Insulating heat conductive material and method for producing same, and insulating heat conductive coating and method for producing same

Abstract

The application relates to an insulating and heat-conducting material and a preparation method thereof, and an insulating and heat-conducting coating and a preparation method thereof. The insulating and heat-conducting material comprises the following raw materials in parts by mass: 60-85 parts of a thermosetting resin, 15-30 parts of a heat-conducting filler, 25-40 parts of a diluent, and 0.1-15 parts of a curing agent; wherein the heat-conducting filler comprises a carbon material and a non-polar polymer loaded on the carbon material. The insulating and heat-conducting material has excellent heat-conducting performance and excellent electrical insulation performance, and is not easy to be broken down when applied to heat conduction and heat dissipation of electronic equipment, and has extremely high safety.

Description

Technical Field

[0001] The present application relates to the technical field of insulating thermally conductive materials, and in particular to an insulating thermally conductive material and a preparation method thereof, and an insulating thermally conductive coating and a preparation method thereof. Background Art

[0002] With the rapid development of the electronics industry in recent years, electronic equipment has continued to develop in the direction of miniaturization, high performance, integration and multi-function. However, at the same time, the power consumption and heat generation per unit area of ​​electronic equipment have also increased dramatically. If the large amount of heat generated cannot be transferred out in time, it will cause local areas of electronic equipment and components to overheat, thereby causing performance degradation or even damage to the electronic equipment and components.

[0003] Polymer materials, with their advantages of excellent mechanical properties, electrical insulation, chemical resistance, low cost, low density, and high processability, are widely used in the field of thermal conductivity and heat dissipation in electronic devices. To improve the thermal conductivity of polymer materials, thermally conductive fillers are typically added to the polymer matrix to prepare polymer-based thermal conductive materials. Traditional thermally conductive fillers primarily consist of carbon materials, such as carbon black, graphite, and graphene. These highly thermally conductive carbon materials often also exhibit excellent electrical conductivity, which reduces the electrical insulation performance of polymer-based thermal conductive materials, posing a significant risk when used in thermal conductivity and heat dissipation in electronic devices. Summary of the Invention

[0004] Based on this, it is necessary to provide an insulating thermally conductive material and a preparation method thereof, and an insulating thermally conductive coating and a preparation method thereof, so as to overcome the problem that traditional carbon materials have excellent electrical conductivity, which reduces the electrical insulation performance of polymer-based thermally conductive materials, resulting in very high risks when used in heat conduction and heat dissipation of electronic equipment.

[0005] The above-mentioned purpose of this application is achieved through the following technical solutions:

[0006] In a first aspect of the present application, an insulating thermally conductive material is provided, comprising the following raw materials in parts by weight:

[0007] 60~85 parts of thermosetting resin,

[0008] Thermal conductive filler 15~30 parts,

[0009] 25 to 40 parts of diluent, and

[0010] Curing agent 0.1~15 parts;

[0011] Wherein, the thermal conductive filler includes a carbon material and a non-polar polymer supported on the carbon material.

[0012] In one embodiment, in the thermally conductive filler, the mass ratio of the carbon material to the non-polar polymer is 1:(50-500).

[0013] In one embodiment, the non-polar polymer includes one or more of polyethylene, polypropylene, polystyrene, polyphenylene sulfide and polyvinylidene chloride.

[0014] In one embodiment, the non-polar polymer has a crystallinity of ≥60%.

[0015] In one embodiment, the carbon material includes one or more of graphene, carbon black, graphite, carbon nanotubes and carbon fibers.

[0016] In one embodiment, the thermosetting resin includes one or more of epoxy resin, bismaleimide resin, cyanate resin, thermosetting polyimide resin, unsaturated polyester resin, amino resin, phenolic resin and silicone resin.

[0017] In one embodiment, the diluent includes one or more of butyl glycidyl ether, ethylene glycol diglycidyl ether, and phenyl glycidyl ether.

[0018] In one embodiment, the curing agent includes one or more of an amine curing agent, an acid anhydride curing agent, a dicyandiamide curing agent, an imidazole curing agent, and a hydrazide curing agent.

[0019] In one embodiment, the insulating thermally conductive material further includes a promoter, an initiator and an auxiliary agent.

[0020] In a second aspect of the present application, a method for preparing an insulating thermally conductive material is provided, which comprises the following steps:

[0021] mixing a thermosetting resin and a diluent to prepare a resin solution;

[0022] Dispersing a thermally conductive filler in the resin solution to prepare a mixed slurry;

[0023] Adding a curing agent to the mixed slurry to prepare the insulating thermal conductive material;

[0024] Wherein, the thermal conductive filler includes a carbon material and a non-polar polymer supported on the carbon material.

[0025] In one embodiment, the method for preparing the thermally conductive filler comprises the following steps:

[0026] dissolving the non-polar polymer in an organic solvent to prepare a first mixed solution;

[0027] mixing the first mixed solution and the dispersion containing the carbon material to prepare a second mixed solution;

[0028] mixing the second mixed liquid and a nucleating agent to allow the non-polar polymer to crystallize on the surface of the carbon material to prepare a third mixed liquid;

[0029] The third mixed liquid is subjected to solid-liquid separation treatment to prepare the thermal conductive filler.

[0030] In one embodiment, the temperature for mixing the thermosetting resin and the diluent is 40° C. to 80° C.

[0031] In one embodiment, the temperature for dissolving the non-polar polymer in the organic solvent is 110° C. to 160° C.

[0032] In one embodiment, the temperature for crystallizing the non-polar polymer on the surface of the carbon material is 110° C. to 120° C.

[0033] In one embodiment, the mass ratio of the carbon material, the non-polar polymer and the nucleating agent is 1: (20-200): (0.002-0.03).

[0034] In one embodiment, before and / or after adding the curing agent to the mixed slurry, the following steps are further included: adding an accelerator, an initiator and an auxiliary agent to the mixed slurry.

