Preparation method of broadband heat-conducting and wave-absorbing gasket and broadband heat-conducting and wave-absorbing gasket

Abstract

The invention discloses a preparation method of a broadband heat-conducting and wave-absorbing gasket and the broadband heat-conducting and wave-absorbing gasket, and relates to the technical field of wave-absorbing materials. The preparation method of the broadband heat-conducting wave-absorbing gasket comprises the following steps: S300, adding pretreated Fe-Si-Al powder into a reaction system of polypyrrole under the protection of nitrogen, and continuously stirring until polypyrrole forms a coating layer on the surface of the pretreated Fe-Si-Al powder; s400, after the reaction in the step S300 is finished, separating a reaction mixture in the step S300 to obtain polypyrrole coated Fe-Si-Al powder, and washing and drying the polypyrrole coated Fe-Si-Al powder; and S500, mixing the dried polypyrrole coated Fe-Si-Al powder with a polymer matrix material, a heat-conducting filler, a curing agent, a dispersing agent, an inhibitor and a catalyst to obtain a mixture, pressing the mixture into sheets, and curing the sheets to obtain the broadband heat-conducting wave-absorbing gasket. By the adoption of the technical scheme, the advantages of being capable of effectively absorbing electromagnetic waves in a broadband and good in heat conduction performance are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of absorbing materials, and in particular to a preparation method of a broadband heat-conducting wave-absorbing gasket and the broadband heat-conducting wave-absorbing gasket. Background Art

[0002] As electronic devices move toward miniaturization, higher frequencies, and higher power, electromagnetic interference (EMI) and thermal management issues are becoming increasingly prominent, becoming critical issues that require urgent resolution and hinder the performance improvement of electronic devices. While current thermally conductive and absorbing materials offer both thermal conductivity and electromagnetic absorption, they are typically effective within specific frequency bands and struggle to absorb electromagnetic waves across a wider frequency range. This inability to absorb electromagnetic waves of varying frequencies reduces the stability of electronic devices and impacts their service life. Summary of the Invention

[0003] The purpose of the present invention is to address the defects and shortcomings of the existing technology and provide a method for preparing a broadband thermally conductive wave absorbing gasket and a broadband thermally conductive wave absorbing gasket, which have the advantages of being able to effectively absorb electromagnetic waves in a wider frequency range and having good thermal conductivity.

[0004] To achieve the above object, the present invention adopts a technical solution: a method for preparing a broadband heat-conducting and wave-absorbing gasket, comprising the following steps: S300, under nitrogen protection, adding the pretreated Sendust powder to the polypyrrole reaction system, and continuously stirring until the polypyrrole forms a coating layer on the surface of the pretreated Sendust powder; S400, after the reaction in step S300 is completed, separating the reaction mixture in step S300 to obtain polypyrrole-coated sendust powder, and washing and drying the polypyrrole-coated sendust powder; S500, mixing the dried polypyrrole-coated sendust powder with a polymer matrix material, a thermal conductive filler, a curing agent, a dispersant, an inhibitor, and a catalyst to obtain a mixture, pressing the mixture into a sheet, and curing the sheet to obtain a broadband thermal conductive wave absorbing gasket.

[0005] The present invention is further configured to include the following steps before step S300: S200, adding pyrrole monomer and solvent into the reaction device and stirring, adding initiator after stirring evenly, and continuing stirring, reacting at a reaction temperature of 50° C.-60° C. for 3-5 hours to obtain the polypyrrole reaction system.

[0006] The present invention is further configured to include the following steps before step S200: S100, performing preliminary treatment on the sendust powder to increase the surface roughness, ultrasonically dispersing the preliminarily treated sendust powder in a solution for 10 minutes, adding a coupling agent, stirring and reacting at 25° C. for 30 minutes, and then centrifuging and drying to obtain the pretreated sendust powder.

[0007] To achieve the above object, another technical solution adopted by the present invention is: a broadband heat-conducting and wave-absorbing gasket, which is prepared by the broadband heat-conducting and wave-absorbing gasket preparation method described above.

[0008] The present invention further provides that the broadband heat-conducting and wave-absorbing gasket includes the following components in mass fractions: Functional filler: 50%-90%; The functional filler comprises: a sendust base and a polypyrrole layer coated on the surface of the sendust base; the particle size of the sendust base is set to 10-50 μm.

[0009] The present invention further provides that the broadband heat-conducting and wave-absorbing gasket further includes the following components by mass fraction: Polymer matrix material: 3%-10%; thermal conductive filler: 10%-40%; curing agent: 1%-5%; dispersant: 0.1%-1%; coupling agent: 0.1%-1%; inhibitor: 0.01%-0.02%; and catalyst: 0.1%-0.3%.

