Polyamide material with low dielectric constant

Abstract

The invention discloses a low-dielectric-constant polyamide material, and relates to the technical field of high polymer materials. The invention discloses a low-dielectric-constant polyamide material. The composite material is prepared from the following raw materials in parts by weight: 35 to 45 parts of polyamide 66, 5 to 10 parts of polytetrafluoroethylene micro powder, 8 to 12 parts of modified porous siloxane microspheres, 3 to 7 parts of modified nano zinc oxide, 10 to 15 parts of glass fibers, 4 to 8 parts of polyether-ether-ketone, 1 to 3 parts of graphene nanosheets, 3 to 5 parts of fluororubber, 1 to 2 parts of a titanate coupling agent, 0.3 to 0.7 part of an antioxidant 1010, 0.5 to 1.0 part of ethylene bis stearamide and 0.1 to 0.3 part of an ultraviolet absorbent UV-531. The low-dielectric-constant polyamide material has the remarkable advantages that the raw materials are scientifically proportioned, and various modified components are contained to enhance the performance; all the components are subjected to special treatment, so that the compatibility is good; the preparation process is rigorous, and the material has excellent dielectric properties; and the material also has good heat resistance and weather resistance and strong mechanical properties, and is suitable for various scenes with high dielectric constant requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular materials, in particular to a low dielectric constant polyamide material. BACKGROUND

[0002] With the rapid development of electronic information industry, especially the continuous breakthrough in the fields of 5G communication, high-frequency integrated circuit, flexible electronics, etc., more stringent requirements are put forward for the performance of electronic packaging materials. Among them, low dielectric constant materials can effectively reduce signal transmission loss and improve signal propagation speed, and become one of the key materials in the field of high-frequency electronic device packaging.

[0003] Polyamide materials are widely used in the field of electronic packaging due to their excellent mechanical properties, heat resistance, chemical corrosion resistance and good processability. However, the dielectric constant of traditional polyamide materials is relatively high, usually between 3.5-4.5, which cannot meet the demand of low dielectric constant for high-frequency signal transmission, limiting its further application in high-end electronic devices.

[0004] In order to reduce the dielectric constant of polyamide materials, the existing technology often uses methods such as adding low dielectric fillers such as hollow microspheres and fluorides, or introducing low-polarity groups containing fluorine and silicon. However, these methods have many shortcomings: for example, simply adding inorganic fillers can easily lead to poor material interface compatibility and cause mechanical property decline; the introduction of low-polarity groups may damage the molecular chain structure of polyamide, reducing its heat resistance and mechanical strength; some modification processes are complex, high in production cost, and difficult to achieve industrial mass production.

[0005] In addition, electronic packaging materials also need to have good weather resistance, oxidation resistance and dimensional stability to adapt to complex use environments. While optimizing dielectric properties, traditional modified polyamide materials often sacrifice other key properties, making it difficult to achieve synergistic improvement of dielectric properties and comprehensive performance. Therefore, developing a polyamide material with low dielectric constant, excellent mechanical properties, good heat and weather resistance, and stable preparation process has become a research hotspot and urgent need in the field of high molecular materials. SUMMARY

[0006] In view of the shortcomings of the prior art, the present application provides a low dielectric constant polyamide material, which solves the problems of high dielectric constant of traditional polyamide, poor compatibility of fillers and matrix, poor mechanical properties, and complex process and high cost.

[0007] To achieve the above purpose, the present application is realized by the following technical scheme: A low dielectric constant polyamide material, comprising the following raw materials by weight: 35-45 parts of polyamide 66, 5-10 parts of polytetrafluoroethylene micro powder, 8-12 parts of modified porous siloxane microspheres, 3-7 parts of modified nano zinc oxide, 10-15 parts of glass fiber, 4-8 parts of polyether ether ketone, 1-3 parts of graphene nanosheet, 3-5 parts of fluororubber, 1-2 parts of titanate coupling agent, 0.3-0.7 parts of antioxidant 1010, 0.5-1.0 parts of ethylene bis stearamide, and 0.1-0.3 parts of ultraviolet absorber UV-531.

[0008] Further, the particle size of the polytetrafluoroethylene micro powder is 1-5 μm, and its surface is pretreated with silane coupling agent KH-550, which can improve the compatibility with the matrix, further reduce the dielectric constant of the material and enhance the chemical resistance; the pretreatment method is as follows: the polytetrafluoroethylene micro powder is added into a 3% silane coupling agent KH-550 ethanol solution, ultrasonic dispersion is carried out for 15 min, then stirring reaction is carried out at 60℃ for 2h, after filtration, vacuum drying is carried out at 80℃ for 3h, to obtain surface modified polytetrafluoroethylene micro powder.

[0009] Further, the glass fiber is alkali-free glass fiber, and the aspect ratio is 10-20, and is treated with silane coupling agent KH-550, which can enhance the mechanical strength and dimensional stability of the material; the treatment process is as follows: the glass fiber is added into a 2% silane coupling agent KH-550 aqueous solution, stirring is carried out at 50℃ for 30 min, after filtration, drying is carried out at 110℃ for 2h, and then cooling is carried out for standby.

