A rubber compound, low-density high-thermal-conductivity graphene foam and a preparation method thereof

Abstract

The application discloses a kind of mixing rubber, low-density high-thermal-conductivity graphene foam and preparation method thereof, it is related to heat dissipation material technical field.The raw material of the mixing rubber includes the following components: raw rubber of silicone rubber, MQ resin, white carbon black and modifier.The low-density high-thermal-conductivity graphene foam above described mixing rubber is base material, and includes high proportion modified graphene oxide powder, hydrogen-containing silicone oil, inhibitor, dispersing agent, color paste, foaming agent and catalyst.The mixing rubber is high in mechanical strength, suitable for high proportion filler filling and easy to uniform foaming, using the mixing rubber and other components synergistic design, the graphene foam prepared can simultaneously realize high thermal conductivity coefficient, low density, high tensile strength and excellent foaming uniformity, effectively solve the contradiction between high thermal conductivity filler filling and material mechanical property.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation materials technology, and in particular to a compound rubber, low-density high thermal conductivity graphene foam, and its preparation method. Background Technology

[0002] With the rapid development of electronic technology, consumer electronics products such as computers and mobile phones are increasingly becoming smaller and more powerful. The widespread adoption of new energy vehicles also places higher demands on the heat dissipation performance of their high-power onboard charging equipment. Foam materials, due to their excellent elasticity, light weight, ease of installation, and good shock absorption, are widely used inside electronic products as filling, sealing, and cushioning components. Among them, thermally conductive foam, based on traditional foam, incorporates thermal conductivity, enabling heat conduction at the interface while providing cushioning protection. It is one of the ideal materials for solving the heat dissipation problem of electronic components in confined spaces.

[0003] Currently, common thermally conductive foams mainly include PU foam, EVA foam, and thermally conductive silicone foam. However, the first two (PU and EVA) have significant problems with poor heat resistance, and are prone to deformation and aging under long-term high-temperature working environments, leading to failure of the thermal interface and decreased reliability. Thermally conductive silicone foam, with silicone rubber as its matrix, possesses excellent softness, resilience, and long-term thermal stability. To improve its thermal conductivity, it is usually necessary to fill the silicone matrix with a large amount of highly thermally conductive inorganic fillers such as alumina, boron nitride, or even graphene and carbon nanotubes. However, this technical approach has a significant inherent contradiction: while high filler content increases the thermal conductivity, it severely damages the mechanical and processing properties of the matrix material. During the production process, thermally conductive silicone foam is prone to breakage and deformation during die-cutting and stamping. Especially when producing smaller-sized foams, it is difficult to control the precise dimensions after die-cutting. Furthermore, during use, the thermally conductive silicone foam is also prone to deformation and breakage, thus reducing its quality.

[0004] In summary, existing thermally conductive foams struggle to achieve a good balance between thermal conductivity, mechanical strength, low density, and processing yield. Therefore, developing a matrix material that can simultaneously handle high filler load-bearing capacity, uniform foaming, and maintain strong toughness, as well as a foam material that simultaneously possesses low density, high thermal conductivity, excellent processability, and mechanical strength, has become a pressing technical challenge in this field. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a compound rubber, a low-density, high-thermal-conductivity graphene foam, and a method for preparing the same. The compound rubber is suitable for high-proportion filler filling, easy to foam uniformly, and has excellent mechanical strength. The graphene foam prepared using this compound rubber can simultaneously achieve high thermal conductivity, low density, high tensile strength, and excellent foaming uniformity, making it suitable for heat dissipation in high-end equipment such as on-board charging equipment for new energy vehicles.

[0006] This invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a compound for preparing thermally conductive foam, wherein the raw materials comprise the following components by weight: 45-55 parts of raw silicone rubber, 4-7 parts of MQ resin, 10-20 parts of silica, and 25-35 parts of modifier.

[0008] Preferably, the raw silicone rubber is selected from one or more of methyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, and fluorosilicone rubber.

[0009] Preferably, the viscosity of the MQ resin is 1000 to 100000 cps.

[0010] Preferably, the silica is selected from at least one of fumed silica and precipitated silica.

[0011] Preferably, the modifier is selected from one or more of hexamethyldisilazane, dimethyldichlorosilane, and polydimethylsiloxane.

[0012] Secondly, the present invention also provides a method for preparing the above-mentioned compound rubber, comprising the following steps:

[0013] (1) Mix the raw silicone rubber with MQ resin and knead at a speed of 30 r / min for 20 to 30 min;

[0014] (2) Add modifier and knead at 30 r / min for 10-20 min;

[0015] (3) Add silica, knead at 30 r / min for 10-20 min, then knead at 50 r / min for 20-30 min;

[0016] (4) Under a nitrogen protective atmosphere, dry at 180-200℃ for 2-4 hours to obtain the compound rubber.