[0010] The present invention further provides that the polymer matrix material is any one of epoxy resin, silicone rubber, and vinyl silicone oil.

[0011] The present invention further provides that the thermally conductive filler is any one or more of aluminum oxide, aluminum nitride, boron nitride or diamond.

[0012] The present invention further provides that the thermally conductive filler is provided as spherical powder.

[0013] The present invention further provides that the curing agent is 0.12% hydrogen-containing silicone oil.

[0014] By adopting the above technical solution, the present invention has the following beneficial effects: In the present invention, polypyrrole is coated on sendust powder, which increases the dielectric loss of the sendust powder without sacrificing hysteresis loss, effectively widening the absorption bandwidth. The polypyrrole-coated sendust powder is simultaneously mixed with a polymer matrix material, a thermally conductive filler, a curing agent, a dispersant, an inhibitor, and a catalyst, and pressed into a sheet. After curing, a broadband thermally conductive absorbing gasket is obtained. The broadband thermally conductive absorbing gasket obtained in this manner has good thermal conductivity and flexibility, and can be easily adjusted in size according to actual installation requirements, thereby facilitating heat dissipation in electronic equipment and improving the stability and service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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.

[0016] Figure 1 This is a schematic diagram of the process of preparing the broadband heat-conducting and wave-absorbing gasket; Figure 2 This is another schematic flow chart of the method for preparing the broadband heat-conducting and wave-absorbing gasket; Figure 3 This is a graph showing the frequency and reflection loss obtained by testing the reflection loss of the broadband thermal conductive wave absorbing gasket; Figure 4 This is a graph showing frequency versus reflection loss obtained by testing the reflection loss of a sendust sheet that is not coated with polypyrrole. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below with reference to the accompanying drawings.

[0018] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

[0019] This embodiment relates to a method for preparing a broadband heat-conducting and wave-absorbing gasket, referring to Figure 1-Figure 2 , including the following steps: S100, performing preliminary treatment on the sendust powder to increase the surface roughness, ultrasonically dispersing the preliminarily treated sendust powder in a solution for 10 minutes, adding a coupling agent, stirring and reacting at 25° C. for 30 minutes, and then centrifuging and drying to obtain pretreated sendust powder; S200, adding pyrrole monomer and solvent into the reaction apparatus and stirring, adding initiator after stirring evenly, and continuing stirring, reacting at a reaction temperature of 50° C. to 60° C. for 3-5 hours to obtain a polypyrrole reaction system; S300, under nitrogen protection, adding the pretreated Sendust powder to the polypyrrole reaction system, and continuously stirring until the polypyrrole forms a coating layer on the surface of the Sendust powder; S400, after the reaction in step S300 is completed, separating the reaction mixture in step S300 to obtain polypyrrole-coated sendust powder, and washing and drying the polypyrrole-coated sendust powder; S500, mixing the dried polypyrrole-coated sendust powder with a polymer matrix material, a thermal conductive filler, a curing agent, a dispersant, an inhibitor, and a catalyst to obtain a mixture, pressing the mixture into a sheet, and curing the sheet to obtain a broadband thermal conductive wave absorbing gasket.

[0020] Specifically, in step S100, 1000g of spherical sendust with a particle size of 15μm is subjected to preliminary treatment, such as ball milling, for 30 minutes to increase its surface roughness and thereby enhance its bonding with the polypyrrole coating. The sendust powder is ultrasonically dispersed in 2000g of a 99.5% ethanol solution for 10 minutes to break up agglomerated sendust powder particles and uniformly disperse them in the ethanol solution. Next, 20g of hexadecyltrimethoxysiloxane is added, and the mixture is stirred at 25°C for 30 minutes to allow the hexadecyltrimethoxysiloxane, a coupling agent, to fully modify the sendust powder surface, further enhancing the interfacial bonding between the sendust powder and polypyrrole and improving the overall performance of the material. Finally, the pretreated sendust powder is centrifuged and dried for later use.

[0021] In the present embodiment, in step S200, the reaction apparatus is a round-bottom flask, the solvent is anhydrous ethanol, and the initiator is ammonium sulfate. 100-300g of pyrrole monomer is added to the round-bottom flask, and then 500g of anhydrous ethanol is added. After stirring evenly, ammonium sulfate is added and the mixture is stirred continuously. The reaction temperature is controlled at 60°C and the mixture is stirred and reacted for 5 hours to obtain a polypyrrole reaction system. In some embodiments, the reaction apparatus can also be a conical flask, and the initiator can also be hydrogen peroxide. The concentration of the pyrrole monomer is 0.1-0.5mol / L. In the present embodiment, the concentration of the pyrrole monomer is 0.1mol / L. In some embodiments, the concentration of the pyrrole monomer can also be 0.2mol / L.

