Graphene heating coating and preparation method thereof

Abstract

According to the graphene exothermic coating and the preparation method thereof, nitrogen-doped graphene and graphene oxide are used as heat conduction materials, the heat resistance of the exothermic coating can be remarkably improved through the synergistic effect, and meanwhile the heat resistance, adhesive force and durability of a coating can be remarkably improved through an in-situ polymerization process.

Description

Technical Field

[0001] The present invention belongs to the field of coatings, and in particular relates to a graphene heating coating and a preparation method thereof. Background Art

[0002] With the rapid development of materials science and nanotechnology, graphene has become an ideal choice for functional heating materials due to its unique two-dimensional structure, excellent electrical and thermal conductivity, and good mechanical flexibility. Graphene heating coatings convert electrical energy into heat through the Joule effect, offering advantages such as uniform heating, rapid response, and controllable temperature. These coatings have attracted widespread attention in the smart home and wearable device sectors. In particular, they can provide a gentle and stable thermal therapeutic effect, significantly relieving muscle fatigue and improving local microcirculation.

[0003] Traditional heating materials, such as metal wire and carbon fiber, suffer from poor flexibility and uneven heating. Graphene heating coatings can perfectly overcome these shortcomings. Research has shown that graphene, due to its ultra-high electrical and thermal conductivity (~5300 W / (m·K)) and mechanical strength, is an ideal heating material. Low-temperature hyperthermia at 40-45°C can effectively dilate capillaries, increase blood flow, and promote metabolism. Graphene also exhibits far-infrared radiation properties. Its 4-14μm wavelength far-infrared radiation matches the human body's absorption band, generating resonant absorption and further enhancing the therapeutic effect. However, conventional graphene easily aggregates and exhibits weak interfacial bonding with the polymer matrix, hindering the formation of a conductive network. Research on graphene heating coatings has primarily relied on physical blending methods, which results in poor filler dispersion and low heating efficiency. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the purpose of the present invention is to provide a graphene heating coating and a preparation method thereof, which significantly improves the thermal conductivity, adhesion and durability of the coating through nitrogen doping modification and in-situ polymerization process.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A graphene heating paint, characterized by comprising 1-30% nitrogen-doped graphene, 1-30% modified graphene nanoparticles, 5-15% methyl methacrylate, 5-15% styrene, 18-30% isooctyl acrylate, 0.5-5% methacrylic acid, 0.5-5% AMPS, 0.5-5% hydroxyethyl methacrylate, 0.5-3% crosslinking agent, 3% silane coupling agent, 0.5-1.5% emulsifier, 0.01-0.06% initiator, and the balance deionized water.

[0006] Preferably, the preparation method of the nitrogen-doped graphene is to disperse graphene oxide in an alkaline solution, ultrasonically treat for 1-3 hours; under nitrogen protection, hydrothermally react at 180-250° C. for 10-15 hours, cool, wash, and freeze-dry to obtain nitrogen-doped graphene.

[0007] Preferably, the mass ratio of the graphene oxide to the alkaline solution is 1:5-85.

[0008] Preferably, the alkaline solution is one or more of urea, hydrazine hydrate, ammonia water, and melamine.

[0009] Preferably, the preparation method of the nitrogen-doped graphene is to disperse graphene oxide in an alkaline solution, ultrasonically treat for 1.5 hours; hydrothermally react at 180° C. for 12 hours under nitrogen protection, cool, wash, and freeze-dry to obtain nitrogen-doped graphene.

[0010] Preferably, the preparation method of the modified graphene nanoparticles is to disperse epoxy acrylate monomer and graphene oxide in water, stir to form a suspension, continue stirring and heat to 30-80° C., react for 1-2 hours, filter, wash and dry to obtain modified graphene nanoparticles.

[0011] Preferably, the epoxy acrylate monomer is one or more of glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether.

[0012] Preferably, the mass ratio of the graphene oxide to the epoxy acrylate monomer is 1:10-30.

[0013] Preferably, the mass ratio of the nitrogen-doped graphene to the modified graphene nanoparticles is 1:2-8.

[0014] Preferably, the mass ratio of the nitrogen-doped graphene to the modified graphene nanoparticles is 1:3-5.

