A shielding and heat dissipating material containing graphene and a method for producing the same

Abstract

The present application relates to the technical field of functional composite materials, and particularly relates to a shielding and heat dissipating material containing graphene and a production method thereof, which comprises a polymer matrix, graphene dispersed in the polymer matrix and optional metal micro / nano particles, the graphene and the metal micro / nano particles are mutually overlapped in the matrix to form a three-dimensional continuous network structure. The present application builds an interconnected three-dimensional network in the material interior through the synergistic effect of functionalized graphene and metal particles, and the network can be used as a channel for fast migration of electrons to realize electromagnetic shielding and can be used as a high-speed path for phonon transmission to realize efficient heat diffusion.

Description

Technical Field

[0001] This invention relates to the field of functional composite materials technology, and in particular to a graphene-containing shielding and heat dissipation material and its production method. Background Technology

[0002] As electronic devices develop towards higher frequencies, higher speeds, and higher integration, their internal electromagnetic interference (EMI) becomes increasingly serious. At the same time, the heat generation power of components such as chips increases dramatically. EMI can affect the normal operation of equipment and data security, while heat accumulation can reduce equipment reliability and shorten its service life. Therefore, developing materials that combine electromagnetic shielding and efficient heat dissipation has become crucial.

[0003] Currently, commonly used shielding and heat dissipation solutions mostly use metal materials (such as aluminum and copper) or lay out a shielding layer and thermally conductive interface material (TIM) separately. Metal materials have high density and are easily corroded, and their shielding effectiveness (SE) is limited at high frequencies due to the skin effect. Split-type solutions increase assembly complexity and interface thermal resistance.

[0004] Graphene is considered an ideal material for shielding and heat dissipation due to its ultra-high electrical conductivity, thermal conductivity, light weight, and huge specific surface area. However, single graphene films or foams have problems such as poor mechanical strength, difficulty in integration with existing processes, and high cost in practical applications. Summary of the Invention

[0005] Therefore, the present invention provides a graphene-containing shielding and heat dissipation material and its production method to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a shielding and heat dissipation material containing graphene and its production method, comprising a polymer matrix, graphene dispersed in the polymer matrix, and optional metal micro / nanoparticles, wherein the graphene and the metal micro / nanoparticles overlap each other in the matrix to form a three-dimensional continuous network structure.

[0007] Preferably, by weight, it comprises: 100 parts of polymer matrix, 5-50 parts of graphene, and 0-30 parts of metal micro / nanoparticles.

[0008] Preferably, the graphene is graphene that has undergone oxidation, amination, silanization, or polymer grafting treatment, and has fewer than 10 layers.

[0009] Preferably, the metal micro / nanoparticles are spherical, sheet-like, or fibrous particles of silver, copper, nickel, aluminum, or their alloys.

[0010] A method for producing a graphene-containing shielding and heat dissipation material includes the following steps: S1: Functionalize graphene to obtain a graphene dispersion; S2: Mix the graphene dispersion, optional metal micro / nanoparticles, dispersant and coupling agent to prepare a composite slurry; S3: The composite slurry is blended with the polymer matrix under high shear and the solvent is removed to obtain the composite material; S4: The composite material is molded and cured to obtain the shielding and heat dissipation material.

[0011] Preferably, in step S1, the functionalization process includes oxidation treatment and subsequent chemical reduction and surface modification.

[0012] Preferably, in step S3, the high-shear blending is carried out in a vacuum environment at a rotation speed of 1000~5000 rpm.

[0013] Preferably, in step S4, for thermosetting substrates, hot pressing is used for curing; for thermoplastic substrates or prepolymers, casting or coating followed by heat treatment is used for molding.

[0014] The beneficial effects of this invention are: This invention constructs an interconnected three-dimensional network within the material through the synergistic effect of functionalized graphene and metal particles. This network can serve as a channel for rapid electron migration to achieve electromagnetic shielding, and as a high-speed path for phonon transmission to achieve efficient thermal diffusion.