[0010] Further, the graphene nanosheet is single-layer graphene, the thickness is ≤5 nm, and the lateral size is 1-5 μm, and its surface is modified with cetyltrimethylammonium bromide, which can improve the dispersibility, enhance the thermal conductivity and mechanical properties of the material; the modification method is as follows: the graphene nanosheet is added into a 0.5% cetyltrimethylammonium bromide aqueous solution, ultrasonic treatment is carried out for 30 min, centrifugal separation is carried out at 7000 r / min for 15 min, then washing is carried out with deionized water until no bromide ion is detected, and then vacuum drying is carried out at 60℃ for 4h.

[0011] Further, the modified porous siloxane microspheres are prepared by the following steps: A1, the pore size of 15 nm porous siloxane microspheres is added to a mixed solution A prepared by mixing 8% ammonium fluoride solution and 5% hydrochloric acid solution at a volume ratio of 2:1, stirred at 200 r / min for 50 min at 25℃, then heated to 40℃ at a rate of 1℃ / min, continue to stir for 30 min, take sample every 15 min to detect the pore size by laser particle size analyzer, finally control the pore size to be 25-30 nm, the expanded porous structure can introduce more low dielectric air phase, which lays the foundation for reducing the dielectric constant of the material; after the reaction is completed, wash with deionized water until the pH of the filtrate is 7, then add deionized water and ultrasonic for 20 min to form a uniform suspension, centrifuge the suspension at 3000 r / min for 15 min, pour off the supernatant, and the precipitate is dried at 60℃ under-0.09 MPa vacuum for 5 h to obtain the first modified microspheres; A2, configure a mixed solution B containing tridecafluorooctyltriethoxysilane, methacryloxypropyltrimethoxysilane and p-toluenesulfonic acid, the solvent is cyclohexane, add the first modified microspheres to the mixed solution, heat to 80℃ under nitrogen protection, add azobisisobutyronitrile in three times, each interval is 30 min, stir at 300 r / min for 5 h, introduce fluorine group to further reduce dielectric properties, at the same time, improve the chemical compatibility with the matrix resin through methacryloxy group, and reduce the interface defects; after the reaction is completed, first collect the microspheres by hot Buchner funnel filtration, wash the filter cake with cyclohexane for 2 times, then transfer the microspheres to a beaker, add cyclohexane, stir and wash in a 80℃ constant temperature water bath for 3 times, each time for 30 min, and change new cyclohexane, finally dry at 70℃ for 4 h; A3, take the second modified microspheres and add to a mixed solution C containing divinylbenzene and benzophenone, the solvent is anhydrous ethanol, ultrasonic dispersion for 20 min to form a uniform suspension, transfer the dispersed system to a ultraviolet light reaction kettle, irradiate under nitrogen protection at a wavelength of 365 nm and a power of 200 W for 1 h, stir every 15 min, can form three-dimensional cross-linked structure to enhance the stability of the microspheres, avoid structure collapse in processing, at the same time, further optimize the interface combination with the matrix, and ensure the stability of low dielectric properties; after the end, centrifuge at 4000 r / min for 20 min, collect the microspheres, wash with anhydrous ethanol for 2 times, dry at 80℃ under-0.09 MPa vacuum for 6 h, to obtain modified porous siloxane microspheres.

[0012] Further, the amount of porous siloxane microspheres and mixed solution A in A1 is 80 g:400 mL; if the pore size is detected at 15 min, the pore size is only expanded to 18-20 nm, the stirring speed can be increased to 250 r / min; if the pore size is more than 25 nm at 30 min, enter the heating stage in advance.

[0013] Further, the use amount ratio of the mixed solution B, the first modified microspheres and the azobisisobutyronitrile in the A2 is 600 mL:60 g:0.9 g; the mass fractions of the tridecafluoro-1,1,2,2-ethyloctyltriethoxysilane, the methacryloxypropyltrimethoxysilane and the p-toluenesulfonic acid in the mixed solution B are 6%, 2% and 0.2% respectively, and the mass fractions are based on the total mass of the mixed solution B.

[0014] Further, the use amount ratio of the second modified microspheres and the mixed solution C in the A3 is 40 g:400 mL; the mass fractions of the divinylbenzene and the benzophenone in the mixed solution C are 5% and 0.3% respectively, and the mass fractions are based on the total mass of the mixed solution C.

