High-thermal-conductivity filler composite insulation paper and preparation method thereof

Abstract

The invention discloses high-thermal-conductivity filler composite insulation paper and a preparation method thereof, and belongs to the technical field of thermal-conductivity insulation paper. The heat-conducting insulation paper comprises heat-conducting resin and insulation paper in a mass ratio of 100: (40-100), and the heat-conducting resin comprises 25%-35% by mass of heat-conducting filler. According to the invention, various heat-conducting fillers are compounded to obtain the high-heat-conducting powder, the modified BMI resin and the flexibilizer are used for preparing the high-strength and high-toughness bonding resin, and then the modified BMI resin and the flexibilizer are mixed to form a uniform resin layer and a heat-conducting path. After curing, the resin forms a stable three-dimensional cross-linked network structure, and the flexibilizer is interpenetrated in the three-dimensional cross-linked network structure to form an interpenetrating network which is tightly combined with the fibers. The heat-conducting insulation paper prepared by the invention is excellent in mechanical strength before curing and has high heat conductivity and high insulation stability after curing, and the method is simple, convenient, low in cost and suitable for high-temperature electrical equipment.

Description

Technical Field

[0001] This application relates to the field of thermally conductive insulating paper technology, and more specifically, to a high thermal conductivity filler composite insulating paper and its preparation method. Background Technology

[0002] Thermally conductive insulating paper, a novel composite material combining thermal conductivity and electrical insulation, has shown great application potential in high-tech fields such as power electronics, new energy, and 5G communications. As modern electronic devices and electrical equipment rapidly develop towards higher power density, greater integration, and miniaturization, the heat generated per unit volume within them increases dramatically, leading to a significant rise in operating temperature. Excessive temperature not only reduces the operating efficiency and reliability of electronic components but may even trigger thermal failure, severely impacting the safety and lifespan of the entire system. Therefore, efficient thermal management has become one of the key bottlenecks restricting the development of modern electronic and electrical technologies.

[0003] However, traditional insulating materials (such as ordinary insulating paper and epoxy resin boards) often struggle to simultaneously meet the dual requirements of thermal conductivity and insulation. While some materials possess excellent insulation properties, their extremely low thermal conductivity fails to meet the heat dissipation demands of high-power electronic devices; conversely, some materials with good thermal conductivity do not meet the safety standards of the electrical and electronic fields, making them unsuitable for practical applications. Therefore, developing thermally conductive insulating paper that combines high thermal conductivity with excellent insulation properties has become a current research hotspot and key direction in the field of electrical and electronic materials. Summary of the Invention

[0004] The purpose of this application is to provide a high thermal conductivity filler composite insulating paper and its preparation method. In the process of preparing thermally conductive insulating paper, a high content of thermally conductive filler is introduced to improve the thermal conductivity while ensuring that the processability, mechanical strength and dielectric strength of the insulating paper are not reduced, thereby producing a thermally conductive insulating paper with high thermal conductivity and excellent comprehensive performance.

[0005] To achieve the above objectives, this application provides a high thermal conductivity filler composite insulating paper, comprising a thermally conductive resin and insulating paper in a mass ratio of 100:40 to 100, wherein the thermally conductive resin comprises a thermally conductive filler with a mass fraction of 25% to 35%.

[0006] Furthermore, the thermally conductive resin includes an adhesive resin and a thermally conductive filler in a mass ratio of 50:100~200.

[0007] Furthermore, the adhesive resin includes a modified bismaleimide resin and a toughening agent in a mass ratio of 100:5 to 45.

[0008] Further, the modified bismaleimide resin comprises bismaleimide, bisphenol A diallyl ether, triallyl isocyanurate and t-butyl peroxy benzoate in a mass ratio of 100:30-50:5-20:0.5-1.

[0009] Further, the toughening agent comprises at least one of carboxyl-terminated butyl nitrile rubber, hydroxyl-terminated butyl nitrile rubber and epoxy-terminated butyl nitrile rubber.

[0010] Further, the heat-conductive filler comprises aluminum oxide and boron nitride, wherein the aluminum oxide comprises 100μm aluminum oxide, 50μm aluminum oxide, 10μm aluminum oxide, 5μm aluminum oxide and 300nm spherical aluminum oxide in a mass ratio of 80-100:40-60:10-30:10-30:3-15, and the boron nitride comprises 5μm hexagonal boron nitride, 5μm cubic boron nitride and 10nm hexagonal boron nitride in a mass ratio of 10-30:10-30:3-15.