[0035] In a third aspect of the present application, a method for preparing an insulating thermally conductive coating is provided, which comprises the following steps:

[0036] Performing a film-forming treatment on the insulating thermally conductive material described above, or performing a film-forming treatment on the insulating thermally conductive material prepared by the method for preparing the insulating thermally conductive material described above, to form a liquid film;

[0037] The liquid film is solidified to form the insulating thermal conductive coating.

[0038] In a fourth aspect of the present application, an insulating thermally conductive coating is provided, which is prepared using the above-mentioned method for preparing the insulating thermally conductive coating.

[0039] This application has the following beneficial effects:

[0040] The thermally conductive filler disclosed herein comprises a carbon material and a non-polar polymer supported on the carbon material. The non-polar polymer has a zero dipole moment and excellent electrical insulation properties. The non-polar polymer can be used to coat or modify the carbon material, reducing direct contact between the carbon materials and preventing them from forming a conductive network, thereby reducing the conductivity of the thermally conductive filler. By combining this thermally conductive filler with components such as a thermosetting resin, a diluent, and a curing agent in a specific ratio, the insulating thermally conductive material exhibits both excellent thermal conductivity and excellent electrical insulation properties. This makes it highly safe and resistant to breakdown when used in electronic devices for heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of a process for preparing an insulating thermally conductive material in one embodiment;

[0042] Figure 2 Schematic diagram of a process for preparing a thermally conductive filler in one embodiment;

[0043] Figure 3 is the SEM image of the graphene of Example 1;

[0044] Figure 4 This is the SEM image of the thermal conductive filler of Example 1. DETAILED DESCRIPTION

[0045] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] Heat transfer mainly relies on three methods: radiation, conduction and convection. At low temperatures, heat transfer in solid materials is mainly transmitted by heat conduction; for conductors such as metals, heat is mainly conducted through conductive carriers and lattice vibrations; in insulators such as polymers, lattice vibrations are the only heat transfer mechanism. The theoretical thermal conductivity of a perfect crystal can be obtained from the Debye equation: k=(c v νl) / 3, where k is the thermal conductivity, c vis the material's volumetric heat capacity, ν is the phonon group velocity, and l is the phonon mean free path. Therefore, the thermal conductivity of an insulator is influenced by a variety of factors, including the degree of crystallinity, the number of defects in the lattice, intercrystalline interactions, and the number of atoms in the lattice. Most polymers exhibit poor thermal conductivity due to poor crystallinity, a high proportion of amorphous regions, and low density, which hinder phonon propagation within the material.

[0049] To improve the thermal conductivity and heat dissipation capabilities of polymers, thermally conductive fillers are often added to the polymer matrix to create filled polymer-based thermal conductive materials. Among polymer-based thermal conductive materials, thermally conductive fillers are mostly carbon materials such as carbon black, graphite, and graphene. Graphene, hailed as the "king of new materials," possesses exceptional thermal conductivity due to its unique planar structure, capable of dissipating heat through radiation. Even at very low addition levels, it can enhance the thermal conductivity of polymer-based thermal conductive materials.

[0050] However, carbon materials such as graphene not only have high thermal conductivity, but also have very excellent electrical conductivity. While improving the thermal conductivity and heat dissipation capabilities of polymer-based thermal conductive materials, their electrical conductivity will also be improved. This means that the electrical insulation performance of polymer-based thermal conductive materials is reduced, which greatly limits the application scenarios of polymer-based thermal conductive materials. In particular, there are very large safety risks when used on charged surfaces that need to be insulated.

[0051] Based on this, the first aspect of the present application provides an insulating thermally conductive material to solve the problem that traditional carbon materials have excellent electrical conductivity, which reduces the electrical insulation performance of polymer-based thermally conductive materials, resulting in very high risks when used in heat conduction and heat dissipation of electronic equipment.

[0052] In some embodiments, the insulating thermally conductive material includes the following raw materials in parts by weight:

[0053] 60~85 parts of thermosetting resin,

[0054] Thermal conductive filler 15~30 parts,

[0055] 25 to 40 parts of diluent, and

[0056] Curing agent 0.1~15 parts;

[0057] The thermal conductive filler includes a carbon material and a non-polar polymer loaded on the carbon material.

[0058] It can be understood that a non-polar polymer refers to a polymer with zero dipole moment. The dipole moment of a polymer molecule can be obtained from the vector sum of bond distances. Usually, the vector sum of bond distances of structurally symmetrical molecules is zero, such as paraffin, polyethylene, polypropylene, polystyrene, and polytetrafluoroethylene.

[0059] The thermally conductive filler disclosed herein comprises a carbon material and a non-polar polymer supported on the carbon material. The non-polar polymer has a zero dipole moment and excellent electrical insulation properties. The non-polar polymer can be used to coat or modify the carbon material, reducing direct contact between the carbon materials and preventing them from forming a conductive network, thereby reducing the conductivity of the thermally conductive filler. By combining this thermally conductive filler with components such as a thermosetting resin, a diluent, and a curing agent in a specific ratio, the insulating thermally conductive material exhibits both excellent thermal conductivity and excellent electrical insulation properties. This makes it highly safe and resistant to breakdown when used in electronic devices for heat dissipation.

[0060] It is understood that the weight percentages of thermosetting resin include, but are not limited to, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, and 85 parts. The weight percentages of thermally conductive filler include, but are not limited to, 15 parts, 20 parts, 25 parts, and 30 parts. The weight percentages of diluent include, but are not limited to, 25 parts, 30 parts, 35 parts, and 40 parts. The weight percentages of curing agent include, but are not limited to, 0.1 parts, 0.5 parts, 1 part, 5 parts, 10 parts, and 15 parts.