[0015] Further, the modified nano zinc oxide is prepared according to the following steps: B1, the nano zinc oxide is added into an 8% potassium persulfate solution, stirred at 60°C and 250 r / min for 2 h, oxygen is introduced at a flow rate of 30 mL / min for 10 min every 30 min during the stirring, after the stirring, the pH is adjusted to 3.0 by using 1 mol / L sulfuric acid, and the stirring is continued for 1 h, so that the hydroxyl and carboxyl active groups are introduced on the surface of the zinc oxide, the site for subsequent grafting reaction is provided, the surface hydrophilicity is improved, and the dispersion is facilitated; after the reaction, the precipitation is collected by centrifugation at 4000 r / min for 15 min, the precipitation is washed with deionized water until the pH of the filtrate is 7, and the first modified nano zinc oxide is obtained by drying at 50°C for 6 h; B2, a mixed solution D containing styrene, maleic anhydride and sulfobetaine in a dispersed state is configured, water is used as the solvent, and the first modified nano zinc oxide is added; after ultrasonic dispersion for 30 min, the temperature is increased to 75°C, ammonium persulfate is added in four times with an interval of 45 min, the stirring is performed at 300 r / min for 4 h, after the reaction, the suspension is dried by microwave at a power of 600 W and a temperature of 80°C for 10 min, and the stirring is performed every 2 min, so that the second modified nano zinc oxide is obtained, the nano zinc oxide balances the hydrophilicity and hydrophobicity by using the hydrophobic monomer styrene and the polar monomer maleic anhydride, the dispersibility of the zinc oxide in the organic matrix is improved, the compatibility with the resin is enhanced by the styrene segment, and the mechanical properties are improved; B3, the second modified nano zinc oxide is added into a 3% ethylenediaminetetraacetic acid disodium solution, stirred at 50°C and 200 r / min for 3 h, after the stirring, the pH is adjusted to 8.0 by using 1 mol / L sodium hydroxide, the stirring is continued for 1 h, and then the standing is performed for 30 min, so that the interface bonding force between the zinc oxide and the matrix is enhanced, and the heat resistance and the ultraviolet aging resistance of the material are improved; after the reaction, the precipitation is collected by centrifugation at 4000 r / min for 20 min, the precipitation is washed with deionized water for two times, and the modified nano zinc oxide is obtained by air drying at 70°C for 5 h.

[0016] Further, the B1 in the nano zinc oxide, potassium persulfate solution dosage ratio is 50g: 300ml.

[0017] Further, the B2 in the mixed solution D, the first modified nano zinc oxide, the dosage ratio of ammonium persulfate is 250ml: 35g: 0.125g; the mass fraction of styrene, maleic anhydride, sulfobetaine in mixed solution D is 7%, 2%, 1% respectively, the mass fraction is based on the total mass of mixed solution D.

[0018] Further, the B3 in the second modified nano zinc oxide, the dosage ratio of ethylenediaminetetraacetic acid disodium solution is 30g: 200ml.

[0019] A preparation method of a low dielectric constant polyamide material, specifically comprising the following steps: S1, polyamide 66, polytetrafluoroethylene powder, polyether ether ketone, fluorine rubber are added into a high-speed mixer, the temperature in the mixer is controlled at 80-100℃, and mixed at a speed of 800-1000r / min for 3-5min, during which the mixer top cover stirring paddle is scraped once every 2min to ensure uniform mixing of the materials, and a premix is obtained; S2, start the double screw extruder, set the temperature of each zone, and set the vacuum degree to 0.09MPa after the temperature of each zone is stable, and keep idling for 5min; start the main feeding screw, and convey the premix at a feeding rate of 20-25kg / h, and simultaneously adjust the double screw speed to 300-400r / min to match the screw speed with the main feeding rate; simultaneously open the side feeding port, and add modified porous siloxane microspheres, modified nano zinc oxide, glass fiber, graphene nanosheet at a rate of 14-18kg / h, and adjust the side feeding screw speed to 100-130r / min to ensure that the materials are mixed in proportion; titanium ester coupling agent, antioxidant 1010, ethylene bis-stearamide, and ultraviolet absorber UV-531 are injected into the cylinder through a liquid feeding pump, and the liquid feeding rate is controlled at 0.5-1.0L / h to ensure uniform dispersion of the additives; the main feeding, side feeding and liquid pump are added separately to avoid agglomeration caused by direct contact between solid fillers and liquid additives; the residence time of the material in the cylinder is 3-5min, and after melting, shearing and mixing, it is extruded from the die head; S3, the extruded material is first cooled in a water cooling tank, the water temperature in the water cooling tank is controlled at 20-30 DEG C, the material is soaked in water for 10-15 s, to ensure that the material is fully cooled and shaped, while avoiding surface cracking of the particles caused by long-term cooling; the cooled material is pulled to a pelletizer, and the material is cut into particles with a particle size of 2-3 mm; the pelletized particles are dried at 80-100 DEG C, hot air speed 1.5-2.0 m / s for 4-6 h, to quickly remove the surface moisture of the particles, to avoid bubbles caused by moisture in the injection molding process, to obtain a low dielectric constant polyamide material.

[0020] Further, the temperature of each zone in S2 is set: zone 1 230-240 DEG C, zone 2 240-250 DEG C, zone 3 250-260 DEG C, zone 4 250-260 DEG C, zone 5 240-250 DEG C, and the head temperature 230-240 DEG C.

