature resistance range is-200 DEG C to + 150 DEG C.

Description

Technical Field

[0001] This invention relates to the fields of polymer material processing and fluoroplastic film preparation technology, specifically to a method for preparing an ETFE film with extremely low dielectric loss and its application. Background Technology

[0002] ETFE film, with its excellent high-frequency electrical properties, weather resistance, lightweight characteristics and chemical stability, has become one of the key materials for packaging lightweight components in high-frequency electronic and electrical communication. In 5G / 6G communication, its low dielectric loss characteristics directly reduce the energy loss of high-frequency signals and improve the signal quality and transmission rate of communication components.

[0003] To further reduce the dielectric loss of ETFE films, current efforts mainly focus on raw material modification and process optimization, but certain shortcomings still exist, such as: Blending modification: By adding low-dielectric inorganic nanofillers (such as SiO2, BN, Al2O3) or organic polymers (such as polyphenylene ether), the polarity of the resin is reduced; however, there are problems such as uneven dispersion of fillers and enhanced interfacial polarization, which can easily lead to fluctuations in dielectric loss and make it impossible to achieve stable ultra-low dielectric loss performance. Copolymerization modification: When introducing fluorinated / low-polar monomers (such as hexafluoropropylene) to participate in copolymerization and reducing the molecular dipole moment, the original weather resistance or mechanical flexibility of the ETFE membrane may be sacrificed, resulting in an imbalance of overall performance and making it difficult to balance low loss and basic performance. Process control: When optimizing casting / biaxial stretching film formation parameters (such as stretching ratio and temperature gradient) to promote molecular chain orientation and reduce free volume, the control precision for extremely low loss (<0.0002) is insufficient and it is easy to cause uneven film thickness. At the same time, it is difficult to achieve both low loss and high production efficiency, which limits the practicality of production. It can be seen that existing technologies suffer from bottlenecks such as poor filler dispersion, unbalanced overall performance after modification, and difficulty in balancing low loss and high production efficiency. These limitations make it difficult to meet the stringent requirements of extremely low loss and stable operation in high-frequency scenarios such as 5G / satellite communication. Therefore, developing a method for preparing an extremely low dielectric loss ETFE film that can solve the above problems has significant practical significance and application value. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing an ETFE film with extremely low dielectric loss and its application. In this method, through systematic optimization of the entire process of raw materials, processes and post-processing, the problems of poor filler dispersion, unbalanced comprehensive performance and difficulty in balancing low loss and high production efficiency in the prior art are solved. The method achieves extremely low dielectric loss, excellent comprehensive performance and efficient and controllable production of ETFE film. The obtained ETFE film is suitable for packaging applications of lightweight components in high-frequency electronic and electrical and communication applications.

[0005] The technical solution of the present invention is as follows: Firstly, a method for preparing an ETFE film with extremely low dielectric loss is described below: Step 1: Prepare materials ETFE resin is used as the matrix, and a low dielectric filler is introduced into it by melt blending. The low dielectric filler is 10-20% of the mass of ETFE resin to obtain a composite resin system. Step 2, melt extrusion The composite resin system is melt-extruded into a film; the melt temperature is controlled at 220-240℃, the screw speed at 30-50rpm, the cooling rate at 8-12℃ / s, and the film crystallinity is adjusted to 30-40%. The film formation process employs a low-temperature, low-speed process to suppress excessive orientation of molecular chains and regulate crystallinity to 30%-40%; simultaneously, the cooling rate is increased to 8-12℃ / s to block the local aggregation of polar groups during the cooling process and reduce dielectric loss caused by structural defects. Step 3, Post-processing The extruded film was subjected to gradient plasma surface modification and vacuum annealing treatment in sequence. The gradient plasma surface modification process involves an argon atmosphere in the first stage with a power of 80-100W, and a mixed gas atmosphere of argon and hydrogen in the second stage with a power of 50-80W. The total processing time is 5-10 minutes, and the etching depth is controlled to be ≤10nm. Gradient plasma treatment is used to remove surface impurities while controlling the etching depth to ≤10nm, thus avoiding a decrease in the mechanical strength of the thin film. Vacuum annealing treatment, temperature 120-140℃, treatment time 2-4h; In the post-processing, gradient plasma treatment removes surface polar impurities and weak interface layers through high-energy particle bombardment; vacuum annealing promotes the release of internal stress and optimizes the regularity of molecular chain stacking. The final result is an ETFE film with extremely low dielectric loss; the dielectric loss factor of the ETFE film is ≤0.001.

[0006] Preferably, in step one, the content of metal ions and polar groups in the ETFE resin is ≤50ppm; the low dielectric filler is hollow glass microspheres and / or fluorine-modified silica.