[0061] Optionally, in the thermally conductive filler, the mass ratio of the carbon material to the non-polar polymer is 1:(50-500), for example, 1:50, 1:80, 1:100, 1:120, 1:150, 1:180, 1:200, 1:250, 1:300, 1:350, 1:400, 1:450, or 1:500. Preferably, in the thermally conductive filler, the mass ratio of the carbon material to the non-polar polymer is 1:(50-300). More preferably, in the thermally conductive filler, the mass ratio of the carbon material to the non-polar polymer is 1:(50-100).

[0062] The coating or modification of carbon materials by non-polar polymers will reduce the electrical conductivity of the conductive filler while increasing its thermal conductivity. Controlling the mass ratio of carbon materials and non-polar polymers can enable the thermally conductive filler to have both excellent thermal conductivity and good electrical insulation properties.

[0063] In some embodiments, the non-polar polymer includes one or more of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyphenylene sulfide (PPS), and polyvinylidene chloride (PVDC).

[0064] Non-polar polymers such as polyethylene and polypropylene have the characteristics of regular structure and very few or even no polar side groups, which can reduce the scattering of phonons during heat conduction, thereby improving the thermal conductivity and heat dissipation performance of thermal conductive fillers.

[0065] Optionally, the non-polar polymer is polyethylene (PE). Polyethylene has a well-structured, linear macromolecular backbone with no polar side groups, and has the highest thermal conductivity among many polymers. Polyethylene can include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-high molecular weight polyethylene (UHMWPE). Preferably, the non-polar polymer is HDPE.

[0066] Optionally, the non-polar polymer has a crystallinity of ≥60%, including but not limited to 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, 100%. Preferably, the non-polar polymer has a crystallinity of 80% to 98%.

[0067] Understandably, in non-polar polymers, regularly arranged regions are called crystalline regions, while disordered regions are called amorphous regions. The proportion of crystalline regions in a non-polar polymer is called crystallinity. Generally, polymers with a crystallinity of over 80% are called crystalline polymers. Compared to structurally disordered amorphous polymers, crystalline polymers have an ordered crystalline structure, resulting in better thermal conductivity and thermal stability. Increasing the crystallinity of non-polar polymers can improve their thermal conductivity, thereby simultaneously improving the electrical insulation and thermal conductivity of the thermally conductive filler.

[0068] In some embodiments, the carbon material includes one or more of graphene, carbon black, graphite, carbon nanotubes, and carbon fibers.

[0069] Optionally, the carbon material includes graphene. Graphene has good thermal conductivity due to its special planar structure and can significantly improve the thermal conductivity of the thermal conductive material at a low filling amount.

[0070] Optionally, the number of graphene layers is 1 to 6 layers, including but not limited to: 1 layer, 2 layers, 3 layers, 4 layers, 5 layers, and 6 layers.

[0071] Optionally, the thickness of the graphene layer is 0.1 nm to 5 nm, including but not limited to: 0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, and 5 nm.

[0072] Optionally, the diameter of the graphene sheet is 5 μm to 70 μm, including but not limited to: 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, and 70 μm.

[0073] Optionally, the specific surface area of ​​graphene is 300m 2 / g~1800m 2 / g, including but not limited to: 300m 2 / g、600m 2 / g、900m 2 / g、1200m 2 / g、1500m 2 / g、1800m 2 / g.

[0074] Optionally, the carbon material includes at least two of graphene, carbon black, graphite, carbon nanotubes, and carbon fibers. By combining at least two carbon materials, a more complete thermal conductivity pathway can be formed within the insulating thermally conductive material, thereby improving the thermal conductivity of the insulating thermally conductive material while also reducing the amount of thermally conductive filler used. For example, graphene and carbon black form a point-to-surface thermal conductivity pathway, while graphene and carbon fibers form a line-to-surface thermal conductivity pathway.

[0075] Preferably, the combination of at least two of the carbon materials includes but is not limited to: graphene and carbon black; graphene and graphite; graphene and carbon nanotubes; graphene and carbon fiber; graphene, carbon black and carbon nanotubes; graphene, carbon black and carbon fiber; graphene, carbon nanotubes and carbon fiber.

[0076] In some embodiments, the thermosetting resin includes one or more of epoxy resin, bismaleimide resin, cyanate resin, thermosetting polyimide resin, unsaturated polyester resin, amino resin, phenolic resin and silicone resin.

[0077] As can be understood, thermoset polymers refer to a class of high-molecular-weight polymer materials that undergo a cross-linking reaction under the influence of heat, pressure, light, or a curing agent, solidifying into an insoluble, infusible substance. These materials possess the advantages of high heat resistance and resistance to deformation under pressure. When used as a raw material for insulating and thermally conductive materials, thermoset resins are not yet cured and are generally solids with low molecular weight or viscous liquids. During the molding process, they can soften or flow, exhibiting a certain degree of plasticity. Furthermore, they undergo chemical reactions with components such as curing agents, initiators, and accelerators, causing cross-linking and curing, transforming into a non-softenable, non-flowable solid product.

[0078] In some embodiments, the thermosetting resin comprises an epoxy resin.

[0079] Epoxy resin has good weather resistance, excellent chemical stability, good heat resistance and electrical insulation. The film containing epoxy resin has good color retention and strong adhesion, so it has important applications in adhesives, electrical insulation materials and coatings.

[0080] Optionally, the epoxy resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, epoxidized olefin compound, heterocyclic epoxy resin and mixed epoxy resin. Preferably, the epoxy resin is bisphenol A epoxy resin.

[0081] In some embodiments, the diluent includes one or more of butyl glycidyl ether, ethylene glycol diglycidyl ether, and phenyl glycidyl ether.

[0082] All of the aforementioned diluents are reactive diluents, also known as functional monomers. They are small organic molecules containing polymerizable functional groups. The introduction of reactive diluents not only dissolves and dilutes thermosetting resins, adjusts system viscosity, and improves system fluidity and workability, but also participates in reactions during the curing process, increasing cure speed and the properties of the cured product while reducing volatile matter.