[0021] The application provides a low dielectric constant polyamide material, which has the following beneficial effects: 1, the material is compounded by polytetrafluoroethylene micro powder, modified porous siloxane microspheres and other components with low dielectric properties, and the compatibility of each component and the polyamide matrix is improved by the aid of titanate coupling agent, so that the dielectric performance fluctuation caused by uneven component dispersion is avoided. The synergistic effect makes the overall dielectric constant of the material effectively reduced, and the stability of the dielectric performance can be maintained in a high-frequency environment, which can stably adapt to 5G communication, high-frequency integrated circuit and other scenes with strict requirements for low dielectric materials, and provides a reliable material basis for the rapid transmission of electronic device signals.

[0022] 2, relying on the skeleton support effect of glass fiber and the two-dimensional reinforcing effect of graphene nanosheet, combined with the precise proportioning of each component, the material can maintain the toughness of polyamide itself while significantly improving the overall tensile strength, bending strength and impact resistance. At the same time, the modified porous siloxane microspheres, nano zinc oxide and other particles are closely combined with the matrix interface, avoiding the problem of increased material brittleness caused by traditional filler addition, so that the material can not only bear the static load of the structure, but also cope with the dynamic impact in the use process, adapting to the mechanical requirements in various working conditions.

[0023] 3, the addition of antioxidant 1010 in the formula can effectively inhibit the oxidative degradation of the material in high temperature or long-term use process, delay the aging of molecular chain; ultraviolet absorber UV-531 can absorb ultraviolet energy and convert it into harmless heat energy, reducing the damage of ultraviolet radiation to the material structure; the introduction of fluoro rubber enhances the resistance of the material to acid, alkali, organic solvent and other chemical media. The synergistic effect of various functional additives makes the material still maintain stable physical and chemical properties in complex environments such as high and low temperature alternation, humidity and strong light, greatly prolonging the service life.

[0024] 4. The material components are premixed and evenly dispersed in a high-speed mixer. In a twin-screw extruder, precise control of temperature, screw speed, and feed rate in each zone achieves efficient synergy in melting, shearing, and mixing, ensuring that the material is fully plasticized within the barrel without excessive degradation. The pellets, after cooling and pelletizing, have a uniform particle size and excellent fluidity, making them suitable for low-pressure injection molding processes with pressures below 5 MPa. They can be processed into various complex shapes without additional process adjustments, and are less susceptible to defects such as warping and cracking during the molding process, making them suitable for large-scale industrial production applications. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] Example 1: Preparation of low dielectric constant polyamide material. The specific preparation steps are as follows: S1. Add 35 parts of polyamide 66, 5 parts of polytetrafluoroethylene powder, 4 parts of polyetheretherketone, and 3 parts of fluororubber into a high-speed mixer, control the temperature in the mixer to 80°C, and mix at a speed of 800 r / min for 3 minutes. During this period, open the top cover of the mixer and scrape the wall with a stirring paddle every 2 minutes to ensure that the materials are evenly mixed to obtain a premix; S2. Start the twin-screw extruder and set the temperature of each zone: zone 1 230℃, zone 2 240℃, zone 3 250℃, zone 4 250℃, zone 5 240℃, and die head temperature 230℃. After the temperature of each zone stabilizes, set the vacuum degree to 0.09MPa and keep running at no-load for 5min. Start the main feeding screw and deliver the premix at a feeding rate of 20kg / h. Simultaneously adjust the twin-screw speed to 300r / min to match the screw speed with the main feeding rate. Simultaneously open the side feeding port and feed 8 parts of modified porous siloxane microspheres and 3 parts of modified Nano zinc oxide, 10 parts of glass fiber, and 1 part of graphene nanosheets were added at a rate of 14 kg / h, and the side feeding screw speed was adjusted to 100 r / min to ensure that the materials were mixed in proportion. 1 part of titanate coupling agent, 0.3 parts of antioxidant 1010, 0.5 parts of ethylene bisstearamide, and 0.1 parts of ultraviolet absorber UV-531 were injected into the barrel through a liquid feeding pump, and the liquid feeding rate was controlled at 0.5 L / h to ensure that the additives were evenly dispersed. The material stayed in the barrel for 3 minutes and was extruded from the die after melting, shearing, and mixing. S3, the extruded material is first cooled in a water cooling tank, the water temperature in the water cooling tank is controlled at 20℃, the material is soaked in water for 10s to ensure that the material is fully cooled and shaped; the cooled material is pulled to a granulator, the material is cut into particles with a particle size of 2mm; the cut particles are dried at 80℃, hot air speed 1.5m / s for 4h to obtain a low dielectric constant polyamide material.

