High-temperature nylon / nylon 66 alloy electromagnetic shielding composite material and preparation method therefor

Abstract

The present invention provides a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material and a preparation method therefor. The raw materials of the composite material comprise: high-temperature nylon, nylon 66, modified glass fibers, modified carbon nanotubes, expanded graphite and an auxiliary agent. The high-temperature nylon and the nylon 66 serve as a matrix resin; the modified glass fibers, the modified carbon nanotubes and the expanded graphite are compounded to serve as a filling agent, so as to enhance the mechanical strength of the matrix resin; and the compatibility between the matrix resin and the filling agent is enhanced by means of the auxiliary agent. The dissipation path of electromagnetic waves is further increased by means of the modified carbon nanotubes, thereby enhancing the interfacial polarization effect; the dispersing capacity of the modified carbon nanotubes in the matrix resin is enhanced by means of the expanded graphite, thereby reducing the surface contact resistance; and the electrically conductive paths and the heat dissipation are increased by means of the modified glass fibers, so as to further improve the electromagnetic wave loss capacity. The high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material prepared in the present application not only has excellent dielectric properties, but also has good heat-conducting properties.

Description

High-temperature nylon / nylon 66 alloy electromagnetic shielding composite material and preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of polymer material processing, and in particular relates to a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material and a preparation method thereof. Background Art

[0002] With the rapid development of electronic information technology, electromagnetic radiation pollution generated by electronic devices has become a serious problem in people's lives. Furthermore, interference and confusion between electromagnetic signals have become a primary challenge in the 5G wireless communication era. The development of high-performance electromagnetic shielding materials that effectively shield high- and low-frequency electromagnetic interference has become a current research hotspot. Currently, research on polymer-based electromagnetic shielding materials is limited, and they still suffer from low electromagnetic shielding performance and poor thermal conductivity.

[0003] Therefore, how to provide a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material and a preparation method thereof is a technical problem that needs to be urgently solved by those skilled in the art.

[0004] Summary of the Invention

[0005] The object of the present invention is to provide a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material and a preparation method thereof, so as to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the first aspect of the present invention provides a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material, the raw materials of the composite material including: high-temperature nylon, nylon 66, modified glass fiber, modified carbon nanotubes, expanded graphite and additives.

[0007] In the first aspect, the raw materials of the composite material include, by mass fraction: 10-30% high-temperature nylon, 40-70% nylon 66, 10-30% modified glass fiber, 3-8% modified carbon nanotubes, 1-5% expanded graphite and 0.5-1.5% additives.

[0008] In the first aspect, the auxiliary agent includes a primary antioxidant, a high-temperature resistant secondary antioxidant, and a high-temperature resistant lubricant.

[0009] In the first aspect, the high-temperature nylon is MXD6; and the viscosity of the nylon 66 is 2.8.

[0010] In the first aspect, the modified glass fiber is a long glass fiber surface-treated with a coupling agent.

[0011] In the first aspect, the modified carbon nanotubes are obtained by adding carbon nanotubes to an anhydrous ethanol solution, performing ultrasonic treatment, and drying to obtain the modified carbon nanotubes.

[0012] In the first aspect, the primary antioxidant includes N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine; the high-temperature resistant secondary antioxidant includes bis(2,4-dicumylphenyl)pentaerythritol diphosphite; and the high-temperature resistant lubricant includes pentaerythritol stearate.

[0013] The second aspect of the present invention provides a method for preparing a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material, which is characterized in that, based on the high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material described in the first aspect, the preparation method includes: premixing high-temperature nylon and nylon 66 in a high-speed mixer to obtain an initial mixture; mixing the initial mixture, modified carbon nanotubes, expanded graphite and additives in a high-speed mixer to obtain a secondary mixture; adding the secondary mixture to a twin-screw extruder from a main feeding port, adding modified glass fiber to the twin-screw extruder from a side feeding port, and uniformly mixing the secondary mixture and the modified glass fiber in the screw cavity of the twin-screw extruder to obtain a tertiary mixture; heating and melting the tertiary mixture in the screw cavity, extruding and granulating, and screening to obtain a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material.

[0014] In the second aspect, before pre-mixing the high-temperature nylon and nylon 66 to obtain the initial mixed material, the method further includes: drying the high-temperature nylon and the nylon 66; the drying temperature is 80-100° C., and the drying time is 2-4 hours.