[0083] In some embodiments, the curing agent includes one or more of an amine curing agent, an acid anhydride curing agent, a dicyandiamide curing agent, an imidazole curing agent, and a hydrazide curing agent.

[0084] Optionally, the curing agent includes one or more of an amine curing agent and an acid anhydride curing agent.

[0085] Optionally, the amine curing agent includes one or more of polyamide, aliphatic amine, aromatic amine, alicyclic amine and polyether amine. Preferably, the amine curing agent is an organic boron amine compound, which is conducive to reducing the curing temperature and shortening the curing time.

[0086] Optionally, the anhydride curing agent includes one or more of dodecenylsuccinic anhydride, methyltetrahydrophthalic anhydride, and ketobenzimidazole. Preferably, the anhydride curing agent is methyltetrahydrophthalic anhydride, which is beneficial to lowering the curing temperature and shortening the curing time.

[0087] In some embodiments, the insulating thermally conductive material further includes a promoter, an initiator, and an auxiliary agent.

[0088] Adding accelerators and initiators to the curing system of thermosetting resins can further reduce the curing temperature and shorten the curing time, making the insulating thermal conductive material easier to process and avoiding the adverse effects of higher curing temperatures on electronic equipment.

[0089] In some embodiments, the accelerator includes one or more of a phosphine accelerator, a tertiary amine accelerator, a substituted urea accelerator, a phenol accelerator, and an imidazole accelerator.

[0090] Optionally, the phosphine accelerator includes one or more of triethylphosphine of boron trifluoride, triisopropylphosphine of boron trifluoride, trimethylphosphine, triphenylphosphine, a triphenylphosphine derivative, cyclotriphosphine and a phosphine amine compound.

[0091] Optionally, the tertiary amine accelerator includes one or more of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), benzyldimethylamine (BDMA), o-hydroxybenzyldimethylamine (DMP-10), triethylamine and triethanolamine.

[0092] Optionally, the substituted urea accelerator includes one or more of 3-phenyl-1,1-dimethylurea, 3-p-anisyl-1,1-dimethylurea, 3-p-nitrophenyl-1,1-dimethylurea and 4-phenyl-1,1-dimethylsemicarbazide.

[0093] Optionally, the phenolic accelerator includes one or more of phenol, resorcinol, o-cresol, nonylphenol and bisphenol A.

[0094] Optionally, the imidazole accelerator includes one or more of 2-phenylimidazole and 4-methylimidazole.

[0095] Preferably, the accelerator is a phosphine accelerator, and more preferably, the accelerator is triphenylphosphine.

[0096] In some embodiments, the initiator comprises a cationic initiator comprising one or more of a Lewis acid, an aromatic diazonium salt, a diaryliodonium salt, a triarylsulfonium salt, an alkylsulfonium salt, an iron arene salt, a sulfonyloxyketone, and a triarylsiloxane.

[0097] Cationic initiators can generate cationic active centers under ultraviolet radiation and initiate the polymerization of monomers such as epoxides and vinyl ethers. Compared with free radical initiators, cationic initiators have advantages such as being unaffected by oxygen, high initiation efficiency, high surface hardness, and low deep shrinkage.

[0098] Optionally, the cationic initiator includes a Lewis acid, such as quaternary ammonium-blocked hexafluoroantimonate and blocked fluoromethanesulfonic acid. Using a Lewis acid as an initiator can lower the curing temperature and increase the curing speed. It also linearizes the side chains of the cured product, reducing phonon scattering during heat transfer and further improving the thermal conductivity of the insulating thermally conductive material.

[0099] In some embodiments, the mass ratio of the thermosetting resin, the accelerator, and the initiator is 100:(0.1-6.5):(0.01-0.45). The mass ratio of the thermosetting resin to the accelerator is 100:(0.1-6.5), for example, 100:0.1, 100:0.5, 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:6.5; the mass ratio of the thermosetting resin to the initiator is 100:(0.1-4.5), for example, 100:0.01, 100:0.05, 100:0.1, 100:0.2, 100:0.3, 100:0.4, 100:0.45.

[0100] In some embodiments, the auxiliary agent includes one or more of a defoaming agent, a coupling agent, a leveling agent, and a dispersant.

[0101] Optionally, the defoaming agent includes one or more of an organosilicon defoaming agent, a polyether siloxane defoaming agent, and a fatty alcohol ethoxysiloxane defoaming agent.

[0102] Optionally, the coupling agent includes one or more of a silane coupling agent, a titanate coupling agent, a zirconate coupling agent, a phosphate coupling agent, and a chromium complex coupling agent. Preferably, the coupling agent is a silane coupling agent.

[0103] Optionally, the leveling agent includes a polyether-modified silicone leveling agent.

[0104] Optionally, the dispersant includes one or more of a polyurethane dispersant, a polyamide dispersant, and a polyacrylate dispersant.

[0105] Optionally, the mass proportions of the defoaming agent, coupling agent, leveling agent and dispersant in the insulating thermally conductive material are each independently 0.1% to 3%, including but not limited to: 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, and 3%.

[0106] In some embodiments, the insulating thermally conductive material includes the following raw materials in parts by weight:

[0107] 60~85 parts of thermosetting resin,

[0108] Thermal conductive filler 15~30 parts,

[0109] 25~40 parts of diluent,

[0110] 0.1~15 parts of curing agent,

[0111] 0.1~5 parts of initiator,

[0112] 0.1 to 3 parts of accelerator, and

[0113] 0.2~8 parts of additives.

[0114] Optionally, the curing temperature of the insulating thermally conductive material is 80°C~160°C, including but not limited to: 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, and 160°C.

[0115] Optionally, the curing time of the insulating thermally conductive material is 0.5h~3h, including but not limited to: 0.5h, 1h, 1.5h, 2h, 2.5h, and 3h.