[0017] Thirdly, the present invention provides a low-density, high-thermal-conductivity graphene foam, the raw materials of which, by weight, comprise the following components:

[0018] 300-500 parts of modified graphene oxide powder;

[0019] 90-110 parts of the above-mentioned compound rubber;

[0020] 1.5 to 2.5 parts of hydrogen-containing silicone oil;

[0021] Inhibitor 0.01~0.03 parts;

[0022] Dispersant 0.9~1.1 parts;

[0023] Color paste 0~1.0 parts;

[0024] 1.5-2.5 parts of foaming agent;

[0025] Catalyst 0.01~0.03 parts.

[0026] Preferably, the modified graphene oxide powder is prepared by the following method: a modifier, ethanol, and deionized water are mixed in a weight ratio of 4:4:2 and hydrolyzed for 2-4 hours to prepare a modification solution; the modification solution is mixed with graphene oxide powder in a weight ratio of 8:2, stirred evenly, ultrasonically treated, and dried to obtain the modified graphene oxide powder.

[0027] Preferably, the content of the pigment is 0.8 to 1.0 parts.

[0028] Preferably, the stirring speed is 1000 rpm / min and the stirring time is 20-30 min.

[0029] Preferably, the parameters for the ultrasonic treatment are: frequency 2000Hz, time 20-30min.

[0030] Preferably, the drying temperature is 120~150℃.

[0031] Preferably, the drying process further includes placing the graphene oxide at room temperature for 24-28 hours to allow the modifier to fully encapsulate the graphene oxide.

[0032] Preferably, the modifier is selected from one or more of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0033] Preferably, the silane coupling agent is selected from one or more of 3-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltrimethoxysilane (KH560), γ-(methacryloyloxy)propyltrimethoxysilane (KH570), dodecyltrimethoxysilane, vinyltriethoxysilane, and dodecylsilane.

[0034] Preferably, the hydrogen-containing silicone oil is a side-hydrogen-containing silicone oil, and the hydrogen content of the side-hydrogen-containing silicone oil is 0.1% to 1.5%.

[0035] Preferably, the inhibitor is selected from one or more of 2-vinylisopropanol, perchloroethylene, and acetylenecyclohexanol.

[0036] Preferably, the dispersant is selected from one or more of polyacrylate, polyvinyl ester, polyacrylamide, sodium dodecylbenzenesulfonate, dodecyl acetic acid, and polyester.

[0037] Preferably, the foaming agent is selected from one or more of benzoyl peroxide (BPO), di(2,4-dimethyl)sulfide, di(2,5-dimethyl)sulfide, and azobisisobutyronitrile.

[0038] Preferably, the catalyst is a platinum catalyst, and the platinum content of the platinum catalyst is 2000-5000 ppm.

[0039] Fourthly, the present invention also provides a method for preparing the above-mentioned low-density, high-thermal-conductivity graphene foam, comprising the following steps:

[0040] S1. Knead the above-mentioned compound rubber, hydrogen-containing silicone oil, inhibitor, dispersant and color paste evenly to obtain the base material;

[0041] S2. Mix the modified graphene oxide with the base material to obtain the thermally conductive base material;

[0042] S3. Add a foaming agent to the thermally conductive base material, mix, then add a catalyst, mix again to obtain the adhesive;

[0043] S4. After extruding and calendering the rubber material, foam it to obtain low-density, high-thermal-conductivity graphene foam.

[0044] Preferably, in step S1, the kneading speed is 30 r / min and the time is 20 min.

[0045] Preferably, in step S2, the mixing parameters are: two roller speeds of 30 r / min and time of 20 min.

[0046] Preferably, in step S3, the parameters for the two mixing operations are: two roller speeds of 30 r / min, time of 10 min, and temperature of 20~30℃.

[0047] Preferably, in step S4, the extrusion parameters are: extrusion rate of 100 g / s and vacuum degree of -0.08 MPa.

[0048] Preferably, in step S4, the linear speed of the calendering process is 0.8 m / min.

[0049] Preferably, in step S4, the foaming temperature is 120~150℃.

[0050] The present invention has the following technical effects:

[0051] The compound of this invention has excellent mechanical properties while ensuring the load-bearing capacity of a high proportion of thermally conductive fillers and easy uniform foaming. Adding it to graphene foam can make the graphene foam foam uniform and improve its mechanical properties, effectively avoiding damage and deformation problems in subsequent processing, and significantly improving the dimensional accuracy and production yield of the product.