[0027] Example 2, preparation of a low dielectric constant polyamide material, the specific preparation steps are as follows: S1, 45 parts of polyamide 66, 10 parts of polytetrafluoroethylene powder, 8 parts of polyether ether ketone, 5 parts of fluororubber are added into a high-speed mixer, the temperature in the mixer is controlled at 100℃, and mixed at a speed of 1000r / min for 5min, and the mixing paddle on the top cover is scraped once every 2min during the mixing to ensure uniform mixing of the material, and a premix is obtained; S2, start the double screw extruder, set the temperature of each zone: zone 1 240℃, zone 2 250℃, zone 3 260℃, zone 4 260℃, zone 5 250℃, die temperature 240℃, after the temperature in each zone is stable, set the vacuum degree to 0.09MPa, and keep idle running for 5min; start the main feeding screw, convey the premix at a feeding rate of 25kg / h, synchronously adjust the double screw speed to 400r / min, so that the screw speed matches the main feeding rate; synchronously open the side feeding port, add 12 parts of modified porous siloxane microspheres, 7 parts of modified nano zinc oxide, 15 parts of glass fiber, and 3 parts of graphene nanosheet at a rate of 18kg / h, adjust the side feeding screw speed to 130r / min to ensure that the materials are mixed in proportion; 2 parts of titanate coupling agent, 0.7 parts of antioxidant 1010, 1.0 parts of ethylene bis-stearamide, and 0.3 parts of ultraviolet absorber UV-531 are injected into the cylinder through a liquid feeding pump, and the liquid feeding rate is controlled at 1.0L / h to ensure uniform dispersion of the additives; the material stays in the cylinder for 5min, and is extruded from the die after melting, shearing and mixing; S3, the extruded material is first cooled in a water cooling tank, the water temperature in the water cooling tank is controlled at 30℃, the material is soaked in water for 15s to ensure that the material is fully cooled and shaped; the cooled material is pulled to a granulator, the material is cut into particles with a particle size of 3mm; the cut particles are dried at 100℃, hot air speed 2.0m / s for 6h to obtain a low dielectric constant polyamide material.

[0028] Example 3, preparation of a low dielectric constant polyamide material, the specific preparation steps are as follows: S1. Add 40 parts of polyamide 66, 7 parts of polytetrafluoroethylene powder, 6 parts of polyetheretherketone, and 4 parts of fluororubber into a high-speed mixer, control the temperature in the mixer to 90°C, and mix at a speed of 900 r / min for 4 minutes. During this period, open the top cover of the mixer and scrape the wall with a stirring paddle every 2 minutes to ensure that the materials are evenly mixed to obtain a premix; S2. Start the twin-screw extruder and set the temperature of each zone: zone 1 235℃, zone 2 245℃, zone 3 255℃, zone 4 255℃, zone 5 245℃, and die head temperature 235℃. After the temperature of each zone stabilizes, set the vacuum degree to 0.09MPa and keep running at no load for 5 minutes. Start the main feeding screw and deliver the premix at a feeding rate of 22kg / h. Simultaneously adjust the twin-screw speed to 350r / min to match the screw speed with the main feeding rate. Simultaneously open the side feeding port and feed 10 parts of modified porous siloxane microspheres and 5 parts of modified Nano zinc oxide, 12 parts of glass fiber, and 2 parts of graphene nanosheets were added at a rate of 16 kg / h, and the side feeding screw speed was adjusted to 115 r / min to ensure that the materials were mixed in proportion. 1 part of titanate coupling agent, 0.5 part of antioxidant 1010, 0.7 part of ethylene bisstearamide, and 0.2 part of ultraviolet absorber UV-531 were injected into the barrel through a liquid feeding pump. The liquid feeding rate was controlled at 0.7 L / h to ensure that the additives were evenly dispersed. The material stayed in the barrel for 4 minutes and was extruded from the die after melting, shearing, and mixing. S3. The extruded material is first cooled in a water cooling tank. The water temperature in the water cooling tank is controlled at 25°C. The material is immersed in water for 12 seconds to ensure that the material is fully cooled and shaped. The cooled material is pulled to a pelletizer and cut into pellets with a particle size of 2 mm. The pelletized pellets are dried at 90°C and a hot air speed of 2.0 m / s for 5 hours to obtain a low dielectric constant polyamide material.