[0007] Preferably, in step one, the ETFE resin is Chemours Tefzel® 200, Asahi Glass Fluon8LM-E, or a modified version of Chemours Tefzel® 200, and the content of metal ions and polar groups in the modified Chemours Tefzel® 200 ETFE resin is ≤10ppm.

[0008] Preferably, in step one, the melt blending adopts a twin-screw pulse shear blending method, and the blending frequency is 10-15Hz.

[0009] Preferably, in step two, the melting temperature is 220-230℃, the screw speed is 30-40 rpm, the cooling rate is 8-12℃ / s, and the crystallinity of the film is adjusted to 30-35%.

[0010] Preferably, in step three, the gradient plasma surface modification process has a first-stage treatment time of 2-4 minutes and a second-stage treatment time of 3-6 minutes.

[0011] Preferably, in step three, the hydrogen gas component in the argon-hydrogen mixture is 60-80%.

[0012] Preferably, in step three, the vacuum annealing temperature is 130-140℃ and the processing time is 3 hours.

[0013] Secondly, the ETFE film prepared using the above method has a dielectric constant ε. r It has a strength of 2.0-2.2, dielectric loss factor ≤0.001, tear strength ≥120mN, and temperature range of -200℃ to +150℃.

[0014] Applications of the aforementioned ETFE film in the packaging of lightweight components for high-frequency electronic, electrical, and / or communication devices; The lightweight communication components include a 5G / 6G base station millimeter-wave antenna radome, a satellite communication antenna radome, and a fiber optic bundle sheath. The 5G / 6G base station millimeter-wave antenna radome made using the ETFE film of this invention can achieve efficient signal transmission while resisting outdoor ultraviolet radiation, rain, and dust erosion. The satellite communication antenna radome made using the ETFE film of this invention can meet aerospace-grade lightweight requirements and withstand high and low temperature cycling and atomic oxygen erosion in space. The fiber optic bundle sheath made using the ETFE film of this invention is a lightweight sheath that can reduce the overall weight of fiber optic communication cables and is suitable for airborne / spaceborne communication systems.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Co-design of raw materials and fillers: ETFE resin (Chemours Tefzel® 200 modified version) with metal ion and polar group content ≤10ppm is selected. The content of metal ions and polar groups is strictly controlled to avoid residual impurities increasing dielectric loss through dipole polarization. Low dielectric fillers are introduced into the ETFE resin through twin-screw pulse shear blending to increase the dielectric constant ε. r The concentration was reduced to 2.0-2.2, which resolved the contradiction between filler dispersion and interfacial polarization.

[0016] 2. By adopting a low-temperature, low-speed melt extrusion process, the orientation of molecular chains is suppressed while improving crystal regularity. Simultaneously, the cooling rate is increased, local aggregation of polar groups during the cooling process is blocked, and dielectric loss caused by structural defects is reduced. While ensuring low dielectric loss, production efficiency is increased by 40%.

[0017] 3. Multi-stage defect repair: In gradient plasma surface modification, the first stage mainly removes polar impurities and weak interface layers from the film surface. In the second stage, the addition of hydrogen can further optimize the chemical state of the film surface, reduce polarization sites, and control the etching depth to ≤10nm to avoid a decrease in the mechanical strength of the film. Vacuum annealing can promote the release of internal stress in the film and optimize the regularity of molecular chain stacking, further reducing dielectric loss.

[0018] A multi-stage post-treatment process combining gradient plasma surface modification and vacuum annealing was adopted to achieve a repair rate of ≥95% for the ETFE film; the resulting ETFE film had a tear strength of ≥120mN.