[0015] In the second aspect, the heating and melting temperature is 250-350°C. Beneficial effects:

[0016] The present invention provides a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material. The raw materials of the composite material include: high-temperature nylon, nylon 66, modified glass fiber, modified carbon nanotubes, expanded graphite and additives. High-temperature nylon and nylon 66 are used as matrix resins, and modified glass fiber, modified carbon nanotubes and expanded graphite are compounded as fillers to enhance the mechanical strength of the matrix resin, and the compatibility between the matrix resin and the filler is enhanced by the additives. In addition, modified carbon nanotubes are used to increase the dissipation path of electromagnetic waves and enhance the interface polarization effect. In response, expanded graphite is used to enhance the dispersion ability of modified carbon nanotubes in the matrix resin, reduce the surface contact resistance, and modified glass fiber is used to increase the conductive path and increase heat dissipation, thereby further improving the electromagnetic wave loss capacity. Based on this, the present application uses a "conductor-insulator" core-shell nano conductive filler with modified nanotubes as the core and expanded graphite as the shell, compounded with modified glass fiber, and blended with high-temperature nylon / nylon 66. The prepared high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material not only has excellent dielectric properties, but also has good thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] FIG1 is a flow chart of a method for preparing a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material of the present application. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are for illustrating the present invention, rather than for limiting the present invention.

[0020] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the event of any conflict, the present specification shall take precedence.

[0021] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained through existing methods.

[0022] The present application provides a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material, the raw materials of which include: high-temperature nylon, nylon 66, modified glass fiber, modified carbon nanotubes, expanded graphite and additives.

[0023] Specifically, the present invention provides a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material. The raw materials of the composite material include: high-temperature nylon, nylon 66, modified glass fiber, modified carbon nanotubes, expanded graphite and additives. High-temperature nylon and nylon 66 are used as matrix resins, and modified glass fiber, modified carbon nanotubes and expanded graphite are compounded as fillers to enhance the mechanical strength of the matrix resin, and the compatibility between the matrix resin and the filler is enhanced by the additives. In addition, modified carbon nanotubes are used to increase the dissipation path of electromagnetic waves and enhance the interface polarization. The invention discloses a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material, which has excellent dielectric properties and good thermal conductivity. The composite material has a "conductor-insulator" core-shell nano-conductive filler with modified nanotubes as the core and expanded graphite as the shell, is compounded with modified glass fiber, and is blended with high-temperature nylon / nylon 66. The composite material has the advantages of good thermal conductivity and good dielectric properties.

[0024] In some possible embodiments, the raw materials of the composite material include, by mass fraction: 10-30% high-temperature nylon, 40-70% nylon 66, 10-30% modified glass fiber, 3-8% modified carbon nanotubes, 1-5% expanded graphite and 0.5-1.5% additives.

[0025] In some possible embodiments, the auxiliary agent includes a primary antioxidant, a high-temperature resistant secondary antioxidant, and a high-temperature resistant lubricant.

[0026] Those skilled in the art will understand that the combination of the primary antioxidant and the high-temperature resistant secondary antioxidant can slow down the thermal oxidation rate of the alloy material during processing and use, thereby extending the service life of the alloy material; the high-temperature resistant lubricant can enhance the compatibility between the matrix resin and the filler, and improve the dispersibility of the filler in the matrix resin.

[0027] In some possible embodiments, the high-temperature nylon is MXD6; and the viscosity of the nylon 66 is 2.8.

[0028] This is due to nylon MXD6's high strength, high rigidity, high heat distortion temperature, and low thermal expansion coefficient. It also offers dimensional stability, low water absorption, minimal dimensional change after water absorption, and minimal change in mechanical strength. It also has minimal molding shrinkage, making it suitable for precision molding. It also boasts excellent coating properties, particularly for surface coating at high temperatures, and excellent barrier properties against gases such as oxygen and carbon dioxide. MXD6's excellent mechanical and thermal properties, combined with its high strength, high modulus, heat resistance, high barrier properties, and excellent retort resistance, enhance its strength when blended with nylon 66 resin as a base resin, making it more suitable for processing and applicable in a wider range of fields.

[0029] In some possible embodiments, the modified glass fiber is a long glass fiber surface-treated with a coupling agent.

[0030] Those skilled in the art will understand that modified glass fiber is a long glass fiber that has been surface-treated with a coupling agent and is coated with a layer of metallic silver. On the one hand, it can increase the conductive path, and on the other hand, it can increase heat dissipation. When added to the alloy material, it can also avoid the "floating fiber" phenomenon on the surface of the alloy material, which leads to a decrease in the mechanical strength of the alloy material.