[0116] In a second aspect of the present application, a method for preparing an insulating thermally conductive material is provided, which is used to prepare the insulating thermally conductive material described above.

[0117] See also Figure 1 , which is a flow chart of a method for preparing an insulating thermally conductive material in one embodiment, the method comprising the following steps:

[0118] S10: mixing a thermosetting resin and a diluent to prepare a resin solution;

[0119] S20: dispersing a thermally conductive filler in a resin solution to prepare a mixed slurry, wherein the thermally conductive filler includes a carbon material and a non-polar polymer supported on the carbon material.

[0120] S30: adding a curing agent to the mixed slurry to prepare an insulating thermal conductive material.

[0121] In some embodiments, in step S10, the temperature for mixing the thermosetting resin and the diluent is 40°C to 80°C, including but not limited to 40°C, 50°C, 60°C, 70°C, and 80°C.

[0122] Optionally, mixing the thermosetting resin and the diluent includes the following steps: heating the thermosetting resin at 40° C. to 80° C. to melt the thermosetting resin; adding the melted thermosetting resin to the diluent and stirring for 5 min to 10 min to obtain a resin solution.

[0123] It can be understood that thermosetting resin is a high molecular polymer material, and the molecular chains are chemically cross-linked together to form a rigid three-dimensional network structure. During the polymerization process, this cross-linked structure cannot be repeatedly processed and molded. Some thermosetting resins are high-viscosity liquids or solids at room temperature, and are not easy to form homogeneous solutions in diluents. Therefore, the thermosetting resin can be heated to melt or soften it, thereby accelerating the mixing speed of the thermosetting resin and the diluent.

[0124] See also Figure 2, which is a flow chart of a method for preparing a thermally conductive filler in one embodiment, the method comprising the following steps:

[0125] S21: dissolving a non-polar polymer in an organic solvent to prepare a first mixed solution;

[0126] S22: mixing the first mixed solution and the dispersion containing the carbon material to prepare a second mixed solution;

[0127] S23: mixing the second mixed solution and a nucleating agent to allow the non-polar polymer to crystallize on the surface of the carbon material to prepare a third mixed solution;

[0128] S24: performing solid-liquid separation on the third mixed liquid to prepare a thermally conductive filler.

[0129] Optionally, the mass ratio of the carbon material, the non-polar polymer, and the nucleating agent is 1:(50-300):(0.002-0.03). The mass ratio of the carbon material to the non-polar polymer is 1:(50-300), for example, 1:50, 1:80, 1:100, 1:120, 1:150, 1:180, 1:200, 1:250, and 1:300; and the mass ratio of the carbon material to the nucleating agent is 1:(0.002-0.03), for example, 1:0.002, 1:0.003, 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, and 1:0.03.

[0130] Optionally, the organic solvent includes one or more of toluene, xylene and trichloroethylene.

[0131] Optionally, the temperature for dissolving the non-polar polymer in the organic solvent is 110°C to 160°C, including but not limited to: 110°C, 120°C, 130°C, 140°C, 150°C, and 160°C.

[0132] Optionally, adding a dispersion containing carbon material to the first mixed liquid includes the following steps: mixing the carbon material and the organic solvent, performing ultrasonic dispersion treatment, and preparing a dispersion containing the carbon material; adding the dispersion containing the carbon material to the first mixed liquid, stirring at a speed of 800 rpm to 1500 rpm for 0.5 h to 1.5 h to prepare a second mixed liquid.

[0133] Optionally, the nucleating agent includes one or more of an α-type nucleating agent and a β-type nucleating agent. Preferably, the nucleating agent is an α-type nucleating agent, and the α-type nucleating agent includes one or more of dibenzylidene sorbitol (DBS), dibenzylidene sorbitol derivatives, aromatic phosphate nucleating agents, and substituted benzoate nucleating agents.

[0134] Understandably, nucleators are a type of functional additive for polymer modification. They improve the polymer's appearance, morphology, mechanical properties, and thermal conductivity by changing the polymer's crystallization behavior, accelerating the crystallization rate, increasing the degree of crystallinity, and promoting grain size refinement. They are suitable for improving polymer materials such as polyethylene and polypropylene. Among them, α-type nucleators refer to functional additives that can form short crystal nuclei on polymer molecular chains. Their molecular structure is similar to that of the polymer, making them compatible with polymer molecules and forming more and smaller crystal nuclei, thereby increasing the polymer's crystallization rate and crystal nucleus density. Common α-type nucleators include cyclic polymers and low-density polyethylene.

[0135] Optionally, the temperature for crystallizing the non-polar polymer on the carbon material surface is 110°C to 120°C, including but not limited to 110°C, 112°C, 114°C, 116°C, 118°C, and 120°C. The crystallization temperature and time affect the crystallinity of the non-polar polymer. Controlling the crystallization temperature and time can increase the crystallinity of the non-polar polymer and improve thermal conductivity.

[0136] Optionally, the method for performing solid-liquid separation treatment on the third mixed liquid includes one or more of suction filtration, filter press and centrifugation, preferably suction filtration, also known as vacuum filtration or reduced pressure filtration.

[0137] Optionally, the third mixed liquid is subjected to solid-liquid separation treatment, comprising the following steps: vacuum filtering the third mixed liquid to prepare filter residue; washing the filter residue multiple times to remove the organic solvent remaining on the surface of the filtrate; and drying the washed filter residue to prepare a thermal conductive filler.

[0138] The cleaning liquid for the multiple washing treatments of the filter residue is ethanol, preferably anhydrous ethanol. The temperature for drying the washed filter residue is 60° C. to 100° C., and the drying time is 20 min to 50 min.