[0022] In step S300, under nitrogen protection, the pretreated sendust powder is added to the polypyrrole reaction system and stirred for 3 hours until a polypyrrole coating is formed on the surface of the sendust powder. The nitrogen protection during the heating and stirring process helps prevent sendust oxidation at high temperatures.

[0023] In step S400 , after the reaction in step S300 is completed, the reaction mixture in step S300 is separated to obtain polypyrrole-coated sendust powder, and the polypyrrole-coated sendust powder is washed and dried.

[0024] In step S500, 600g of dried polypyrrole-coated sendust powder is mixed evenly with 250g of 90µm spherical alumina, 150g of 1µm spherical aluminum nitride, 50g of 500mPa•s vinyl silicone oil, 5g of 0.12% hydrogenated silicone oil, 2g of titanate coupling agent, 0.1g of inhibitor, and 2g of 2000ppm platinum catalyst in an open mill. The mixture is then degassed using a vacuum machine and pressed into 2mm sheets using a calendar. The sheets are then cured in a tunnel oven at 120-150°C for 10-20 minutes to produce a broadband thermally conductive absorbent gasket. Spherical alumina and spherical aluminum nitride serve as thermally conductive fillers. The spherical thermally conductive filler powder has a minimal effect on the system's thickening, and increasing the filler content can improve the thermal conductivity of the sendust. The inhibitor can be ethynylcyclohexanol. In some embodiments, the dried polypyrrole-coated sendust powder can be thoroughly mixed with a polymer matrix material, a thermal conductive filler, a curing agent, a dispersant, an inhibitor, and a catalyst in an internal mixer, and then prepared into a broadband thermal conductive wave absorbing gasket through a hot pressing process.

[0025] This method for preparing a broadband thermally conductive absorbing gasket coats sendust powder with polypyrrole, increasing its dielectric loss without sacrificing hysteresis loss, effectively widening the absorption bandwidth. The polypyrrole-coated sendust powder is then mixed with a polymer matrix material, a thermally conductive filler, a curing agent, a dispersant, an inhibitor, and a catalyst, and pressed into a sheet. After curing, the resulting broadband thermally conductive absorbing gasket exhibits excellent thermal conductivity and flexibility, allowing for easy size adjustment based on actual installation requirements. This facilitates heat dissipation in electronic equipment, improving device stability and service life.

[0026] This embodiment also relates to a broadband thermally conductive, wave-absorbing gasket, prepared by the broadband thermally conductive, wave-absorbing gasket preparation method described above. This broadband thermally conductive, wave-absorbing gasket comprises the following components by mass fraction: a functional filler: 50%-90%; the functional filler comprises: a sendust base and a polypyrrole layer coated on the sendust base; the sendust base has a particle size of 10-50 μm. The sendust base is a powder, and its particle size can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm. The sendust base particle size only needs to be in the range of 10-50 μm, and is not specifically limited here. As a conductive polymer, polypyrrole possesses a conjugated π-bond structure, allowing electrons to delocalize within the molecule, resulting in high conductivity. This allows for effective absorption of electromagnetic waves through mechanisms such as conductivity loss and polarization loss, exhibiting excellent dielectric loss characteristics. When attached to the surface of sendust, polypyrrole significantly enhances its absorption and bandwidth: it can absorb electromagnetic waves across a wide frequency range, meeting the absorption requirements of various frequencies. This broadband thermally conductive absorbing gasket, by coating the sendust-based surface with polypyrrole, effectively improves the absorption performance of the sendust and broadens the absorption frequency band, meeting the electromagnetic compatibility requirements of various electronic devices at different operating frequencies.

[0027] Furthermore, this broadband thermally conductive absorbing gasket also includes the following components in percentages by mass: polymer matrix material: 3%-10%; thermally conductive filler: 10%-40%; curing agent: 1%-5%; dispersant: 0.1%-1%; coupling agent: 0.1%-1%; inhibitor: 0.01%-0.02%; and catalyst: 0.1%-0.3%. The polymer matrix material is any one of epoxy resin, silicone rubber, and vinyl silicone oil. The thermally conductive filler is any one or more of alumina, aluminum nitride, boron nitride, or diamond. The thermally conductive filler is provided in the form of a spherical powder. The curing agent is 0.12% hydrogenated silicone oil. The coupling agent is any one of silane coupling agent, hexadecyltrimethoxysiloxane, titanate coupling agent, and aluminate coupling agent. The catalyst is a platinum catalyst. The inhibitor can be any one of ethynylcyclohexanol (ECH), methylbutynol (MBY), and dimethylhexynol (DMHD).