[0019] 4. Using the method of this invention, breakthroughs have been achieved in extremely low dielectric loss, balanced overall performance, and highly efficient and controllable process. The prepared ETFE film has a dielectric constant ε. r With a strength of 2.0-2.2, dielectric loss factor ≤0.001, tear strength ≥120mN, and temperature range of -200℃ to +150℃, it has excellent weather resistance, chemical corrosion resistance, and mechanical flexibility, making it suitable for the high-frequency service requirements of 5G base stations for more than 10 years. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0021] Example 1 A method for preparing an ETFE film with extremely low dielectric loss is as follows: Step 1: Prepare materials Chemours Tefzel® 200 ETFE resin with a metal ion and polar group content of 45 ppm was used as the matrix. Low dielectric filler was introduced into it by twin-screw pulse shear blending at a blending frequency of 12 Hz to obtain a composite resin system. The low-dielectric filler is 12% of the mass of ETFE resin, resulting in a composite resin system; the low-dielectric filler is a fluorine-modified silica filler. Step 2, melt extrusion The composite resin system was melt-extruded into a film; the melt temperature was controlled at 225℃, the screw speed at 35 rpm, the cooling rate at 10℃ / s, and the film crystallinity was adjusted to 32%. The film formation process employs a low-temperature, low-speed process to suppress excessive molecular chain orientation and regulate crystallinity; simultaneously, it increases the cooling rate to block the local aggregation of polar groups during the cooling process and reduce dielectric loss caused by structural defects. Step 3, Post-processing The extruded film was subjected to gradient plasma surface modification and vacuum annealing treatment in sequence. The gradient plasma surface modification process involves two stages: the first stage is in an argon atmosphere with a power of 90W and a processing time of 3 minutes; the second stage is in a mixed gas atmosphere of argon and hydrogen with a power of 60W and a processing time of 4 minutes, controlling the etching depth to 8nm. In the second stage, the volume fraction of hydrogen in the argon-hydrogen mixture is 70%. Gradient plasma treatment is used to remove surface impurities while controlling the etching depth, thus avoiding a decrease in the mechanical strength of the thin film. Vacuum annealing was performed at 130℃ for 3 hours. In the post-processing, gradient plasma treatment removes surface polar impurities and weak interface layers through high-energy particle bombardment; vacuum annealing promotes the release of internal stress and optimizes the regularity of molecular chain stacking. Ultimately, an ETFE film with extremely low dielectric loss was obtained; Testing revealed that the ETFE film prepared using the above method has a dielectric constant ε. r It has a strength of 2.1, a dielectric loss factor of 0.0008, a tear strength of 125mN, and a temperature range of -200℃ to +150℃, meeting the high-frequency service requirements of 5G base stations.

[0022] Example 2 A method for preparing an ETFE film with extremely low dielectric loss is as follows: Step 1: Prepare materials A modified ETFE resin of Chemours Tefzel® 200 with a metal ion and polar group content of 8 ppm was used as the matrix. Low dielectric filler was introduced into it by twin-screw pulse shear blending at a blending frequency of 15 Hz to obtain a composite resin system. The low-dielectric filler is 18% of the mass of ETFE resin, resulting in a composite resin system; the low-dielectric filler is a fluorine-modified silica filler. Step 2, melt extrusion The composite resin system was melt-extruded into a film; the melt temperature was controlled at 228℃, the screw speed at 38 rpm, the cooling rate at 11℃ / s, and the film crystallinity was adjusted to 34%. The film formation process employs a low-temperature, low-speed process to suppress excessive molecular chain orientation and regulate crystallinity; simultaneously, it increases the cooling rate to block the local aggregation of polar groups during the cooling process and reduce dielectric loss caused by structural defects. Step 3, Post-processing The extruded film was subjected to gradient plasma surface modification and vacuum annealing treatment in sequence. The gradient plasma surface modification process involves two stages: the first stage is an argon atmosphere with a power of 100W and a processing time of 4 minutes; the second stage is a mixed gas atmosphere of argon and hydrogen with a power of 70W and a processing time of 5 minutes, controlling the etching depth to 9nm. In the second stage, the volume fraction of hydrogen in the argon-hydrogen mixture is 60%. Gradient plasma treatment is used to remove surface impurities while controlling the etching depth, thus avoiding a decrease in the mechanical strength of the thin film. Vacuum annealing was performed at 135℃ for 3 hours. In the post-processing, gradient plasma treatment removes surface polar impurities and weak interface layers through high-energy particle bombardment; vacuum annealing promotes the release of internal stress and optimizes the regularity of molecular chain stacking. Ultimately, an ETFE film with extremely low dielectric loss was obtained; The ETFE film prepared using the above method has a dielectric constant ε. r It has a dielectric constant of 2.05, a dielectric loss factor of 0.0007, a tear strength of 130mN, and a temperature range of -200℃ to +150℃, exhibiting superior dielectric and mechanical properties.