[0031] In some possible embodiments, the modified carbon nanotubes are obtained by adding carbon nanotubes to an anhydrous ethanol solution, performing ultrasonic treatment, and drying to obtain the modified carbon nanotubes.

[0032] This is because ultrasonic treatment of the carbon nanotubes enhances their dispersion in the resin. The modified carbon nanotubes can be better dispersed in the resin, and their hollow structure increases the dissipation pathways for electromagnetic waves, enhancing the interfacial polarization effect. The multilayered carbon nanotube / expanded graphite structure enhances the composite's polarization effect, increasing the dielectric loss pathways and effectively improving electromagnetic wave dissipation capacity. Silver plating on the modified glass fiber surface increases the conductive pathways, further increasing the dielectric loss pathways, effectively improving electromagnetic wave dissipation capacity and also increasing heat dissipation. In other words, when the modified carbon nanotubes and expanded graphite form a "conductor-insulator" core-shell structure, they facilitate uniform dispersion in the matrix resin and, combined with the modified glass fiber, improve the alloy's dielectric properties, enhancing its electromagnetic shielding effect and thermal conductivity.

[0033] In some possible embodiments, the primary antioxidant includes N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine; the high-temperature resistant secondary antioxidant includes bis(2,4-dicumylphenyl)pentaerythritol diphosphite; and the high-temperature resistant lubricant includes pentaerythritol stearate.

[0034] Those skilled in the art will understand that the primary antioxidant contains active hydrogen atoms within its molecules. These H atoms are more active than those in the higher molecular chains and can combine with the free radicals R· or ROO· released from the decomposed macromolecular chains, thereby disrupting chain growth and acting as an antioxidant. The secondary antioxidant reacts with the hydroperoxides produced by the decomposition of organic matter, preventing the generation of free radicals and, in turn, preventing the continued production of more free radicals, thereby maintaining the thermal stability of the organic matter and extending its service life. Light, heat, and oxygen influence both before and after processing. The synergistic effect of the primary and secondary antioxidants can slow the rate of thermal oxidation of the organic matter during processing and use. Pentaerythritol stearate is used as a lubricant to improve material flowability and demolding speed.

[0035] Based on a general inventive concept, referring to FIG1 , a second aspect of the present invention provides a method for preparing a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material. Based on the high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material described in the first aspect, the preparation method comprises:

[0036] S1: premixing high-temperature nylon and nylon 66 in a high-speed mixer to obtain an initial mixed material;

[0037] S2: mixing the initial mixed material, modified carbon nanotubes, expanded graphite and additives in a high-speed mixer to obtain a secondary mixed material;

[0038] S3: adding the secondary mixed material to a twin-screw extruder from a main feeding port, adding the modified glass fiber to the twin-screw extruder from a side feeding port, and uniformly mixing the secondary mixed material and the modified glass fiber in the screw cavity of the twin-screw extruder to obtain a tertiary mixed material;

[0039] S4 The three mixed materials are heated and melted in the screw cavity, extruded into granules, and sieved to obtain a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material.

[0040] In combination with the second aspect of the present application, before pre-mixing the high-temperature nylon and nylon 66 to obtain the initial mixed material, it also includes: drying the high-temperature nylon and the nylon 66; the drying temperature is 80-100°C, and the drying time is 2-4h.

[0041] In combination with the second aspect of the present application, the heating and melting temperature is 250-350°C.

[0042] Specifically, when preparing high-temperature nylon / nylon 66 alloy electromagnetic shielding composite materials, the matrix resin high-temperature nylon and nylon 66 are first dried separately and mixed evenly in a high-speed mixer, and modified carbon nanotubes, expanded graphite and additives are added thereto, wherein the modified carbon nanotubes and expanded graphite form core-shell conductive fillers, which can enhance the dielectric properties of the composite material, increase the dielectric loss path, and effectively improve the electromagnetic wave loss capacity; then the obtained mixture is added to the twin-screw extruder from the main feeding port, and the modified glass fiber is added to the twin-screw extruder from the other side feeding port. The raw materials are mixed evenly by heating and melting in the screw cavity, and are made into strips by cooling. After removing water, they are pelletized and sieved to obtain a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material with uniform particle size, which is finally packaged and sold.