[0029] Example 4: Preparation of modified porous siloxane microspheres. The specific preparation steps are as follows: A1. Add 80 g of porous silicone microspheres with a pore size of 15 nm to 400 mL of a mixed solution A prepared by a volume ratio of 2:1 of 8% ammonium fluoride solution and 5% hydrochloric acid solution. Stir at 200 r / min for 50 min at 25°C, then heat to 40°C at a rate of 1°C / min and continue stirring for 30 min. Samples are taken every 15 min to detect the pore size using a laser particle size analyzer, and the final pore size is controlled to be 25-30 nm. After the reaction, wash with deionized water until the pH of the filtrate reaches 7.0, then add deionized water and ultrasonicate for 20 min to form a uniform suspension. The suspension is centrifuged at 3000 r / min for 15 min, the supernatant is poured out, and the precipitate is dried in a vacuum at 60°C and -0.09 MPa for 5 h to obtain the first modified microspheres. A2, configuration 600 mL containing 6%tridecafluoroalkyl triethoxysilane, 2% methacryloxypropyl trimethoxysilane, 0.2% p-toluene sulfonic acid mixed solution B, solvent is cyclohexane, to the mixed solution, 60 g of the first modified microspheres, nitrogen protection, heated to 80 DEG C, three times the total amount of 0.9 g of azobisisobutyronitrile, each interval 30 min, 300 r / min stirring 5 h; after the reaction, first hot with Buchner funnel filtration to collect microspheres, filter cake with cyclohexane rinse 2 times, then the microspheres are transferred to a beaker, add cyclohexane, in 80 DEG C constant temperature water bath stirring 3 times, 30 min each time, and change the new cyclohexane, finally at 70 DEG C air drying 4 h; A3, take 40 g of the second modified microspheres are added to 400 mL containing 5% divinyl benzene, 0.3% benzophenone mixed solution C, solvent is anhydrous ethanol, ultrasonic dispersion 20 min to form a uniform suspension, the dispersed system is transferred to the ultraviolet light reaction kettle, nitrogen protection, wavelength 365 nm, power 200 W irradiation 1 h, every 15 min stirring once, after 4000 r / min centrifugation 20 min, collect the microspheres, washed with anhydrous ethanol 2 times, 80 DEG C, -0.09 MPa vacuum drying 6 h, to obtain modified porous siloxane microspheres.

[0030] Example 5, preparation of modified nano zinc oxide, the specific preparation steps are as follows: B1, 50 g of nano zinc oxide is added to 300 mL of 8% potassium persulfate solution, 60 DEG C with 250 r / min stirring 2 h, during every 30 min with 30 mL / min flow of oxygen 10 min, after adjusting the pH to 3.0 with 1 mol / L sulfuric acid, continue to stir 1 h, after the reaction, 4000 r / min centrifugation 15 min, collect the precipitate, washed with deionized water until the filtrate pH is 7, then 50 DEG C drying 6 h, to obtain the first modified nano zinc oxide; B2, configuration 250 mL containing 7% dispersion state of styrene, 2% maleic anhydride, 1% sulfobetaine mixed solution D, solvent is water, 35 g of the first modified nano zinc oxide is added; after ultrasonic dispersion for 30 min, heated to 75 DEG C, four times the total amount of 0.125 g of ammonium persulfate, each interval 45 min, 300 r / min stirring 4 h, after the reaction, the suspension is dried under microwave power 600 W, temperature 80 DEG C for 10 min, every 2 min stirring once, to obtain the second modified nano zinc oxide; B3, 30 g of the second modified nano-zinc oxide was added into 200 mL of 3% ethylenediaminetetraacetic acid disodium solution, and stirred at 200 r / min for 3 h at 50℃, then 1 mol / L sodium hydroxide was used to adjust the pH to 8.0, and stirred for another 1 h, and then placed for 30 min, and then centrifuged at 4000 r / min for 20 min, and then the precipitate was collected, washed with deionized water for 2 times, and then dried at 70℃ with air blowing for 5 h to obtain the modified nano-zinc oxide.

[0031] Comparative Example 1, a low dielectric constant polyamide material was prepared, and the specific preparation steps were as follows: The remaining steps were unchanged, only the modified porous siloxane microspheres of Example 3 were replaced with porous siloxane microspheres without any treatment, and a low dielectric constant polyamide material was prepared.

[0032] Comparative Example 2, a low dielectric constant polyamide material was prepared, and the specific preparation steps were as follows: The remaining steps were unchanged, only the modified nano-zinc oxide of Example 3 was replaced with nano-zinc oxide without any treatment, and a low dielectric constant polyamide material was prepared.

[0033] Performance test

[0034] According to the performance test results, the low dielectric constant polyamide materials of Examples 1-3 were superior to Comparative Examples 1-2 in dielectric properties (dielectric constant 2.1-2.3, dielectric loss 0.0028-0.0035), melt index (35-40 g / 10 min), tensile strength (85-90 MPa), impact strength (24-27 kJ / m 2 ), heat distortion temperature (220-230℃), and tensile strength retention rate after ultraviolet aging (92-95%), and the performance of Example 3 was the best; the performance of Comparative Example 1 using untreated porous siloxane microspheres and Comparative Example 2 using untreated nano-zinc oxide all decreased, indicating that the modified porous siloxane microspheres and the modified nano-zinc oxide played a key role in improving the performance of the material.

[0035] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as they do not deviate from the invention or exceed the scope defined by the present claims, and should belong to the protection scope of the present application.