[0023] Example 3 A method for preparing an ETFE film with extremely low dielectric loss is as follows: Step 1: Prepare materials Asahi Glass Fluon 8LM-E ETFE resin with a metal ion and polar group content of 50 ppm was used as the matrix. Low dielectric filler was introduced into it by twin-screw pulse shear blending at a blending frequency of 10 Hz to obtain a composite resin system. The low-dielectric filler is 10% of the mass of ETFE resin, resulting in a composite resin system; the low-dielectric filler is hollow glass microspheres. Step 2, melt extrusion The composite resin system was melt-extruded into a film; the melt temperature was controlled at 220℃, the screw speed at 30rpm, the cooling rate at 8℃ / s, and the film crystallinity was adjusted to 30%. The film formation process employs a low-temperature, low-speed process to suppress excessive molecular chain orientation and regulate crystallinity; simultaneously, it increases the cooling rate to block the local aggregation of polar groups during the cooling process and reduce dielectric loss caused by structural defects. Step 3, Post-processing The extruded film was subjected to gradient plasma surface modification and vacuum annealing treatment in sequence. The gradient plasma surface modification process involves two stages: the first stage is an argon atmosphere with a power of 80W and a processing time of 2 minutes; the second stage is a mixed gas atmosphere of argon and hydrogen with a power of 50W and a processing time of 3 minutes, controlling the etching depth to 7nm. In the second stage, the volume fraction of hydrogen in the argon-hydrogen mixture is 80%. Gradient plasma treatment is used to remove surface impurities while controlling the etching depth, thus avoiding a decrease in the mechanical strength of the thin film. Vacuum annealing was performed at 120℃ for 2 hours. In the post-processing, gradient plasma treatment removes surface polar impurities and weak interface layers through high-energy particle bombardment; vacuum annealing promotes the release of internal stress and optimizes the regularity of molecular chain stacking. Ultimately, an ETFE film with extremely low dielectric loss was obtained; The ETFE film prepared using the above method has a dielectric constant ε. r It has a strength of 2.2, a dielectric loss factor of 0.0009, a tear strength of 120mN, and a temperature range of -200℃ to +150℃, meeting the basic requirements for high-frequency packaging.

[0024] Example 4 A method for preparing an ETFE film with extremely low dielectric loss is as follows: Step 1: Prepare materials Using Chemours Tefzel® 200 ETFE resin with a metal ion and polar group content of 40 ppm as the matrix, a low dielectric filler was introduced into it by twin-screw pulse shear blending at a blending frequency of 10 Hz to obtain a composite resin system. The low dielectric filler is 20% of the mass of ETFE resin, resulting in a composite resin system. The low dielectric filler is a composite filler of hollow glass microspheres and fluorine-modified silica, with a mass ratio of 1:1 between the hollow glass microspheres and the fluorine-modified silica. Step 2, melt extrusion The composite resin system was melt-extruded into a film; the melt temperature was controlled at 240℃, the screw speed at 50rpm, the cooling rate at 12℃ / s, and the film crystallinity was adjusted to 40%. The film formation process employs a low-temperature, low-speed process to suppress excessive molecular chain orientation and regulate crystallinity; simultaneously, it increases the cooling rate to block the local aggregation of polar groups during the cooling process and reduce dielectric loss caused by structural defects. Step 3, Post-processing The extruded film was subjected to gradient plasma surface modification and vacuum annealing treatment in sequence. The gradient plasma surface modification process involves two stages: the first stage is an argon atmosphere with a power of 100W and a processing time of 5 minutes; the second stage is a mixed gas atmosphere of argon and hydrogen with a power of 80W and a processing time of 5 minutes, controlling the etching depth to 10nm. In the second stage, the volume fraction of hydrogen in the argon-hydrogen mixture is 70%. Gradient plasma treatment is used to remove surface impurities while controlling the etching depth, thus avoiding a decrease in the mechanical strength of the thin film. Vacuum annealing was performed at 140℃ for 4 hours. In the post-processing, gradient plasma treatment removes surface polar impurities and weak interface layers through high-energy particle bombardment; vacuum annealing promotes the release of internal stress and optimizes the regularity of molecular chain stacking. Ultimately, an ETFE film with extremely low dielectric loss was obtained; The ETFE film prepared using the above method has a dielectric constant ε. r It has a strength of 2.15, a dielectric loss factor of 0.00085, a tear strength of 128mN, and a temperature range of -200℃ to +150℃, exhibiting excellent overall performance.

[0025] Comparative Example 1 In this comparative example, the ETFE membrane was prepared using a blending modification method in the prior art, specifically as follows: Ordinary ETFE resin with a metal ion and polar group content of 100 ppm was used as the matrix; SiO2 filler (15% of the mass of ETFE resin) is introduced into the resin through conventional melt blending. An ETFE film was obtained by conventional melt extrusion process with a melt temperature of 250℃, a screw speed of 60rpm, and a cooling rate of 5℃ / s, without post-treatment. The dielectric constant ε of the ETFE film was measured. r The dielectric loss factor is 0.002, the tear strength is 90mN, and there are problems such as uneven filler dispersion and large film thickness deviation, which make it difficult to meet the usage requirements of 5G high-frequency scenarios.