[0043] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0044] The raw material compositions and test results of the high-temperature nylon / nylon 66 alloy electromagnetic shielding composite materials in Examples 1-3 and Comparative Examples 1-3 are shown in the table:

[0045] Table 1 Experimental data

[0046] It can be seen from the above table that: comparing the experimental data of Examples 1-3, as the content of modified glass fiber increases, the electromagnetic shielding performance and thermal conductivity increase. This is because the silver plating on the surface of the modified glass fiber increases the conductive path, increases the dielectric loss path, effectively improves the electromagnetic wave loss capacity, and also increases heat dissipation; however, when the modified glass fiber content is higher, the electromagnetic shielding effectiveness decreases, which may be because too much modified glass fiber reduces the dispersion of carbon nanotubes, weakens the electromagnetic wave dissipation and interface polarization effect. Therefore, the high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material of the present application needs to control the mass fraction of the modified glass fiber to 10-30%.

[0047] Furthermore, compared with Comparative Examples 1-3, the high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material prepared in Example 2 of the present invention effectively uses modified glass fiber, modified carbon nanotubes and expanded graphite. By surface modifying the carbon nanotubes, the dispersion of the carbon nanotubes is improved, and the absorption loss and multiple reflection attenuation are improved; the expanded graphite has a larger surface area, and the functional groups and defects contained on its surface can increase the polarization loss of electromagnetic waves; the silver plating on the surface of the modified glass fiber increases the conductive path, increases the conductive path, significantly increases the conductivity, exerts a synergistic effect, increases the dielectric loss path, further effectively improves the electromagnetic wave loss capacity, and also increases heat dissipation, effectively improving the electromagnetic wave loss capacity of the PPA / PA66 alloy electromagnetic shielding composite material.

[0048] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0050] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A high temperature nylon / nylon 66 alloy electromagnetic shielding composite material, characterized in that: The raw materials of the composite material include: high-temperature nylon, nylon 66, modified glass fiber, modified carbon nanotube, expanded graphite and additives.

2. The high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 1, characterized in that: The raw materials of the composite material include, by mass fraction, 10-30% of high-temperature nylon, 40-70% of nylon 66, 10-30% of modified glass fiber, 3-8% of modified carbon nanotube, 1-5% of expanded graphite and 0.5-1.5% of auxiliary agent.

3. The high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 2, characterized in that: The auxiliary agent includes a main antioxidant, a high temperature resistant auxiliary antioxidant and a high temperature resistant lubricant.

4. The high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 3, characterized in that: The high temperature nylon is MXD6; the viscosity of the nylon 66 is 2.

8.

5. The high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 4, characterized in that: The modified glass fiber is a long glass fiber surface-treated with a coupling agent.

6. The high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 5, characterized in that: The modified carbon nanotubes are obtained by the following method: adding carbon nanotubes into an anhydrous ethanol solution, ultrasonically treating, and drying to obtain the modified carbon nanotubes.

7. The high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 6, characterized in that: The primary antioxidant includes N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine; The high temperature resistant auxiliary antioxidant includes bis(2,4-dicumylphenyl)pentaerythritol diphosphite; The high temperature resistant lubricant includes pentaerythritol stearate.

8. A method for preparing a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material, characterized in that: Based on the high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to any one of claims 1 to 7, the preparation method comprises: Premixing high temperature nylon and nylon 66 in a high-speed mixer to obtain an initial mixed material; The initial mixed material, modified carbon nanotubes, expanded graphite and additives are mixed in the high-speed mixer to obtain a secondary mixed material; The secondary mixed material is added into a twin-screw extruder from a main feed port, and the modified glass fiber is added into the twin-screw extruder from a side feed port, and the secondary mixed material and the modified glass fiber are evenly mixed in the screw cavity of the twin-screw extruder to obtain a tertiary mixed material; The tertiary mixed materials are heated and melted in the screw cavity, extruded into granules, and sieved to obtain a high-temperature nylon / nylon 66 alloy electromagnetic shielding composite material.

9. The method for preparing the high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 8, characterized in that: Before premixing the high temperature nylon and nylon 66 to obtain the initial mixed material, the method further comprises: The high temperature nylon and the nylon 66 are dried; the drying temperature is 80-100° C., and the drying time is 2-4 hours.

10. The method for preparing the high temperature nylon / nylon 66 alloy electromagnetic shielding composite material according to claim 9, characterized in that: The heating and melting temperature is 250-350°C.

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