[0011] Further, the insulation paper is PET insulation paper or aramid insulation paper, the thickness of the insulation paper is 0.05mm-1.5mm, the width of the insulation paper is 914mm-1280mm, and the gram weight of the insulation paper is 20g / cm 2 ~900g / cm 2 .

[0012] The application further discloses a preparation method of the high-heat-conductive filler composite insulation paper. The modified bismaleimide resin and the toughening agent are treated under stirring and temperature rising to obtain a bonding resin; The aluminum oxide and the boron nitride are treated by co-dissolution and co-blending to prepare a heat-conductive filler; The bonding resin is stirred and heated until the viscosity is reduced to 300mPa·s-400mPa·s, the heat-conductive filler is added and stirring is continued to obtain a heat-conductive resin; The heat-conductive resin is cooled and crushed to obtain a heat-conductive resin powder; The heat-conductive resin powder is scattered on the surface of the insulation paper at a preset rate, and the high-heat-conductive filler composite insulation paper is prepared after heat treatment and cooling.

[0013] Further, the heating temperature of the stirring and heating is 55℃-70℃, the holding time is 0.5h-1h, and the stirring rate is 250rpm-300rpm; during the process of cooling and crushing the heat-conductive resin, the temperature after cooling is 25℃-27℃, and the particle size after crushing is 80mesh-100mesh.

[0014] Further, the heat treatment includes three-stage drying treatment, specifically: the first-stage drying temperature is 60-90 DEG C, the drying duration is 0.5-5 min, the second-stage drying temperature is 130-180 DEG C, the drying duration is 1-10 min, and the third-stage drying temperature is 30-60 DEG C, the drying duration is 0.5-3 min.

[0015] Further, the heat treatment includes three-stage drying treatment, specifically: the first-stage drying temperature is 60-90 DEG C, the drying duration is 0.5-5 min, the second-stage drying temperature is 130-180 DEG C, the drying duration is 1-10 min, and the third-stage drying temperature is 30-60 DEG C, the drying duration is 0.5-3 min.

[0016] In summary, the application has the following advantages: 1. The high-thermal-conductivity filler composite insulation paper has scientific proportioning, and can simultaneously improve the thermal conductivity and insulation performance, wherein the mass fraction of the thermal-conductivity filler in the thermal-conductivity resin is controlled to be 25-35%, which can build an efficient thermal-conductivity foundation through a high proportion of the thermal-conductivity filler, and can rely on the synergistic effect of the insulation paper substrate and the resin system to avoid damage to the insulation performance caused by excessive filler, so as to realize accurate balance between high thermal conductivity and strong insulation performance, and meet the strict performance requirements of high-power electronic equipment on materials. In addition, the thermal-conductivity resin and the insulation paper form a closely combined composite structure, the interface compatibility of the thermal-conductivity filler and the resin, and the penetration and coating of the resin on the insulation paper fibers can improve the overall structural stability of the material, and the material can adapt to the installation and use requirements in different scenes such as motors and electric control systems, and break the limitation of single performance of traditional insulation paper.

[0017] 2. The preparation method of the high-thermal-conductivity filler composite insulation paper innovatively introduces a preset rate of thermal-conductivity resin powder scattering and heat treatment curing forming mode, replaces the traditional complex coating process, and does not need to rely on high-precision coating equipment, so that the thermal-conductivity resin can be uniformly covered on the surface of the insulation paper, and the resin can penetrate the fiber gap through heat treatment, and the production efficiency and product quality are considered, so as to provide an efficient process path for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the application. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creating labor intensity.

[0019] Figure 1 is a flowchart of the preparation method of the high-thermal-conductivity filler composite insulation paper proposed by the application. DETAILED DESCRIPTION

[0020] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0021] Traditional insulating materials (such as ordinary insulating paper, epoxy resin plate, etc.) often have difficulty in meeting the dual performance requirements of heat conduction and insulation. Some materials have good insulation performance, but the thermal conductivity is extremely low, which cannot meet the heat dissipation requirements of high-power electronic devices; and some materials with good thermal conductivity cannot meet the safety standards of the electronic and electrical field, and are difficult to apply in actual scenarios. Therefore, the development of heat-conducting insulating paper with high thermal conductivity and excellent insulation performance has become a research hotspot and key direction in the field of electronic and electrical materials.