[0139] Optionally, in step S20, dispersing the thermal conductive filler in the resin solution includes the following steps: adding a dispersant and a thermal conductive filler to the resin solution, and stirring at a rotation speed of 1500 rpm to 2500 rpm for 15 min to 30 min to form a uniformly dispersed mixed slurry.

[0140] Optionally, after dispersing the thermally conductive filler in the resin solution, the further step of cooling the mixed slurry to below 30°C is included. After cooling, the mixed slurry is at a lower temperature, and when components such as a curing agent are added, the thermosetting resin and curing agent do not rapidly undergo a curing reaction, thereby maintaining the stability and long-term storage properties of the insulating thermally conductive material.

[0141] In some embodiments, in step S30, before and / or after adding the curing agent to the mixed slurry, the following steps are further included: adding a accelerator, an initiator and an auxiliary agent to the mixed slurry.

[0142] Optionally, the auxiliary agent includes one or more of a defoaming agent, a coupling agent and a leveling agent.

[0143] Optionally, after adding the curing agent to the mixed slurry, the following steps are also included: adding a promoter, an initiator and a coupling agent to the mixed slurry, stirring at a speed of 800rpm~1200rom for 10min~30min, and adding a defoaming agent and a leveling agent at a speed of 200rpm~500rom, stirring for 10min~25min, to obtain the insulating heat dissipation graphene coating.

[0144] In a third aspect of the present application, a method for preparing an insulating thermally conductive coating is provided, which is the application of the above-mentioned insulating thermally conductive material in the field of coating.

[0145] In some embodiments, the method for preparing the insulating thermally conductive coating comprises the following steps:

[0146] Performing a film-forming treatment on the insulating thermally conductive material described above, or performing a film-forming treatment on the insulating thermally conductive material prepared according to the method for preparing the insulating thermally conductive material described above, to form a liquid film;

[0147] The liquid film is solidified to form an insulating thermal conductive coating.

[0148] Optionally, the insulating thermal conductive coating is formed on a substrate, and the substrate includes one or more of a metal substrate, a polymer substrate, a ceramic substrate, and a glass substrate.

[0149] Optionally, the film forming method includes one or more of a brush coating method, a blade coating method, a roller coating method, a spin coating method, a spray coating method and a screen printing method.

[0150] Optionally, the curing temperature is 80°C to 160°C, including but not limited to 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, and 160°C.

[0151] Optionally, the curing time is 0.5h~3h, including but not limited to: 0.5h, 1h, 1.5h, 2h, 2.5h, 3h.

[0152] In a third aspect of the present application, an insulating thermally conductive coating is provided, which is prepared using the above-mentioned method for preparing the insulating thermally conductive coating.

[0153] Optionally, the thickness of the insulating thermal conductive coating is 10 μm to 50 μm, including but not limited to: 10 μm, 20 μm, 30 μm, 40 μm, and 50 μm.

[0154] Optionally, the thermal conductivity of the insulating thermal conductive coating is 1.2 W / (m·K) to 1.6 W / (m·K).

[0155] Optionally, the resistivity of the insulating thermal conductive coating is 3.8×10 11 Ω·m~6×10 11 Ω·m.

[0156] Optionally, the breakdown voltage of the insulating thermal conductive coating is ≥25 kV / mm.

[0157] The present application is further described in detail below with reference to specific embodiments.

[0158] In the following specific examples and comparative examples, the raw materials used are commercially available unless otherwise specified; the instruments used are commercially available unless otherwise specified; and the processes used are routinely selected by those skilled in the art unless otherwise specified. The sources of some raw materials are as follows:

[0159] Bisphenol A epoxy resin: Phoenix brand 6101 and 618 (original brands E44 and E51 respectively); the epoxy equivalent weight of 6101 is 210g / mol~230g / mol, and the epoxy equivalent weight of 618 is 184g / mol~195g / mol. The mass ratio of 6101 to 618 is (1~3):1.

[0160] Bisphenol F type liquid epoxy resin: WXDIC epoxy resin 830S Bisphenol F type liquid epoxy resin, epoxy equivalent weight 165g / mol~175g / mol.

[0161] Graphene: XF001W produced by Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., with a sheet diameter of 0.5~5μm, a thickness of ≤0.8nm, and a specific surface area of ​​500m 2 / g~1000m 2 / g.

[0162] Carbon black: Cabot carbon black VXC72 produced by Borida (Dongguan) New Materials Co., Ltd., with a particle size of 30 μm and an oil absorption value of 192 cm 3 / 100g, with a specific surface area of ​​254m 2 / g.

[0163] Polyethylene: HDPE powder produced by Dongguan Juxinheng Rubber & Plastic Co., Ltd., particle size ≤10μm.

[0164] Polypropylene: Maoming Shihua PP150 produced by Dongguan Jiajia Plastic Raw Materials Co., Ltd.

[0165] Polyvinyl alcohol: polyvinyl alcohol from Merck Chemicals.

[0166] Diluent: AGE BLJ-C20 epoxy resin active diluent produced by Bailiju, which reduces the viscosity of epoxy resin.

[0167] n-Propanol: n-Propanol from Aladdin Chemical, 99.0% purity.

[0168] Xylene: Maclean's X821391, purity 99%.

[0169] Cationic initiator: Cationic initiator Vicbase TC3637 produced by Shenzhen KGI Applied Materials Co., Ltd., with an initiation temperature of 80°C.

[0170] Defoamer: BYK-A550 from BYK Chemical.

[0171] Leveling agent: BYK-346 from BYK Chemical.

[0172] Dispersant: ANTI-TERRA-204 from BYK.

[0173] Curing agent: Double Phoenix epoxy curing agent 594 produced by Wuxi Qianguang Chemical Raw Materials Co., Ltd., and T-188 epoxy resin cationic latent curing agent produced by Shanghai Huichuang Trading Co., Ltd.

[0174] Accelerator: Triphenylphosphine produced by Shandong Hongchuan Chemical Co., Ltd., purity ≥99.5%.