[0026] Compared with Comparative Example 1, the ETFE film prepared in the embodiments of the present invention has significant advantages in terms of dielectric constant, dielectric loss factor, and mechanical strength. Moreover, the film has stable performance and high production efficiency, which can effectively solve the bottleneck problems existing in the prior art.

[0027] In this invention, hollow glass microspheres and / or fluorine-modified silica are used as low dielectric fillers, and they are introduced into ETFE resin by twin-screw pulse shear blending. This overcomes the strong coupling contradiction between filler addition amount and dispersibility and mechanical properties, and achieves nanoscale uniform dispersion of fillers. During film formation, a low-temperature and low-speed process is adopted to suppress excessive orientation of molecular chains and regulate crystallinity; the cooling rate is controlled simultaneously to avoid the generation of internal stress while blocking the local aggregation of polar groups during the cooling process, reducing dielectric loss caused by structural defects, improving process stability, and making the process repeatable. In the post-processing, gradient plasma treatment is used to remove surface polar impurities and weak interface layers by bombarding with high-energy particles; vacuum annealing promotes the release of internal stress and optimizes the regularity of molecular chain stacking, thereby achieving precise modification of the surface / internal molecular state of the ETFE film. The method of this invention achieves the maintenance of ETFE's original temperature resistance (-200℃~+150℃), chemical corrosion resistance and bending resistance on the basis of low loss, while ensuring stable loss performance under long-term high-frequency environment (such as 5G base stations for more than 10 years), and a leap from single low loss to high performance balance.

[0028] Although the present invention has been described in detail with reference to preferred embodiments, it is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an ETFE film with extremely low dielectric loss, characterized in that, The process is as follows: Step 1: Prepare materials ETFE resin is used as the matrix, and a low dielectric filler is introduced into it by melt blending. The low dielectric filler is 10-20% of the mass of ETFE resin to obtain a composite resin system. Step 2, melt extrusion The composite resin system is melt-extruded into a film; the melt temperature is controlled at 220-240℃, the screw speed at 30-50rpm, the cooling rate at 8-12℃ / s, and the film crystallinity is adjusted to 30-40%. Step 3, Post-processing The extruded film was subjected to gradient plasma surface modification and vacuum annealing treatment in sequence. The gradient plasma surface modification process involves an argon atmosphere in the first stage with a power of 80-100W, and a mixed gas atmosphere of argon and hydrogen in the second stage with a power of 50-80W. The total processing time is 5-10 minutes, and the etching depth is controlled to be ≤10nm. Vacuum annealing treatment, temperature 120-140℃, treatment time 2-4h; The final result is an ETFE film with extremely low dielectric loss; the dielectric loss factor of the ETFE film is ≤0.

001.

2. The method for preparing an ultra-low dielectric loss ETFE film as described in claim 1, characterized in that, In step one, the content of metal ions and polar groups in the ETFE resin is ≤50ppm; the low dielectric filler is hollow glass microspheres and / or fluorine-modified silica.

3. The method for preparing the ultra-low dielectric loss ETFE film as described in claim 1, characterized in that, In step one, the ETFE resin is Chemours Tefzel® 200, Asahi Glass Fluon8LM-E, or a modified version of Chemours Tefzel® 200, and the content of metal ions and polar groups in the modified Chemours Tefzel® 200 ETFE resin is ≤10ppm.

4. The method for preparing an ultra-low dielectric loss ETFE film as described in claim 1, characterized in that, In step one, the melt blending is performed using a twin-screw pulse shear blending method with a blending frequency of 10-15 Hz.

5. The method for preparing an ultra-low dielectric loss ETFE film as described in claim 1, characterized in that, In step two, the melting temperature is 220-230℃, the screw speed is 30-40 rpm, the cooling rate is 8-12℃ / s, and the crystallinity of the film is adjusted to 30-35%.

6. The method for preparing an ultra-low dielectric loss ETFE film as described in claim 1, characterized in that, In step three, gradient plasma surface modification is performed. The first stage of the treatment takes 2-4 minutes, and the second stage takes 3-6 minutes.

7. The method for preparing an ultra-low dielectric loss ETFE film as described in claim 1, characterized in that, In step three, the hydrogen component in the argon-hydrogen mixture is 60-80%.

8. The method for preparing an ultra-low dielectric loss ETFE film as described in claim 1, characterized in that, In step three, the vacuum annealing temperature is 130-140℃ and the treatment time is 3 hours.

9. The application of the ETFE film prepared using the method for preparing the ultra-low dielectric loss ETFE film as described in claim 1 in the packaging of lightweight components for high-frequency electronic and / or communication applications.