Electromagnetic shielding heat-conducting polyether-ether-ketone composite material with low dielectric constant and preparation method thereof

Abstract

The invention provides a low-dielectric-constant electromagnetic-shielding heat-conducting polyether-ether-ketone composite material and a preparation method thereof, and belongs to the technical field of high polymer material processing, the low-dielectric-constant electromagnetic-shielding heat-conducting polyether-ether-ketone composite material comprises the following raw materials: polyether-ether-ketone resin, low-dielectric-constant glass fibers, a conductive filler, a low-dielectric-constant filler and an auxiliary agent; comprising the following steps: S1, uniformly mixing polyether-ether-ketone resin, a low-dielectric filler, a conductive filler and an auxiliary agent to obtain a mixed material; s2, the mixed material is added into a double-screw extruder from a main feeding port, the low-dielectric glass fiber is added into the double-screw extruder from a side feeding port, the mixed material and the low-dielectric glass fiber are evenly mixed in a screw cavity of the double-screw extruder, and a secondary mixed material is obtained; s3, the secondary mixed material is subjected to heating melting, extrusion granulation and sieving, and the polyether-ether-ketone composite material is obtained. According to the technical scheme provided by the invention, the composite material has the properties of low dielectric constant, strong electromagnetic shielding and high thermal conductivity at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material processing, and in particular to a low-dielectric-constant electromagnetic shielding and heat-conducting polyetheretherketone composite material and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, electronic devices and communications technologies have been widely applied in various fields of society. In today's era of vigorous development of 5G wireless communications, materials have become a major factor limiting the development of 5G technology. On the one hand, 5G's high transmission speed and low signal strength require materials with low dielectric constants. On the other hand, 5G's poor electromagnetic wave coverage requires materials with strong electromagnetic shielding capabilities. Furthermore, the high heat generation of 5G also requires materials with strong thermal conductivity and good heat resistance.

[0003] Polyetheretherketone (PEEK) is a polymer composed of repeating units containing one ketone bond and two ether bonds in its backbone structure. It is a specialty polymer material. Due to its low dielectric constant and metal substitution properties, PEEK is suitable for 5G applications in antenna modules, filters, connectors, and other related components. Patent Publication No. CN113308083A, entitled "A Low Dielectric Constant Polyetheretherketone Composite Material and Its Preparation Method," discloses a low-dielectric-constant polyetheretherketone composite material composed of the following raw materials by weight: 50-80 parts polyetheretherketone resin, 10-30 parts thermotropic liquid crystal polymer, 2-5 parts doped silica, 1-2 parts compatibilizer, 0.5-1 part coupling agent, and 0.5-1 part antioxidant. While this technical solution achieves a low-dielectric-constant polyetheretherketone composite material, it still fails to meet the material's requirements for high thermal conductivity and strong electromagnetic shielding capabilities.

[0004] Therefore, it is necessary to provide a low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material and a preparation method thereof to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0005] In view of this, the present invention provides a low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material and a preparation method thereof, so as to achieve the composite material having the properties of low dielectric constant, strong electromagnetic shielding and high thermal conductivity.

[0006] To achieve the above objectives, the present invention provides a low dielectric constant electromagnetic shielding and thermal conductive polyetheretherketone composite material, which includes the following raw materials: polyetheretherketone resin, low dielectric glass fiber, conductive filler, low dielectric filler and additives.

[0007] Optionally, the polyetheretherketone composite material includes the following raw materials in the following weight percentages: 45-77% polyetheretherketone resin, 10-30% low-dielectric glass fiber, 5-10% conductive filler, 5-10% low-dielectric filler and 3-5% additives.

[0008] Optionally, the polyetheretherketone resin is an aromatic polyetheretherketone resin; and the dielectric constant of the low-dielectric glass fiber is 3 to 5.

[0009] The aromatic polyetheretherketone resin in the present invention has excellent mechanical properties and chemical resistance; high temperature resistance, the long-term use temperature can reach 260°C; its electrical properties are also very good, at room temperature, the dielectric constant is 3.2, and the dielectric loss is 0.02; good processing performance, above the melting point, it has good melt fluidity and thermal stability; hot water resistance and steam resistance, and can be used in a steam environment; flame retardancy, wear resistance, high strength, high rigidity, high heat deformation temperature, small thermal expansion coefficient; dimensional stability, low water absorption and small dimensional change after water absorption, little change in mechanical strength; very small molding shrinkage, suitable for precision molding processing. Using polyetheretherketone resin as the matrix resin can make the composite material inherit the above-mentioned excellent properties and have more application fields.