[0052] This invention improves the tensile strength of graphene foam by compounding components such as rubber compound and hydrogen-containing silicone oil. Through the synergistic effect of the rubber compound and modified graphene oxide, the contradiction between high thermal conductivity and high mechanical properties is resolved. The graphene foam of this invention exhibits uniform foaming and structural stability. While maintaining a significant lightweight advantage with low density, it simultaneously achieves high thermal conductivity and excellent mechanical properties, successfully overcoming the technical bottleneck of traditional thermally conductive materials that struggle to balance thermal conductivity, density, and mechanical properties. Detailed Implementation

[0053] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] It should be understood that, when used in this specification and the appended claims, the terms “comprising” and “including” indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0055] It should be noted that the information on each raw material in the embodiments of the present invention is as follows:

[0056] Silicone rubber raw material: Dongjue, 110-2S;

[0057] MQ resin: Chenxi, CX-355;

[0058] Silica: Fumed silica (Cabot, TS-610).

[0059] Modifier: Hexamethyldisilazane (Spark);

[0060] Silane coupling agent: Dodecylsilane (Nanjing Nengde New Material Technology Co., Ltd., WDA-S317);

[0061] Hydrogen-containing silicone oil: Chenxi, CX-351H;

[0062] Inhibitor: Ethylenecyclohexanol (Guangdong Chenxi New Material Technology Co., Ltd., CX-5002H);

[0063] Dispersant: Polyacrylate (Guangdong Core New Materials Co., Ltd., disuper S26);

[0064] Foaming agent: Azobisisobutyronitrile (Dongguan Yongzheng Chemical Co., Ltd.);

[0065] Catalyst: Platinum catalyst with a platinum content of 2000ppm (Guangdong Chenxi New Material Technology Co., Ltd., CX-5001);

[0066] Graphene oxide: Da Ying Ju Neng, thickness 0.55~0.75nm.

[0067] Modified graphene oxide powder was prepared by the following method: a modifier, ethanol, and deionized water were mixed in a weight ratio of 4:4:2 and hydrolyzed for 3 hours to prepare a modification solution; the modification solution was mixed with graphene oxide powder in a weight ratio of 8:2 and stirred at 1000 rpm / min for 25 minutes, then ultrasonically treated with an ultrasonic frequency of 2000 Hz for 25 minutes, dried at 130℃, and left at room temperature for 36 hours to allow the modifier to fully coat the graphene oxide, thus obtaining modified graphene oxide powder.

[0068] It should be noted that the specific raw material models, specifications, and supplier information listed in the above embodiments are only for more clearly describing and verifying the technical solution of the present invention, and are not intended to limit the present invention. For those skilled in the art, within the scope of the formulation composition and performance requirements provided by the present invention, other commercially available or self-made equivalent raw materials that meet the requirements can be selected for substitution. All raw materials obtained by equivalent substitution or equivalent transformation should be considered to be included within the protection scope of the claims of the present invention.

[0069] To verify the technical effect of the compound of the present invention, compounds A1-A3 and compound B1 were prepared, and the component contents of their raw materials are shown in Table 1 below:

[0070] Table 1. Raw material component content of compound A1-A3 and compound B1

[0071]

[0072] The above components are used to prepare a compound rubber according to the following preparation method, which includes the following steps:

[0073] (1) Pour the raw silicone rubber and MQ resin into a kneader and mix them. Knead at a speed of 30 r / min for 25 min.

[0074] (2) Add modifier and knead at 30 r / min for 15 min;

[0075] (3) Add silica, knead at 30 r / min for 15 min, then knead at 50 r / min for 25 min;

[0076] (4) Under a nitrogen protective atmosphere, dry at 190°C for 3 hours to completely evaporate the moisture and modifier to obtain the compound rubber.

[0077] The prepared rubber compounds A1-A3 and B1 were subjected to mechanical property tests, specifically testing their hardness and tensile strength. The test results are shown in Table 2 below.

[0078] Table 2 Test results of mechanical properties of rubber compound

[0079]

[0080] As shown in Table 2, the compound rubber using the technical solution of this application has good mechanical properties.

[0081] To further illustrate the technical solution of the present invention, the following examples and comparative examples of graphene foam are provided. The raw material component content of the graphene foam in each example and comparative example is shown in Table 3 below:

[0082] Table 3. Raw material component content of the examples and comparative examples

[0083]

[0084] The above components are used to prepare graphene foam according to the following method, which includes the following steps:

[0085] S1. Add the above-mentioned compound rubber / raw rubber, hydrogen-containing silicone oil, inhibitor, dispersant and color paste into a kneader and knead for 20 minutes at a speed of 30 r / min to obtain the base material;

[0086] S2. Add the modified graphene oxide / modified alumina / graphene oxide (untreated) to the kneader and mix it with the base material. Knead for 10 minutes at a two-roll speed of 30 r / min to obtain the thermally conductive base material.