[0022] Existing research shows that adding heat-conducting powder in the insulating paper matrix is the main technical means to improve the thermal conductivity of the insulating paper. By forming a heat-conducting path inside the insulating paper through the heat-conducting powder, the heat transfer efficiency in the insulating paper can be effectively improved, thereby improving the heat conduction performance of the insulating paper. However, in the actual preparation process, how to reasonably introduce the heat-conducting powder becomes the core factor restricting the improvement of the comprehensive performance of the insulating paper, and is also the main inducement for the bottleneck of the thermal conductivity of the heat-conducting insulating material. Specifically, when increasing the addition amount of the heat-conducting powder in order to pursue higher thermal conductivity, a series of problems will be caused: on the one hand, a high content of heat-conducting powder will significantly change the microstructure and interface bonding state of the insulating paper matrix, resulting in a significant decrease in the processing performance of the insulating paper, for example, the powder aggregation, uneven dispersion and other phenomena easily occur in the paper forming process, affecting the forming quality and production stability of the insulating paper; on the other hand, a high content of heat-conducting powder will also have a negative impact on the mechanical strength and dielectric strength of the insulating paper, as the addition amount of the heat-conducting powder increases, the mechanical performance indicators such as tensile strength and tear strength of the insulating paper will be significantly reduced, and the dielectric performance indicators such as dielectric constant and dielectric loss value will also deviate from the ideal range, resulting in that the mechanical stability and electrical insulation safety of the insulating paper cannot meet the use requirements of electronic and electrical equipment.

[0023] Therefore, the present application provides a high-thermal-conductivity filler composite insulating paper and a preparation method thereof, which can efficiently introduce a high content of heat-conducting filler without sacrificing or even improving the mechanical strength and dielectric strength of the insulating paper, thereby breaking through the technical bottleneck of the thermal conductivity of the insulating paper.

[0024] Specifically, in a first aspect, the application provides a high-thermal-conductivity filler composite insulating paper, comprising a thermal conductive resin and an insulating paper in a mass ratio of 100:40-100, wherein the thermal conductive resin comprises a thermal conductive filler in a mass fraction of 25%-35%. The thermal conductive resin serves as a thermal conductive filler carrier and an interfacial bonding agent, on one hand, to carry the thermal conductive filler and make it uniformly dispersed, avoiding the filler from falling off or agglomerating; on the other hand, to be tightly combined with the insulating paper fiber through its own adhesion, forming a stable structure after solidification, improving the overall mechanical strength of the material, and at the same time, its own insulation properties can assist in ensuring the dielectric properties of the composite paper. The insulating paper serves as a core base material, providing basic electrical insulation performance to prevent circuit short circuit or electric leakage; at the same time, its fiber structure has good mechanical support, which can enhance the tensile and tear resistance of the composite paper, avoiding the decline of the mechanical properties of the material caused by the addition of the thermal conductive filler, and is a basic guarantee for insulation and mechanical properties. The thermal conductive filler forms a continuous thermal conductive path in the thermal conductive resin, significantly improving the thermal conductivity of the composite paper, accelerating the heat transfer of electronic equipment during operation, and solving the problem of insufficient heat conduction of traditional insulating paper.

[0025] In the specific implementation, the thermal conductive resin comprises a bonding resin and a thermal conductive filler in a mass ratio of 50:100-200.

[0026] In the specific implementation, the bonding resin comprises a modified bismaleimide resin (BMI) and a toughening agent in a mass ratio of 100:5-45. The modified BMI system and the toughening agent system are mixed to obtain a bonding resin with high strength and high toughness. The toughening agent is mixed with the modified BMI resin at a low temperature (55-65°C) and does not participate in crosslinking reaction but is uniformly dispersed in the resin system to form an interpenetrating polymer network (IPN structure), further improving the toughness and impact resistance of the bonding resin, avoiding the fracture of the thermal insulating paper under external force, and at the same time maintaining the flexibility of the resin at room temperature, facilitating storage and transportation.