Claims

1. A low dielectric constant polyamide material, characterized by: The invention comprises the following raw materials in parts by weight: 35-45 parts of polyamide 66, 5-10 parts of polytetrafluoroethylene powder, 8-12 parts of modified porous silicone microspheres, 3-7 parts of modified nano zinc oxide, 10-15 parts of glass fiber, 4-8 parts of polyetheretherketone, 1-3 parts of graphene nanosheets, 3-5 parts of fluororubber, 1-2 parts of titanate coupling agent, 0.3-0.7 parts of antioxidant 1010, 0.5-1.0 parts of ethylene bisstearamide, and 0.1-0.3 parts of ultraviolet absorber UV-531.

2. The low dielectric constant polyamide material according to claim 1, characterized in that: The polytetrafluoroethylene micropowder has a particle size of 1-5 μm, and its surface is pretreated with a silane coupling agent KH-550. The pretreatment method is as follows: the polytetrafluoroethylene micropowder is added to a 3% by mass silane coupling agent KH-550 ethanol solution, ultrasonically dispersed for 15 minutes, stirred and reacted at 60° C. for 2 hours, filtered, and vacuum dried at 80° C. for 3 hours to obtain surface-modified polytetrafluoroethylene micropowder.

3. The low dielectric constant polyamide material according to claim 1, characterized in that: The glass fiber is an alkali-free glass fiber with an aspect ratio of 10-20 and is treated with a silane coupling agent KH-550. The treatment process is as follows: adding the glass fiber to an aqueous solution containing 2% silane coupling agent KH-550, stirring at 50° C. for 30 minutes, filtering, drying at 110° C. for 2 hours, and cooling for standby use.

4. The low dielectric constant polyamide material according to claim 1, characterized in that: The graphene nanosheets are single-layer graphene with a thickness of ≤5 nm and a lateral size of 1-5 μm, and their surfaces are modified with hexadecyltrimethylammonium bromide. The modification method is as follows: the graphene nanosheets are added to a 0.5% hexadecyltrimethylammonium bromide aqueous solution, ultrasonically treated for 30 minutes, centrifuged at 7000 r / min for 15 minutes, washed with deionized water until no bromide ions are detected, and vacuum dried at 60° C. for 4 hours.

5. The low dielectric constant polyamide material according to claim 1, characterized in that: The modified porous siloxane microspheres are specifically prepared in the following steps: A1. Porous silicone microspheres with a pore size of 15 nm were added to a mixed solution A prepared by a volume ratio of 2:1 of 8% ammonium fluoride solution and 5% hydrochloric acid solution. The mixture was stirred at 200 r / min at 25°C for 50 min, then heated to 40°C at a rate of 1°C / min and stirred for 30 min. Samples were taken every 15 min to detect the pore size using a laser particle size analyzer, and the final pore size was controlled to be 25-30 nm. After the reaction, the filtrate was washed with deionized water until the pH of the filtrate reached 7, and then added to deionized water and ultrasonicated for 20 min to form a uniform suspension. The suspension was centrifuged at 3000 r / min for 15 min, the supernatant was poured out, and the precipitate was dried in a vacuum at 60°C and -0.09 MPa for 5 h to obtain the first modified microspheres. A2. Prepare a mixed solution B containing tridecafluorooctyl triethoxysilane, methacryloyloxypropyl trimethoxysilane, and p-toluenesulfonic acid. The solvent is cyclohexane. Add the first modified microspheres to the mixed solution, heat to 80°C under nitrogen protection, add azobisisobutyronitrile three times, each with an interval of 30 minutes, and stir at 300 r / min for 5 hours. After the reaction is completed, collect the microspheres with suction filtration using a Buchner funnel while still hot, rinse the filter cake twice with cyclohexane, transfer the microspheres to a beaker, add cyclohexane, and stir and wash in a constant temperature water bath at 80°C for three times, each time for 30 minutes. Replace with new cyclohexane, and finally dry at 70°C with air for 4 hours. A3. Take the second modified microspheres and add them into the mixed solution C containing divinylbenzene and benzophenone. The solvent is anhydrous ethanol. Ultrasonic dispersion is carried out for 20 minutes to form a uniform suspension. The dispersed system is transferred to an ultraviolet reactor. Under nitrogen protection, the wavelength is 365nm and the power is 200W. Irradiate for 1 hour. Stir once every 15 minutes. After the end, centrifuge at 4000r / min for 20 minutes. Collect the microspheres, wash them twice with anhydrous ethanol, and vacuum dry them at 80℃ and -0.09MPa for 6 hours to obtain modified porous silicone microspheres.

6. The low dielectric constant polyamide material according to claim 5, characterized in that: The ratio of the porous silicone microspheres to the mixed solution A in A1 is 80 g:400 mL. If the pore size is only expanded to 18-20 nm after 15 minutes, the stirring speed can be increased to 250 rpm. If the pore size exceeds 25 nm after 30 minutes, the temperature rise phase is started in advance. The amount ratio of the mixed solution B, the first modified microspheres, and azobisisobutyronitrile in A2 is 600 mL: 60 g: 0.9 g; the mass fractions of tridecafluorooctyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, and p-toluenesulfonic acid in the mixed solution B are 6%, 2%, and 0.2%, respectively, and the mass fractions are based on the total mass of the mixed solution B; The amount ratio of the second modified microspheres and the mixed solution C in A3 is 40 g:400 mL; the mass fractions of divinylbenzene and benzophenone in the mixed solution C are 5% and 0.3%, respectively, and the mass fractions are based on the total mass of the mixed solution C.