[0015] Preferably, the cross-linking agent includes one or more of diacetone acrylamide, pentaerythritol triacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate, and N,N'-methylenebisacrylamide.

[0016] Preferably, the cross-linking agent is diacetone acrylamide.

[0017] Preferably, the silane coupling agent includes one or more of an aminosilane coupling agent, an epoxysilane coupling agent, a methacryloxysilane coupling agent, a mercaptosilane coupling agent, a vinylsilane coupling agent, and an alkylsilane coupling agent.

[0018] Preferably, the silane coupling agent is an aminosilane coupling agent.

[0019] Preferably, the silane coupling agent is one or more of a vinyl silane coupling agent and an alkyl silane coupling agent.

[0020] Preferably, the emulsifier includes one or more of sodium stearate, SDS, SLS, OP, Tween, and Span.

[0021] Preferably, the initiator is one or more of APS, KPS, BPO, AIBN, AIVN, and redox initiators.

[0022] A method for preparing a graphene heating coating, characterized by comprising the following steps: Step 1: Modified graphene nanoparticles, methyl methacrylate, styrene, isooctyl acrylate, methacrylic acid, hydroxyethyl methacrylate, AMPS, N,N'-methylenebisacrylamide, initiator, emulsifier and deionized water are mixed in sequence and stirred until uniformly dispersed to prepare a pre-emulsion; Step 2: Mix nitrogen-doped graphene and silane coupling agent, stir for 0.5-1h, continue to add 1 / 3 of the pre-emulsion, mix, and ultrasonicate for 10-30min to obtain a seed pre-emulsion; Step 3: Add seed pre-emulsion to the reactor, start stirring, heat to 45-85°C, react for 10-45 minutes to obtain seed emulsion, then add the remaining pre-emulsion to the reactor, add it within 0.5-3 hours, add redox initiator, continue to keep warm for 0.5-2 hours, cool down, discharge the material, and obtain the heating coating.

[0023] The beneficial effects of the present invention are: 1) The present invention uses nitrogen-doped graphene and graphene oxide as thermal conductive materials at the same time, which can significantly improve the thermal conductivity of the heating coating through synergistic effect.

[0024] 2) The carboxyl, hydroxyl and other active oxygen-containing groups on the graphene oxide of the present invention undergo a ring-opening reaction with the epoxy groups of the epoxy acrylate monomer, which can introduce polymerizable double bonds on the surface of the graphene oxide, enabling it to copolymerize with the acrylate monomer, thereby improving the dispersion uniformity of the graphene oxide in the resin matrix, thereby improving the adhesion, durability and heat resistance of the heat-generating coating.

[0025] 3) The present invention first uses an aminosilane coupling agent to pretreat the nitrogen-doped graphene, and at the same time uses diacetone acrylamide as a cross-linking agent to generate a reversible imine bond through a Schif base reaction between the ketone group and the amino group, so that the graphene heating coating has a self-healing function, maintains the integrity of the microscopic three-dimensional network structure, and improves the durability and heat resistance of the heating coating. DETAILED DESCRIPTION

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The present invention will be further explained below in conjunction with specific embodiments.

[0027] Preparation Example 1 The preparation method of nitrogen-doped graphene is as follows: Graphene oxide was dispersed in a urea solution, ultrasonically treated for 1 hour, hydrothermally reacted at 180°C for 12 hours under nitrogen protection, cooled, washed, and freeze-dried to obtain nitrogen-doped graphene. The mass ratio of graphene oxide to urea was 1:10.

[0028] Preparation Example 2 The preparation method of modified graphene nanoparticles is as follows: Glycidyl acrylate and graphene oxide were dispersed in water, stirred to form a suspension, and then heated to 60°C with continued stirring for 1 hour. The mixture was then filtered, washed, and dried to obtain modified graphene nanoparticles. The mass ratio of graphene oxide to glycidyl acrylate was 1:20.

[0029] Example 1 The raw materials of the graphene heating coating include 3% nitrogen-doped graphene prepared in Preparation Example 1, 12% modified graphene nanoparticles prepared in Preparation Example 2, 6% methyl methacrylate, 6% styrene, 25% isooctyl acrylate, 3% methacrylic acid, 2% AMPS, 3% hydroxyethyl methacrylate, 1% N,N'-methylenebisacrylamide, 3% silane coupling agent KH550, 1.2% emulsifier SDS, 0.05% initiator AIBN, and the balance deionized water.