[0028] Reference Figure 3 Testing of the broadband thermally conductive absorbing gasket prepared through steps S100 to S500 (i.e., the present method for preparing a broadband thermally conductive absorbing gasket) revealed that its reflection loss remained below -8 dB at frequencies between 3 GHz and 8 GHz, with an absorption peak at 3.39 GHz, a maximum absorption value of -22.47 dB, and a thermal conductivity of 8 W / (m·K). These data demonstrate that directly coating the surface of sendust powder with polypyrrole broadens the absorption frequency band and exhibits excellent electromagnetic wave absorption.

[0029] Reference Figure 4 This figure shows the test of Sendust sheet of the same size as the broadband thermal absorbing gasket prepared by pressing Sendust powder that has not been coated with polypyrrole. The image data shows that the absorption peak is at 3.38GHz, the maximum absorption is -20.41dB, and the -8dB range is only between 2.34GHz and 3.34GHz, which is a narrow range.

[0030] Reference Figure 3-Figure 4 The broadband thermal conductive wave absorbing gasket prepared by the broadband thermal conductive wave absorbing gasket preparation method can effectively absorb electromagnetic waves in a wider frequency range.

[0031] The above is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a broadband heat-conducting and wave-absorbing gasket, characterized in that: The following steps are involved: S300, under nitrogen protection, adding the pretreated Sendust powder to the polypyrrole reaction system, and continuously stirring until the polypyrrole forms a coating layer on the surface of the pretreated Sendust powder; S400, after the reaction in step S300 is completed, separating the reaction mixture in step S300 to obtain polypyrrole-coated sendust powder, and washing and drying the polypyrrole-coated sendust powder; S500, mixing the dried polypyrrole-coated sendust powder with a polymer matrix material, a thermal conductive filler, a curing agent, a dispersant, an inhibitor, and a catalyst to obtain a mixture, pressing the mixture into a sheet, and curing the sheet to obtain a broadband thermal conductive wave absorbing gasket.

2. The method for preparing a broadband heat-conducting and wave-absorbing gasket according to claim 1, wherein: Before step S300, the following steps are also included: S200, adding pyrrole monomer and solvent into the reaction device and stirring, adding initiator after stirring evenly, and continuing stirring, reacting at a reaction temperature of 50° C.-60° C. for 3-5 hours to obtain the polypyrrole reaction system.

3. The method for preparing a broadband heat-conducting and wave-absorbing gasket according to claim 2, characterized in that: Before step S200, the following steps are also included: S100, performing preliminary treatment on the sendust powder to increase the surface roughness, ultrasonically dispersing the preliminarily treated sendust powder in a solution for 10 minutes, adding a coupling agent, stirring and reacting at 25° C. for 30 minutes, and then centrifuging and drying to obtain the pretreated sendust powder.

4. A broadband heat-conducting and wave-absorbing gasket, characterized in that: The broadband heat-conducting and wave-absorbing gasket is prepared by the preparation method of any one of claims 1 to 3.

5. The broadband heat-conducting and wave-absorbing gasket according to claim 4, characterized in that: The broadband heat-conducting and wave-absorbing gasket includes the following components by mass fraction: Functional filler: 50%-90%; The functional filler comprises: a sendust base and a polypyrrole layer coated on the surface of the sendust base; the particle size of the sendust base is set to 10-50 μm.

6. The broadband heat-conducting and wave-absorbing gasket according to claim 5, characterized in that: The broadband heat-conducting and wave-absorbing gasket further comprises the following components by mass fraction: Polymer matrix material: 3%-10%; Thermal conductive filler: 10%-40%; Curing agent: 1%-5%; Dispersant: 0.1%-1%; Coupling agent: 0.1%-1%; Inhibitor: 0.01%-0.02%; and Catalyst: 0.1%-0.3%.

7. The broadband heat-conducting and wave-absorbing gasket according to claim 5, characterized in that: The polymer matrix material is any one of epoxy resin, silicone rubber and vinyl silicone oil.

8. The broadband heat-conducting and wave-absorbing gasket according to claim 5, characterized in that: The thermal conductive filler is any one or more of aluminum oxide, aluminum nitride, boron nitride or diamond.

9. The broadband heat-conducting and wave-absorbing gasket according to claim 5, characterized in that: The thermally conductive filler is provided as spherical powder.

10. The broadband heat-conducting and wave-absorbing gasket according to claim 5, characterized in that: The curing agent is 0.12% hydrogen-containing silicone oil.

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