[0010] The present invention uses low-dielectric glass fiber with a dielectric constant of 3 to 5. While maintaining the original mechanical strength, the dielectric constant and dielectric loss are low. On the one hand, it can enhance the mechanical properties of the resin matrix, and on the other hand, it can avoid causing an increase in the dielectric constant and dielectric loss of the composite material.

[0011] Optionally, the auxiliary agents include a primary antioxidant, a high-temperature resistant secondary antioxidant, an antistatic agent and a lubricant.

[0012] The present invention uses a compound of a primary antioxidant and a high-temperature resistant secondary antioxidant to slow down the thermal oxidation rate of the composite material during processing and use, thereby extending the service life of the composite material; the antistatic agent can suppress the generation of static electricity during the use of the composite material; the lubricant can enhance the compatibility between the matrix resin and the filler, improve the dispersibility of the filler in the matrix resin, and improve the wear resistance.

[0013] Optionally, the conductive filler is one or more of graphite, carbon nanotubes, carbon fibers, graphene and carbon black.

[0014] When electromagnetic waves propagate onto the surface of a shielding material, they are typically attenuated by three different mechanisms: absorption loss from unreflected waves entering the shield; reflection loss from reflecting surfaces; and multiple reflections within the shield. The reflection loss of electromagnetic waves is closely related to the conductivity of the shielding material. The higher the conductivity of the material, the greater the reflection loss and the stronger the shielding effectiveness. Conductive fillers dispersed in the polymer form a conductive network, significantly increasing electromagnetic wave attenuation. Furthermore, the self-lubricating properties of polyetheretherketone resins facilitate the better dispersion of conductive fillers within the matrix resin, forming a well-formed conductive network and improving the conductivity of the composite material. Heat transfer is essentially an energy transfer phenomenon caused by temperature gradients. From a microscopic perspective, phonons are the quantized energy of lattice vibrations. Temperature gradients create concentration differences in phonons. Under the influence of these concentration differences, phonons diffuse, forming a directed diffusion flow. The directed motion of phonons results in directed energy movement, which is heat conduction. However, within the resin matrix, phonons scatter at the interfaces of defects and impurities in the amorphous phase, resulting in poor heat conduction. The above-mentioned conductive filler is also a high thermal conductivity material. The thermal conductive network constructed by the filling of the thermal conductive material can effectively enhance the thermal conductivity of the composite material.

[0015] Optionally, the low dielectric filler is one or more of mica powder, kaolin, boron nitride and silicon carbide.

[0016] The present invention adds low dielectric fillers to the resin matrix, mainly to allow the low dielectric filler molecules to enter the resin matrix molecules, reduce the molecular density, reduce the molecular polarization of the composite material, and thus reduce the dielectric constant of the composite material.

[0017] Optionally, the main antioxidant is N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine; the high-temperature resistant auxiliary antioxidant is bis(2,4-dicumylphenyl)pentaerythritol diphosphite; the antistatic agent is polyquaternary ammonium salt; and the lubricant is polytetrafluoroethylene micropowder wax.

[0018] In this invention, the primary antioxidant contains active hydrogen atoms within its molecules. These hydrogen atoms are more active than those in the molecular chain and can combine with free radicals R• or ROO• released from the decomposed macromolecular chain, 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 generation of more free radicals, thereby maintaining the thermal stability of the organic matter and extending its service life. The primary and secondary antioxidants work synergistically to slow the rate of thermal oxidation of organic matter during processing and use, even before and after processing. When an antistatic agent is added to the resin matrix, it forms an antistatic molecular layer on the surface of the material. If this molecular layer is damaged, the internal antistatic agent penetrates the surface and repairs the damaged molecular layer, thus suppressing static electricity. Polytetrafluoroethylene micropowder wax acts as a lubricant, increasing compatibility and promoting filler dispersion. Its lower dielectric constant also affects the dielectric constant of the composite material.

[0019] To achieve the above object, the present invention also provides a method for preparing a low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material, comprising the following steps: S1, uniformly mixing polyetheretherketone resin, low dielectric filler, conductive filler and additives to obtain a mixed material; S2, adding the mixed material to a twin-screw extruder from a main feeding port, adding the low-dielectric glass fiber to the twin-screw extruder from a side feeding port, and uniformly mixing the mixed material and the low-dielectric glass fiber in the screw cavity of the twin-screw extruder to obtain a secondary mixed material; S3. The secondary mixed material is heated, melted, extruded, granulated, and sieved to obtain a low dielectric constant electromagnetic shielding and thermally conductive polyetheretherketone composite material.