[0015] This invention allows for precise control of the electrical conductivity, thermal conductivity, and mechanical properties of materials by adjusting the type, content, and functionalization degree of graphene, as well as the type and morphology of metal particles, to adapt to different application scenarios.

[0016] This invention employs a two-step method: first, a stable functionalized graphene / metal composite slurry is prepared, and then it is blended with a matrix. This effectively solves the problem of easy graphene agglomeration, ensures uniform dispersion of nanofillers in macroscopic materials, and provides a stable process suitable for continuous production. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a schematic diagram of the material composition of Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the material composition of Embodiment 3 of the present invention; Figure 4 This is a schematic diagram of the material composition of Embodiment 4 of the present invention. Detailed Implementation

[0018] To further explain the technical solution of the present invention, a detailed description is provided below through specific embodiments.

[0019] Example 1:

[0020] This invention provides a graphene-containing shielding and heat dissipation material and its production method, comprising a polymer matrix, graphene dispersed in the polymer matrix, and optional metal micro / nanoparticles, wherein the graphene and the metal micro / nanoparticles overlap each other in the matrix to form a three-dimensional continuous network structure.

[0021] Specifically, the shielding and heat dissipation material, by weight, includes: 100 parts of polymer matrix, 5-50 parts of graphene, and 0-30 parts of metal micro / nanoparticles. The auxiliary dispersant is 0.5 to 5 parts. The coupling agent is 1 to 8 parts. Other functional additives (antioxidants, plasticizers, etc.); 0-10 parts; The polymer matrix is ​​one or more of silicone rubber, epoxy resin, polyurethane, polyimide, polycarbonate or polyolefin.

[0022] The graphene in question is graphene that has undergone oxidation, amination, silanization, or polymer grafting treatment, and has fewer than 10 layers.

[0023] The metal micro / nanoparticles are spherical, sheet-like, or fibrous particles of silver, copper, nickel, aluminum, or their alloys, with an average particle size of 10 nm to 50 μm; the graphene and metal particles overlap to form a through-hole three-dimensional conductive / thermal conductive network within the polymer matrix.

[0024] Example 2:

[0025] The shielding and heat dissipation material, by weight, comprises: 100 parts polymer matrix, 15 parts graphene, and 15 parts metal micro / nanoparticles. The auxiliary dispersant consists of 3 parts. The coupling agent consists of 2 parts. Among them, other functional additives (antioxidants, plasticizers, etc.); 3 parts; The polymer matrix is ​​silicone rubber; The graphene in question is graphene that has undergone oxidation, amination, silanization, or polymer grafting treatment, and has fewer than 10 layers.

[0026] The metal micro / nanoparticles are spherical, sheet-like, or fibrous particles of silver, copper, nickel, aluminum, or their alloys, with an average particle size of 10 nm to 50 μm; the graphene and metal particles overlap to form a through-hole three-dimensional conductive / thermal conductive network within the polymer matrix.

[0027] Example 3:

[0028] The shielding and heat dissipation material, by weight, comprises: 100 parts polymer matrix, 40 parts graphene, and 10 parts metal micro / nanoparticles. Of which, auxiliary dispersant: 2 parts; The coupling agent consists of 3 parts. Among them, other functional additives (antioxidants, plasticizers, etc.); 4 parts; The polymer matrix is ​​polycarbonate or polyolefin; The graphene in question is graphene that has undergone oxidation, amination, silanization, or polymer grafting treatment, and has fewer than 10 layers.

[0029] The metal micro / nanoparticles are spherical, sheet-like, or fibrous particles of silver, copper, nickel, aluminum, or their alloys, with an average particle size of 10 nm to 50 μm; the graphene and metal particles overlap to form a through-hole three-dimensional conductive / thermal conductive network within the polymer matrix.

[0030] Example 4;

[0031] The shielding and heat dissipation material, by weight, comprises: 100 parts polymer matrix, 15 parts graphene, and 15 parts metal micro / nanoparticles. The auxiliary dispersant consists of 3 parts. The coupling agent consists of 2 parts. Among them, other functional additives (antioxidants, plasticizers, etc.); 4 parts; The polymer matrix is ​​polyurethane; The graphene in question is graphene that has undergone oxidation, amination, silanization, or polymer grafting treatment, and has fewer than 10 layers.