[0087] S3. Add foaming agent to heat-conducting base material, knead for 10 minutes at a speed of 30 r / min with two rollers while cooling water is circulated through the kneader at 25°C, then add catalyst and knead for 10 minutes at a speed of 30 r / min with two rollers to obtain rubber material.

[0088] S4. Place the rubber compound into an extruder, set the extrusion rate to 100g / s and the vacuum degree to -0.08Mpa, and extrude the rubber compound; calender the extruded rubber compound at a linear speed of 0.8m / min, and then foam it in a tunnel furnace at a temperature of 135℃ to obtain graphene foam with a thickness of 2.5±0.5mm.

[0089] The graphene foams prepared in Examples 1-9 and Comparative Examples 1-4 were subjected to thermal conductivity tests, density tests, and tensile strength tests, and their foaming behavior was observed. The test results are shown in Table 4 below:

[0090] Table 4 Performance test results of graphene foams prepared in Examples 1-9 and Comparative Examples 1-4

[0091]

[0092] As shown in Table 4, all embodiments of the present invention consistently exhibit excellent overall performance, including high thermal conductivity (>10 W / (m·K)), low density (<1.24 g / cm³), high strength (>1.13 MPa), and uniform foaming. In contrast, in the comparative examples, the absence of one or more key elements of the present invention leads to a significant deterioration in one or more of its key properties.

[0093] In summary, the technical solution of the present invention has a significant synergistic effect, jointly resolving the long-standing contradiction between the high thermal conductivity filler and the requirements for the mechanical properties, processing performance, and low density of the matrix material.

[0094] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-density, high-thermal-conductivity graphene foam, characterized in that, By weight, its raw materials include the following components: 300-500 parts of modified graphene oxide powder; 90-110 parts of compounded rubber; 1.5 to 2.5 parts of hydrogen-containing silicone oil; Inhibitor 0.01~0.03 parts; Dispersant 0.9~1.1 parts; Color paste 0~1.0 parts; 1.5 to 2.5 parts of foaming agent; Catalyst: 0.01~0.03 parts; The modified graphene oxide powder was prepared by the following method: the modifier, ethanol and deionized water were mixed in a weight ratio of 4:4:2 and hydrolyzed for 2-4 hours to prepare a modification solution; the modification solution and graphene oxide powder were mixed in a weight ratio of 8:2, stirred evenly and then subjected to ultrasonic treatment and dried to obtain the modified graphene oxide powder. The modifier is selected from one or more of silane coupling agents, titanate coupling agents, and aluminate coupling agents; The compound rubber comprises the following components by weight: 45-55 parts of raw silicone rubber, 4-7 parts of MQ resin, 10-20 parts of silica, and 25-35 parts of modifier; the modifier is selected from one or more of hexamethyldisilazane, dimethyldichlorosilane, and polydimethylsiloxane.

2. The low-density, high-thermal-conductivity graphene foam as described in claim 1, characterized in that, The silica is selected from at least one of fumed silica and precipitated silica.

3. A low-density, high-thermal-conductivity graphene foam as described in claim 1, characterized in that, The compound rubber is prepared by the following steps: (1) Mix the raw silicone rubber with MQ resin and knead at a speed of 30 r / min for 20 to 30 min; (2) Add modifier and knead at 30 r / min for 10-20 min; (3) Add silica, knead at 30 r / min for 10-20 min, then knead at 50 r / min for 20-30 min; (4) Under a nitrogen protective atmosphere, dry at 180-200℃ for 2-4 hours to obtain the compound rubber.

4. The low-density, high-thermal-conductivity graphene foam as described in claim 1, characterized in that, The foaming agent is selected from one or more of benzoyl peroxide and azobisisobutyronitrile.

5. The low-density, high-thermal-conductivity graphene foam as described in claim 1, characterized in that, The catalyst is a platinum catalyst, and the platinum content of the platinum catalyst is 2000-5000 ppm.

6. A method for preparing low-density, high-thermal-conductivity graphene foam as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Knead the hydrogen-containing silicone oil, inhibitor, dispersant, color paste and compound rubber evenly to obtain the base material; S2. Mix the modified graphene oxide with the base material to obtain the thermally conductive base material; S3. Add a foaming agent to the thermally conductive base material, mix, then add a catalyst, mix again to obtain the adhesive; S4. After extruding and calendering the rubber material, foam it to obtain low-density, high-thermal-conductivity graphene foam.

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