[0020] Optionally, before the polyetheretherketone resin is uniformly mixed with the low dielectric filler, the conductive filler and the additive in S1, the polyetheretherketone resin is dried at a temperature of 150-160° C. and a drying time of 2-4 hours.

[0021] Optionally, the heating and melting temperature is 350-400°C.

[0022] The above technical solution of the present invention includes at least the following beneficial effects: The present invention provides a low dielectric constant electromagnetic shielding and thermal conductive polyetheretherketone composite material, which uses polyetheretherketone resin as a matrix resin and a compound of low dielectric glass fiber, conductive filler and low dielectric filler as filler to enhance the mechanical properties of the matrix resin, improve the electrical conductivity and thermal conductivity coefficient and reduce the dielectric constant. The compatibility between the matrix resin and the filler is enhanced by the auxiliary agent, and the lubricant in the auxiliary agent can further reduce the dielectric constant of the composite material. In addition, the conductive filler brings good heat dissipation capability, and the low dielectric filler and the conductive filler can act as nucleating agents to promote the crystallization of polyetheretherketone resin. Based on this, the present application uses low dielectric filler and conductive filler, compounds low dielectric glass fiber, and blends with polyetheretherketone resin to prepare a low dielectric constant electromagnetic shielding and thermal conductive polyetheretherketone composite material which not only has a low dielectric constant, but also has good electromagnetic shielding capability and thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart for preparing a low dielectric constant electromagnetic shielding and thermally conductive polyetheretherketone composite material in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1 , clearly and completely describing the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments derived by ordinary technicians in this field fall within the scope of protection of the present invention.

[0025] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in the present invention are commercially available or can be obtained by conventional methods. Experimental methods in the following examples, where specific conditions are not specified, are generally determined in accordance with national standards. Where applicable, international standards, conventional conditions, or manufacturer-recommended conditions were used instead.

[0026] Example 1 The following raw materials are taken in weight percentage: 61% polyetheretherketone resin, 20% low dielectric glass fiber, 8% conductive filler - graphene, 7% low dielectric filler - boron nitride, and 4% additives, wherein the additives are N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, polyquaternary ammonium salt and polytetrafluoroethylene micropowder wax.

[0027] The polyetheretherketone resin, low dielectric filler, conductive filler and additive are mixed in a high-speed mixer to obtain a mixed material; The mixed material is added to a twin-screw extruder from a main feeding port, and low-dielectric glass fiber is added to the twin-screw extruder from a side feeding port. The mixed material and the modified glass fiber are uniformly mixed in the screw cavity of the twin-screw extruder to obtain a secondary mixed material; The secondary mixed material is heated and melted in the screw cavity, extruded into granules, and sieved to obtain a low dielectric constant electromagnetic shielding and thermally conductive polyetheretherketone composite material.

[0028] Example 2 The following raw materials are taken in weight percentage: 58% polyetheretherketone resin, 20% low dielectric glass fiber, 8% conductive filler - graphene, 10% low dielectric filler - boron nitride, and 4% additives, wherein the additives are N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, polyquaternary ammonium salt and polytetrafluoroethylene micropowder wax.

[0029] The polyetheretherketone resin, low dielectric filler, conductive filler and additive are mixed in a high-speed mixer to obtain a mixed material; The mixed material is added to a twin-screw extruder from a main feeding port, and low-dielectric glass fiber is added to the twin-screw extruder from a side feeding port. The mixed material and the modified glass fiber are uniformly mixed in the screw cavity of the twin-screw extruder to obtain a secondary mixed material; The secondary mixed material is heated and melted in the screw cavity, extruded into granules, and sieved to obtain a low dielectric constant electromagnetic shielding and thermally conductive polyetheretherketone composite material.

[0030] Example 3 The only difference from Example 2 is the composition of the raw materials, namely, 59% polyetheretherketone resin, 20% low dielectric glass fiber, 10% conductive filler - graphene, 7% low dielectric filler - boron nitride, and 4% additives. The remaining steps are the same as Example 2.

[0031] Comparative Example 1 The only difference from Example 2 is the composition of the raw materials, namely, 68% polyetheretherketone resin, 20% low dielectric glass fiber, 8% conductive filler - graphene, and 4% additives. The remaining steps are the same as Example 2.

[0032] Comparative Example 2 The only difference from Example 2 is the composition of the raw materials, namely, 69% polyetheretherketone resin, 20% low dielectric glass fiber, 7% low dielectric filler - boron nitride, and 4% additives. The remaining steps are the same as Example 2.

[0033] Comparative Example 3 The only difference from Example 2 is the composition of the raw materials, namely, 81% polyetheretherketone resin, 8% conductive filler - graphene, 7% low dielectric filler - boron nitride, and 4% additives. The remaining steps are the same as Example 2.