[0032] The metal micro / nanoparticles are spherical, sheet-like, or fibrous particles of silver, copper, nickel, aluminum, or their alloys, with an average particle size of 10 nm to 50 μm; the graphene and metal particles overlap to form a through-hole three-dimensional conductive / thermal conductive network within the polymer matrix.

[0033] Example 5:

[0034] like Figure 1 As shown, a method for producing a graphene-containing shielding and heat dissipation material includes the following steps: S1: Functionalize graphene to obtain a graphene dispersion; S2: Mix the graphene dispersion, optional metal micro / nanoparticles, dispersant and coupling agent to prepare a composite slurry; S3: The composite slurry is blended with the polymer matrix under high shear and the solvent is removed to obtain the composite material; S4: The composite material is molded and cured to obtain the shielding and heat dissipation material.

[0035] Specifically, the functionalization process includes oxidation treatment followed by chemical reduction and surface modification.

[0036] In step S3, the high-shear blending is carried out in a vacuum environment at a rotation speed of 1000~5000 rpm.

[0037] In step S4, for thermosetting substrates, hot pressing is used for curing; for thermoplastic substrates or prepolymers, casting or coating followed by heat treatment is used for molding.

[0038] More specifically: Graphene functionalization pretreatment: 10g of natural flake graphite was prepared into a graphene oxide (GO) aqueous dispersion (2mg / mL) using a modified Hummers method. 1g of silane coupling agent KH-550 was added to the dispersion, and the reaction was carried out at 80℃ for 6 hours. Then, hydrazine hydrate was added for reduction to obtain an amino-functionalized reduced graphene oxide (rGO-NH2) suspension. The Hummers process utilizes a mixture of a strong protic acid (concentrated sulfuric acid) and a strong oxidant (potassium permanganate) to intercalate and deeply oxidize natural graphite. In concentrated sulfuric acid, sulfuric acid molecules intercalate between graphite layers to form graphite intercalation compounds. Subsequently, potassium permanganate in an acidic environment produces highly reactive manganese anhydride, which attacks the carbon atoms on the benzene rings in the graphite sheets, introducing a large number of oxygen-containing functional groups, such as hydroxyl and epoxy groups (located on the basal plane), as well as carboxyl and carbonyl groups (located on the edge). This process disrupts the conjugated structure of graphite and increases the interlayer spacing. Finally, through the mechanical action of ultrasound or stirring, the graphite sheets are exfoliated into single sheets or a few layers of graphene oxide. Step A: Low-temperature pre-reaction; Under intense cooling and stirring conditions in an ice-water bath (0-5℃), 1 part by weight of natural graphite powder or flake graphite is slowly added to a reaction vessel containing 23 parts by weight of concentrated sulfuric acid. Maintaining a low temperature is to prevent the initial reaction from being too vigorous; While continuously stirring, slowly add 3 parts by weight of potassium permanganate. The addition rate must be strictly controlled during this process, and the temperature must be maintained below 20°C. The addition of potassium permanganate is an exothermic reaction; low temperature is crucial for safety. Step B: Intermediate-temperature oxidation Remove the ice-water bath and heat the reaction system to 35±5℃. Continue stirring at this temperature for 2-6 hours. At this point, the mixture will gradually turn into a paste-like dark green or brownish-black color, indicating the oxidation reaction is progressing.

[0039] Step C: High-temperature curing and termination; Slowly add 46 parts by weight of deionized water to the reaction system. Note: Adding water is a violently exothermic process and must be done slowly and carefully, preferably in an ice-water bath. The addition of water will cause the temperature to rise rapidly to 90-100℃, and the solution color will turn bright yellow or brownish-yellow.

[0040] Maintain this high-temperature reaction for 15-30 minutes to further oxidize and decompose some of the excess manganate.

[0041] Step D: Reaction termination and removal of reducing agent After cooling the reaction system back to room temperature, a large amount of deionized water was added for dilution.