[0175] Coupling agent: KH-560 produced by Nanjing Xiangqian Chemical.

[0176] Example 1

[0177] (1) Preparation of thermal conductive filler:

[0178] Xylene and polyethylene were added to a three-necked flask and stirred at 150°C until the polyethylene was completely dissolved, yielding a first mixed solution. Graphene was dispersed in the xylene using ultrasonic dispersion to yield a graphene dispersion. The graphene dispersion was added to the three-necked flask and stirred at 1000 rpm for 1 hour to mix thoroughly, yielding a second mixed solution. An α-type nucleating agent was added to the second mixed solution, mixed thoroughly, and the mixture was rapidly cooled to 120°C for isothermal crystallization, allowing the polyethylene to crystallize on the graphene surface. This temperature was maintained for 8 minutes, yielding a third mixed solution. The third mixed solution was vacuum filtered to yield a filter residue. The filter residue was then washed five times with anhydrous ethanol to remove any residual xylene on the surface. The washed residue was dried at 50°C for 30 minutes to yield polyethylene-modified graphene, which served as the thermally conductive filler. The mass ratio of graphene, polyethylene, and α-type nucleating agent was 1:50:0.003. The polyethylene in the thermally conductive filler had a crystallinity of 96%.

[0179] (2) Preparation of insulating thermal conductive materials:

[0180] Prepare the raw materials according to the formula shown in Table 1; heat the bisphenol A epoxy resin at 60°C until it is melted, add the bisphenol A epoxy resin to the diluent, and stir for 10 minutes to obtain a resin solution; add a dispersant and a thermally conductive filler to the resin solution, and stir at a speed of 2000 rpm for 20 minutes to obtain a uniformly dispersed mixed slurry; cool the mixed slurry to below 30°C, add an initiator, a curing agent, a accelerator, and a coupling agent, and stir at a speed of 1000 rpm for 20 minutes, and add a defoaming agent and a leveling agent at a speed of 300 rpm, and continue stirring for 20 minutes to obtain an insulating thermally conductive material.

[0181] Table 1. Formulas of Examples 1 to 6 (Unit: parts by mass)

[0182]

[0183] Examples 2 to 6

[0184] The formulations of Examples 2 to 6 are shown in Table 1, and the preparation methods are basically the same as those of Example 1.

[0185] Example 7

[0186] The formula and preparation method of this embodiment are consistent with those of Example 1, except that the crystallinity of the polyethylene in the thermal conductive filler is 80%.

[0187] Example 8

[0188] The formula and preparation method of this embodiment are consistent with those of Example 1, except that the mass ratio of polyethylene to graphene in the thermal conductive filler is 500:1.

[0189] Example 9

[0190] The formula and preparation method of this embodiment are consistent with those of Example 1, except that the thermosetting resin is replaced by bisphenol A type epoxy resin with bisphenol F type liquid epoxy resin.

[0191] Example 10

[0192] The formula and preparation method of this embodiment are consistent with those of Example 1, except that the non-polar polymer in the thermally conductive filler is replaced by polypropylene of equal mass instead of polyethylene, that is, the thermally conductive filler is polypropylene-modified graphene.

[0193] Example 11

[0194] The formula and preparation method of this embodiment are consistent with those of Example 1, except that the thermal conductive filler includes two types, one is polyethylene-modified graphene and the other is polyethylene-modified carbon black, and the mass ratio of the two is 1:1.

[0195] Comparative Examples 1 to 7

[0196] The insulating thermally conductive materials of Comparative Examples 1 to 7 do not contain polyethylene-modified graphene, but are replaced with graphene and / or polyethylene. The formulations are shown in Table 2, and the preparation method is basically the same as step (2) of Example 1.

[0197] Comparative Example 8

[0198] The formula and preparation method of Comparative Example 8 are consistent with those of Example 1, except that the thermal conductive filler is graphene modified with a polar polymer, and the polar polymer is polyvinyl alcohol.

[0199] Table 2. Formulas of Comparative Examples 1 to 7 (Unit: parts by mass)

[0200]

[0201] Test Case

[0202] See also Figure 3 and Figure 4 ,in, Figure 3 is the SEM image of the graphene of Example 1 (magnification is 1000 times), Figure 4 The SEM image of the thermal conductive filler of Example 1 (magnification is 8000 times). Figure 3 It can be seen that graphene without polyethylene loading has a sheet structure, and the sheet surface is smooth and has no stripes; Figure 4 In the figure, the flake-like structure is graphene, and the stick-like stripes are polyethylene crystallized on the graphene surface, indicating that polyethylene has successfully crystallized on the graphene surface.

[0203] An insulating thermally conductive material was applied to the surface of an aluminum plate to form a liquid film. The film was dried at 80°C for 2.5 hours (160°C for 1.5 hours when no initiator was present) to completely dry the film, resulting in an insulating thermally conductive coating with a thickness of 50 μm, designated as the coated aluminum plate. The coated aluminum plate was subjected to the following tests, with the results shown in Table 3. The oven used was a TDTC-3060P oven manufactured by Wujiang Delta Oven Manufacturing Co., Ltd.; the constant temperature heating plate was a Torrey Pines programmable temperature heating plate manufactured by Shanghai Ruiyue Laboratory Equipment Co., Ltd.; the temperature recording device was a SIN-R200T manufactured by Lianchuang Instruments; and the withstand voltage tester was a 3153 withstand voltage tester manufactured by Hioki.

[0204] (1) Place the coated aluminum plate in an oven and heat it to 160°C at a heating rate of 3°C / min. Record the surface temperature of the coated aluminum plate over time. Under oven heating conditions, if the ambient temperature is higher than the surface temperature of the coated aluminum plate, the better the thermal conductivity of the coating, the shorter the time it takes for the surface temperature to reach the target temperature. That is, the closer the surface temperature of the coated aluminum plate is to that of the blank aluminum plate, the better the thermal conductivity.