[0034] The raw materials and performance test results of the low dielectric constant electromagnetic shielding and thermal conductive polyetheretherketone composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are summarized in Table 1: Table 1 Summary of raw materials and performance test results of low dielectric constant electromagnetic shielding and thermal conductive polyetheretherketone composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3

[0035] Combining Table 1 with Examples 1 to 3, it can be seen that as the content of the conductive filler graphene increases, its thermal conductivity is significantly improved, but its dielectric constant increases and its shielding effectiveness decreases. This is because the increase in the graphene content causes uneven dispersion of the graphene, resulting in agglomeration, which leads to weak interfacial interaction and degradation of the conductive performance. With the increase in the low-dielectric filler boron nitride, the dielectric constant has a downward trend, indicating that an increase in the addition amount of the low-dielectric filler will significantly reduce the dielectric constant of the material, but the mechanical properties also show a corresponding decrease. This is because the increase in the low-dielectric filler forms more defects inside the composite material, resulting in a decrease in mechanical properties. Therefore, taking all factors into consideration, the mass fraction of the conductive filler and the low-dielectric filler in the low-dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material of the present application is 5-10%.

[0036] Combining Table 1 with Comparative Examples 1 to 3, it can be seen that the low dielectric constant electromagnetic shielding and thermally conductive polyetheretherketone composite material prepared in Example 2 of the present invention effectively combines low dielectric glass fiber, conductive filler and low dielectric filler. While the mechanical properties of the composite material are enhanced by the low dielectric glass fiber, the effect of the increase in dielectric constant caused by the glass fiber is reduced. The addition of the conductive filler can, on the one hand, construct a conductive network of the composite material, significantly improve the electromagnetic shielding effectiveness of the material, and on the other hand, greatly improve the thermal conductivity of the composite material. Although the low dielectric filler will affect the mechanical properties of the composite material, it can significantly reduce the molecular polarization of the material, thereby reducing the dielectric constant of the composite material, and the introduction of the low dielectric glass fiber can compensate for the weakening of the mechanical properties caused by the filler.

[0037] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material, characterized in that: The polyetheretherketone composite material comprises the following raw materials: polyetheretherketone resin, low-dielectric glass fiber, conductive filler, low-dielectric filler and additives.

2. The low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 1, characterized in that: The polyetheretherketone composite material comprises the following raw materials in weight percentage: 45-77% polyetheretherketone resin, 10-30% low-dielectric glass fiber, 5-10% conductive filler, 5-10% low-dielectric filler and 3-5% additive.

3. The low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 1, characterized in that: The polyetheretherketone resin is an aromatic polyetheretherketone resin; and the dielectric constant of the low-dielectric glass fiber is 3-5.

4. The low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 1, characterized in that: The auxiliary agents include a primary antioxidant, a high temperature resistant auxiliary antioxidant, an antistatic agent and a lubricant.

5. The low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 1, characterized in that: The conductive filler is one or more of graphite, carbon nanotubes, carbon fibers, graphene and carbon black.

6. The low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 1, characterized in that: The low dielectric filler is one or more of mica powder, kaolin, boron nitride and silicon carbide.

7. The low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 4, characterized in that: The main antioxidant is N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine; the high temperature resistant auxiliary antioxidant is bis(2,4-dicumylphenyl) pentaerythritol diphosphite; the antistatic agent is polyquaternary ammonium salt; and the lubricant is polytetrafluoroethylene micropowder wax.

8. A method for preparing the low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, uniformly mixing polyetheretherketone resin, low dielectric filler, conductive filler and additive to obtain a mixed material; S2, adding the mixed material into a twin-screw extruder from a main feed port, adding the low dielectric glass fiber into the twin-screw extruder from a side feed port, and uniformly mixing the mixed material and the low dielectric glass fiber in a screw cavity of the twin-screw extruder to obtain a secondary mixed material; S3. The secondary mixed material is heated, melted, extruded, granulated and sieved to obtain a low dielectric constant electromagnetic shielding and thermally conductive polyetheretherketone composite material.

9. The method for preparing the low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 8, characterized in that: Before the polyetheretherketone resin in S1 is uniformly mixed with the low dielectric filler, the conductive filler and the additive, the polyetheretherketone resin is dried at a temperature of 150-160° C. and a drying time of 2-4 hours.

10. The method for preparing the low dielectric constant electromagnetic shielding thermal conductive polyetheretherketone composite material according to claim 8, characterized in that: The heating and melting temperature is 350-400°C.

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