[0030] The preparation method of the graphene heating coating includes: Step 1: The modified graphene nanoparticles prepared in Preparation Example 2, methyl methacrylate, styrene, isooctyl acrylate, methacrylic acid, hydroxyethyl methacrylate, AMPS, N,N'-methylenebisacrylamide, an initiator, an emulsifier, and deionized water are sequentially mixed and stirred until uniformly dispersed to prepare a pre-emulsion; Step 2: The nitrogen-doped graphene prepared in Preparation Example 1 and the aminosilane coupling agent KH550 were mixed, stirred for 0.5 h, and 1 / 3 of the pre-emulsion was added, mixed, and ultrasonicated for 20 min to obtain a seed pre-emulsion; Step 3: Add seed pre-emulsion to the reactor, start stirring, heat to 65°C, react for 30 minutes to obtain seed emulsion, then add the remaining pre-emulsion to the reactor, add it within 2 hours, add redox initiator, continue to keep warm for 1 hour, cool down, discharge the material, and obtain the heating coating.

[0031] Example 2 A graphene heating paint is prepared according to the method of Example 1, with the only difference being that N,N-methylenebisacrylamide is replaced by diacetone acrylamide.

[0032] Example 3 A graphene heating paint was prepared according to the method of Example 1, with the only difference being that the aminosilane coupling agent KH550 was replaced by a methacryloyloxy silane coupling agent KH570.

[0033] Comparative Example 1 A graphene heating paint is prepared according to the method of Example 1, except that the modified graphene nanoparticles prepared in Preparation Example 2 in step 1 are replaced by nitrogen-doped graphene and aminosilane coupling agent KH550 prepared in Preparation Example 1, wherein the mass ratio of nitrogen-doped graphene to aminosilane coupling agent KH550 is 1:1.

[0034] Comparative Example 2 A graphene heating paint is prepared according to the method of Example 1, with the only difference being that the nitrogen-doped graphene and aminosilane coupling agent KH550 prepared in Preparation Example 1 in step 2 are replaced by modified graphene nanoparticles prepared in Preparation Example 2.

[0035] Performance Testing The graphene heating coatings obtained in Examples 1-3 and Comparative Examples 1-2 were respectively applied to the surface of an ABS board, and dried at elevated temperature to form a coating with a thickness of 20 μm. The performance of the coatings was then characterized. Adhesion: Adhesion test is conducted according to GB / T1720-2020. The adhesion of the coating is divided into different levels from 0 to 5, with 0 indicating the best adhesion and 5 indicating the worst adhesion.

[0036] Moisture and heat resistance: According to GB / T9274-07, the moisture and heat resistance of the product is tested at a temperature of 45°C and a humidity of 95%.

[0037] Thermal conductivity: According to GB / T32064-2015, the thermal conductivity of the coating is tested.

[0038] Table 1 Performance of graphene heating coating From the comparison of Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that the graphene heating coating prepared in Example 1 of the present invention has better effects in adhesion, adhesion after treatment at 250°C for 1 hour, moisture and heat resistance, and thermal conductivity. This may be because in Example 1, nitrogen-doped graphene and graphene oxide are used as thermal conductive materials at the same time, and the thermal conductivity of the heating coating can be significantly improved through synergistic effect; and, the active oxygen-containing groups such as carboxyl and hydroxyl groups on the graphene oxide of the present invention undergo a ring-opening reaction with the epoxy groups of the epoxy acrylate monomer, and polymerizable double bonds can be introduced on the surface of the graphene oxide, so that it can copolymerize with the acrylate monomer, thereby improving the dispersion uniformity and bonding strength of the graphene oxide in the resin matrix, thereby improving the adhesion, durability and heat resistance of the heating coating.