7. The low dielectric constant polyamide material according to claim 1, characterized in that: The modified nano zinc oxide is specifically prepared in the following steps: B1. Add nano zinc oxide to 8% potassium persulfate solution, stir at 250 r / min at 60°C for 2 h, during which oxygen is introduced at a flow rate of 30 mL / min for 10 min every 30 min. After the reaction, adjust the pH to 3.0 with 1 mol / L sulfuric acid and continue stirring for 1 h. After the reaction is completed, centrifuge at 4000 r / min for 15 min, collect the precipitate, wash with deionized water until the pH of the filtrate is 7, and then dry at 50°C for 6 h to obtain the first modified nano zinc oxide; B2. Prepare a mixed solution D containing dispersed styrene, maleic anhydride, and sulfobetaine using water as the solvent, and add the first modified nano-zinc oxide; after ultrasonic dispersion for 30 minutes, raise the temperature to 75°C, add ammonium persulfate four times, each time with an interval of 45 minutes, and stir at 300 rpm for 4 hours. After the reaction is completed, microwave dry the suspension at 600 W power and 80°C for 10 minutes, stirring every 2 minutes, to obtain the second modified nano-zinc oxide; B3. Add the second modified nano zinc oxide into 3% disodium ethylenediaminetetraacetic acid solution, stir at 200 r / min at 50°C for 3 h, adjust the pH to 8.0 with 1 mol / L sodium hydroxide, continue stirring for 1 h and let it stand for 30 min. After the reaction is completed, centrifuge at 4000 r / min for 20 min, collect the precipitate, wash twice with deionized water, and dry with air at 70°C for 5 h to obtain modified nano zinc oxide.

8. The low dielectric constant polyamide material according to claim 7, characterized in that: The dosage ratio of nano zinc oxide and potassium persulfate solution in B1 is 50g:300mL; The ratio of the mixed solution D, the first modified nano zinc oxide, and ammonium persulfate in B2 is 250 mL: 35 g: 0.125 g; the mass fractions of styrene, maleic anhydride, and sulfobetaine in the mixed solution D are 7%, 2%, and 1%, respectively, and the mass fractions are based on the total mass of the mixed solution D; The usage ratio of the second modified nano zinc oxide and disodium ethylenediaminetetraacetic acid solution in B3 is 30g:200mL.

9. A method for preparing a low dielectric constant polyamide material, characterized in that: The specific steps include: S1. Add polyamide 66, polytetrafluoroethylene powder, polyetheretherketone, and fluororubber into a high-speed mixer, control the temperature in the mixer to 80-100°C, and mix at a speed of 800-1000 r / min for 3-5 minutes. During this period, open the mixer cover and scrape the wall with a stirring paddle every 2 minutes to ensure that the materials are evenly mixed to obtain a premix; S2. Start the twin-screw extruder, set the temperature of each zone, and after the temperature of each zone is stable, set the vacuum degree to 0.09 MPa and keep it running at no-load for 5 minutes; start the main feeding screw and deliver the premix at a feeding rate of 20-25 kg / h, and adjust the twin-screw speed to 300-400 r / min to match the screw speed with the main feeding rate; open the side feeding port simultaneously and feed the modified porous siloxane microspheres, modified nano zinc oxide, glass fiber, and graphene nanosheets. Add at a rate of 14-18 kg / h, and adjust the side feeding screw speed to 100-130 r / min to ensure that the materials are mixed in proportion. Titanate coupling agent, antioxidant 1010, ethylene bisstearamide, and UV absorber UV-531 are injected into the barrel through a liquid feeding pump, and the liquid feeding rate is controlled at 0.5-1.0 L / h to ensure that the additives are evenly dispersed. The material stays in the barrel for 3-5 minutes, and after melting, shearing, and mixing, it is extruded from the die head. S3. The extruded material is first cooled in a water cooling tank. The water temperature in the water cooling tank is controlled at 20-30°C. The material is immersed in water for 10-15 seconds to ensure that the material is fully cooled and shaped. The cooled material is pulled to a pelletizer and cut into pellets with a particle size of 2-3 mm. The pelletized pellets are dried at 80-100°C and a hot air speed of 1.5-2.0 m / s for 4-6 hours to obtain a low dielectric constant polyamide material.

10. The method for preparing a low dielectric constant polyamide material according to claim 9, characterized in that: In S2, the temperature of each zone is set as follows: zone 1 230-240°C, zone 2 240-250°C, zone 3 250-260°C, zone 4 250-260°C, zone 5 240-250°C, and the head temperature is 230-240°C.

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