[0205] (2) Place the coated aluminum plate on a constant temperature heating plate and heat it at 160°C for 1.5 hours. Record the surface temperature of the coated aluminum plate. Under the condition of constant temperature on the heating plate, if the ambient temperature is lower than the surface temperature of the coated aluminum plate, the better the heat dissipation performance of the coating, the faster the heat is released into the air, and the lower the surface temperature. In other words, the greater the difference in surface temperature between the coated aluminum plate and the blank aluminum plate, the better the heat dissipation performance.

[0206] (3) Use a voltage tester to test the breakdown voltage of the coated aluminum plate. The higher the breakdown voltage, the better the electrical insulation performance.

[0207] Table 3. Performance comparison of coated aluminum sheets (unit: °C)

[0208]

[0209] Table 3 shows that the insulating thermally conductive materials of Examples 1-11 exhibit excellent thermal conductivity. Under the same heating conditions, the surface temperature of the coated aluminum plates is very close to that of the bare aluminum plates. Similarly, the insulating thermally conductive materials exhibit excellent heat dissipation capabilities. Under the same constant temperature conditions, the surface temperature difference between the coated aluminum plates and the bare aluminum plates is significant. Furthermore, the insulating thermally conductive materials of Examples 1-6 exhibit excellent electrical insulation properties, resulting in higher breakdown voltages and improved safety for the corresponding coated aluminum plates.

[0210] The insulating and thermally conductive materials in Comparative Examples 1, 3, 5, and 6 all lack non-polar polymers loaded onto graphene, resulting in excellent electrical conductivity, which in turn leads to extremely low breakdown voltages and high safety risks. Comparative Examples 2 and 4 do not incorporate graphene, and Comparative Example 7 incorporates a small amount of graphene without a non-polar polymer, resulting in poor thermal conductivity and heat dissipation. Comparative Example 8 uses graphene loaded with a polar polymer as a thermally conductive filler, but its electrical insulation and heat dissipation performance are significantly reduced.

[0211] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0212] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patented invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims, and the specification may be used to interpret the content of the claims.

Claims

1. An insulating thermal conductive material, characterized in that: Including the following raw materials by weight: Wherein, the thermal conductive filler comprises a carbon material and a non-polar polymer supported on the carbon material, the non-polar polymer has a crystallinity of 80% to 98%; the non-polar polymer is high-density polyethylene or polypropylene; The preparation method of the thermally conductive filler comprises the following steps: dissolving the non-polar polymer in an organic solvent to prepare a first mixed solution; mixing the first mixed solution and the dispersion containing the carbon material to prepare a second mixed solution; mixing the second mixed liquid and a nucleating agent to allow the non-polar polymer to crystallize on the surface of the carbon material to prepare a third mixed liquid; The third mixed liquid is subjected to solid-liquid separation treatment to prepare the thermal conductive filler.

2. The insulating thermally conductive material according to claim 1, wherein: In the thermally conductive filler, the mass ratio of the carbon material to the non-polar polymer is 1:(50-500).

3. The insulating thermally conductive material according to claim 1, wherein One or more of the following conditions are met: (1) dissolving the non-polar polymer in the organic solvent at a temperature of 110° C. to 160° C.; (2) the temperature at which the non-polar polymer is crystallized on the surface of the carbon material is 110° C. to 120° C.; (3) The mass ratio of the carbon material, the non-polar polymer and the nucleating agent is 1:(20-200):(0.002-0.03).

4. The insulating thermally conductive material according to claim 1, wherein: One or more of the following conditions are met: (1) The carbon material includes one or more of graphene, carbon black, graphite, carbon nanotubes and carbon fibers; (2) The thermosetting resin includes one or more of epoxy resin, bismaleimide resin, cyanate resin, thermosetting polyimide resin, unsaturated polyester resin, amino resin, phenolic resin and silicone resin; (3) the diluent comprises one or more of butyl glycidyl ether, ethylene glycol diglycidyl ether and phenyl glycidyl ether; (4) The curing agent includes one or more of an amine curing agent, an acid anhydride curing agent, a dicyandiamide curing agent, an imidazole curing agent and a hydrazide curing agent.

5. The insulating thermally conductive material according to any one of claims 1 to 4, characterized in that: The insulating thermally conductive material further comprises a promoter, an initiator and an auxiliary agent.

6. The insulating thermally conductive material according to claim 5, wherein: The insulating thermally conductive material comprises the following raw materials in parts by mass:

7. A method for preparing the insulating thermally conductive material according to any one of claims 1 to 6, characterized in that: The following steps are involved: mixing a thermosetting resin and a diluent to prepare a resin solution; Dispersing a thermally conductive filler in the resin solution to prepare a mixed slurry; Adding a curing agent to the mixed slurry to prepare the insulating thermal conductive material; Wherein, the thermal conductive filler includes a carbon material and a non-polar polymer supported on the carbon material.

8. The method for preparing the insulating thermally conductive material according to claim 7, wherein: One or more of the following conditions are met: (1) The temperature of mixing thermosetting resin and diluent is 40℃~80℃; (2) Before and / or after adding the curing agent to the mixed slurry, the method further includes the following steps: adding a accelerator, an initiator and an auxiliary agent to the mixed slurry.

9. A method for preparing an insulating thermally conductive coating, characterized in that: The following steps are involved: Performing a film-forming treatment on the insulating thermally conductive material according to any one of claims 1 to 6, or performing a film-forming treatment on the insulating thermally conductive material prepared by the method for preparing the insulating thermally conductive material according to claim 7 or 8, to form a liquid film; The liquid film is solidified to form the insulating thermal conductive coating.

10. An insulating thermal conductive coating, characterized in that: The insulating thermally conductive coating is prepared using the preparation method of claim 9.

Images