[0039] From the comparison of Example 1, Example 2 and Example 3, it can be seen that the graphene heating coating prepared in Example 2 of the present invention has better adhesion, moisture and heat resistance and thermal conductivity after being treated at 250°C for 1 hour. This may be because in Example 2, the nitrogen-doped graphene is first pretreated with aminosilane coupling agent KH550, and then fully mixed with acrylic monomers and modified graphene oxide particles with polymerizable double bonds on the surface, and then subjected to in-situ polymerization reaction, which can significantly improve the dispersion uniformity and bonding strength of nitrogen-doped graphene in the resin matrix. At the same time, diacetone acrylamide is used as a cross-linking agent, and its ketone group can react with the amino group of aminosilane coupling agent KH550 to undergo Schif base reaction to form a reversible imine bond, so that the graphene heating coating prepared in Example 2 has self-repairing function, maintains the integrity of the microscopic three-dimensional network structure, that is, maintains the integrity of the thermal conduction path, and thus can still exhibit excellent adhesion, moisture and heat resistance and thermal conductivity after being treated at 250°C for 1 hour, thereby improving the durability and heat resistance of the heating coating.

[0040] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A graphene heating paint, characterized in that: The raw materials include, by mass percentage, 1-30% nitrogen-doped graphene, 1-30% modified graphene nanoparticles, 5-15% methyl methacrylate, 5-15% styrene, 18-30% isooctyl acrylate, 0.5-5% methacrylic acid, 0.5-5% AMPS, 0.5-5% hydroxyethyl methacrylate, 0.5-3% crosslinking agent, 3% silane coupling agent, 0.5-1.5% emulsifier, 0.01-0.06% initiator, and the balance deionized water. The modified graphene nanoparticles are prepared by dispersing epoxy acrylate monomer and graphene oxide in water, stirring to form a suspension, continuing stirring and heating to 30-80°C, reacting for 1-2 hours, filtering, washing, and drying to obtain the modified graphene nanoparticles.

2. The graphene heating paint according to claim 1, characterized in that: The epoxy acrylate monomer is one or more of glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether.

3. The graphene heating paint according to claim 1, characterized in that: The preparation method of the nitrogen-doped graphene comprises dispersing graphene oxide in an alkaline solution, ultrasonically treating for 1-3 hours; hydrothermally reacting at 180-250° C. for 10-15 hours under nitrogen protection, cooling, washing, and freeze-drying to obtain the nitrogen-doped graphene.

4. The graphene heating paint according to claim 3, characterized in that: The alkaline solution is one or more of urea, hydrazine hydrate, ammonia water, and melamine.

5. The graphene heating paint according to claim 1, characterized in that: The mass ratio of the nitrogen-doped graphene to the modified graphene nanoparticles is 1:2-8.

6. The graphene heating paint according to claim 1, characterized in that: The crosslinking agent includes one or more of diacetone acrylamide, pentaerythritol triacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate, and N,N'-methylenebisacrylamide.

7. The graphene heating paint according to claim 1, characterized in that: The cross-linking agent is diacetone acrylamide.

8. The graphene heating paint according to claim 1, characterized in that: The silane coupling agent includes one or more of aminosilane coupling agent, epoxysilane coupling agent, methacryloxysilane coupling agent, mercaptosilane coupling agent, vinylsilane coupling agent, and alkylsilane coupling agent.

9. The graphene heating paint according to claim 1, characterized in that: The silane coupling agent is an aminosilane coupling agent.

10. The method for preparing the graphene heating paint according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Modified graphene nanoparticles, methyl methacrylate, styrene, isooctyl acrylate, methacrylic acid, hydroxyethyl methacrylate, AMPS, N,N'-methylenebisacrylamide, initiator, emulsifier and deionized water are mixed in sequence and stirred until uniformly dispersed to prepare a pre-emulsion; Step 2: Mix nitrogen-doped graphene and silane coupling agent, stir for 0.5-1h, continue to add 1 / 3 of the pre-emulsion, mix, and ultrasonicate for 10-30min to obtain a seed pre-emulsion; Step 3: Add seed pre-emulsion to the reactor, start stirring, heat to 45-85°C, react for 10-45 minutes to obtain seed emulsion, then add the remaining pre-emulsion to the reactor, add it within 0.5-3 hours, add redox initiator, continue to keep warm for 0.5-2 hours, cool down, discharge the material, and obtain the heating coating.

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