[0042] Then, hydrogen peroxide solution is slowly added dropwise until the mixture turns a brilliant golden yellow and no more bubbles are produced. The hydrogen peroxide is used to reduce excess potassium permanganate and the generated manganese dioxide in the reaction, converting them into soluble manganese sulfate.

[0043] After standing, a distinct yellow supernatant and possible flocculent precipitate can be observed.

[0044] Step E: Purification Graphene oxide precipitate is collected by centrifugation or filtration.

[0045] The precipitate is repeatedly washed with dilute hydrochloric acid (such as 5% HCl solution) and deionized water until the pH of the supernatant is close to neutral and no white precipitate is detected by barium chloride solution (indicating that sulfate ions have been washed away). This purification process is crucial for removing metal ion impurities.

[0046] Step F: Dispersion The purified graphene oxide filter cake was redispersed in deionized water or a specific organic solvent and subjected to ultrasonic treatment (100-400W power, 30-120 minutes) to fully exfoliate it, finally obtaining a brownish-yellow, uniform and stable graphene oxide dispersion.

[0047] Preparation of composite slurry: Take all of the above rGO-NH2 suspension (equivalent to 5 parts of graphene), add flake silver powder (10 parts, average diameter 2μm), 3 parts of silane coupling agent KH-560 and 1 part of dispersant (polyvinylpyrrolidone), mix in ethanol by ultrasonication and high-speed shearing (3000rpm, 60 minutes) to obtain a uniform silver slurry. Matrix blending: 100 parts of liquid silicone rubber (107 rubber) were mixed with the above slurry in a planetary mixer under vacuum (2000 rpm, 90 minutes), and heated to 80°C to remove ethanol; Molding and curing: The uniformly mixed material is injected into a 100mm×100mm×2mm mold, and hot-pressed and vulcanized at 120℃ for 1 hour. After demolding, the silicone rubber-based shielding heat sink is obtained.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A heat-dissipating shielding material containing graphene, characterized in that: It includes a polymer matrix, graphene dispersed in the polymer matrix, and optional metal micro / nanoparticles, wherein the graphene and the metal micro / nanoparticles overlap each other in the matrix to form a three-dimensional continuous network structure.

2. The graphene-containing shielding and heat dissipation material according to claim 1, characterized in that: By weight, it includes: 100 parts polymer matrix, 5-50 parts graphene, and 0-30 parts metal micro / nanoparticles.

3. A graphene-containing shielding and heat dissipation material according to claim 1 or 2, characterized in that: The graphene is graphene that has undergone oxidation, amination, silanization, or polymer grafting treatment, and has fewer than 10 layers.

4. The graphene-containing shielding and heat dissipation material according to claim 2, characterized in that: The metal micro / nanoparticles are spherical, plate-like, or fibrous particles of silver, copper, nickel, aluminum, or their alloys.

5. A method for producing a graphene-containing shielding and heat dissipation material, used to produce the shielding and heat dissipation material according to claims 1 to 4, characterized in that: Includes the following steps: S1: Functionalize graphene to obtain a graphene dispersion; S2: Mix the graphene dispersion, optional metal micro / nanoparticles, dispersant and coupling agent to prepare a composite slurry; S3: The composite slurry is blended with the polymer matrix under high shear and the solvent is removed to obtain the composite material; S4: The composite material is molded and cured to obtain the shielding and heat dissipation material.

6. The method for producing a graphene-containing shielding and heat dissipation material according to claim 5, characterized in that: In step S1, the functionalization process includes oxidation treatment and subsequent chemical reduction and surface modification.

7. A method for producing a graphene-containing shielding and heat dissipation material according to claim 5, characterized in that: In step S3, the high-shear blending is carried out in a vacuum environment at a rotation speed of 1000~5000 rpm.

8. A method for producing a graphene-containing shielding and heat dissipation material according to claim 5, characterized in that: In step S4, for thermosetting substrates, hot pressing is used for curing; for thermoplastic substrates or prepolymers, casting or coating followed by heat treatment is used for molding.

Images