[0027] In the embodiment, the modified bismaleimide resin comprises bismaleimide, bisphenol A diallyl ether, triallyl isocyanurate and t-butyl peroxy benzoate in a mass ratio of 100:30-50:5-20:0.5-1. The bismaleimide resin is the main skeleton material, which provides excellent high-temperature resistance and dielectric insulation. The active groups in the molecular structure of the bismaleimide resin provide the basis for the subsequent cross-linking reaction and are the key to guarantee the core performance of the adhesive resin, such as high-temperature stability and insulation. The bisphenol A diallyl ether reacts with the bismaleimide resin to introduce flexible ether bonds into the molecular chain of the prepolymer, thereby improving the brittleness of the resin and improving the processing fluidity of the resin, which lays the foundation for the subsequent cross-linking reaction with triallyl isocyanurate and the mixing of the toughening agent. The triallyl isocyanurate as a cross-linking reinforcing agent contains multiple unsaturated double bonds, which reacts with the prepolymer to form a more compact three-dimensional cross-linked network structure, thereby significantly improving the mechanical strength (such as tensile strength) and structural stability of the adhesive resin, and avoiding deformation of the resin during the subsequent curing process. The t-butyl peroxy benzoate as a curing initiator decomposes to generate free radicals at a specific temperature, thereby initiating the cross-linking and curing reaction of the resin system, accurately controlling the curing rate, ensuring that the resin is fully cured during the subsequent heat treatment process of the heat-conducting and insulating paper, and avoiding the occurrence of bubbles and defects in the resin due to uncontrolled reaction of the initiator.

[0028] In the embodiment, the toughening agent comprises at least one of carboxyl-terminated nitrile rubber, hydroxyl-terminated nitrile rubber and epoxy-terminated nitrile rubber.

[0029] In the embodiment, the heat-conducting filler comprises aluminum oxide and boron nitride. The aluminum oxide comprises 100 μm aluminum oxide, 50 μm aluminum oxide, 10 μm aluminum oxide, 5 μm aluminum oxide and 300 nm spherical aluminum oxide in a mass ratio of 80-100:40-60:10-30:10-30:3-15. The boron nitride comprises 5 μm hexagonal boron nitride, 5 μm cubic boron nitride and 10 nm hexagonal boron nitride in a mass ratio of 10-30:10-30:3-15. The small-particle-size aluminum oxide of the present application can accurately fill the large-particle-size gaps to form a compact heat-conducting structure with micron skeletons and nanometer filling, thereby reducing the heat-conducting blind area. The boron nitride is compounded with 5 μm hexagonal boron nitride (insulation enhancement), 5 μm cubic boron nitride (high heat conductivity) and 10 nm hexagonal boron nitride (gap filling), which not only improves the heat conductivity coefficient by using cubic boron nitride, but also enhances the insulation and interface bonding force by using hexagonal boron nitride, thereby achieving the synergistic effect of high heat conductivity, strong insulation and low defects, and avoiding the problems of discontinuous heat-conducting path or insulation failure caused by single particle size / type filler.

[0030] In the embodiment, the insulating paper is PET insulating paper or aramid insulating paper. The thickness of the insulating paper is 0.05-1.5 mm, the width is 914-1280 mm, and the grammage is 20-100 g / m2. 2~900g / cm 2 In this application, the fibrous pore structure of the PET / aramid insulating paper allows for full penetration and bonding with the adhesive resin (which becomes viscous after heating). At the same time, it facilitates the entry of thermally conductive fillers (especially nano-sized fillers) into the pores to form a continuous thermally conductive pathway. This avoids the problem of insufficient resin penetration and decreased thermal conductivity caused by excessively high substrate density, thus ensuring the structural integrity and performance uniformity of the final composite insulating paper.

[0031] Secondly, based on a general inventive concept, such as Figure 1 As shown, this application also discloses a method for preparing a high thermal conductivity filler composite insulating paper, comprising the following steps: S1. Modified bismaleimide resin and toughening agent are heated under stirring to obtain adhesive resin.

[0032] In a specific embodiment, the adhesive resin is prepared by the following method: S101. Add bismaleimide resin and bisphenol A dielyl ether to the reaction vessel, heat to 150℃~160℃, and keep warm for 70min~90min to obtain the prepolymer. S102. Add triallyl isocyanurate to the prepolymer, and continuously heat to 165℃~175℃, hold for 25min~35min to obtain the first intermediate; S103, cool to room temperature, then add tert-butyl peroxide to the first intermediate and stir for 25 min to 40 min to obtain modified BMI resin (i.e., modified bismaleimide resin). S104. After mixing the modified BMI resin and toughening agent, heat the mixture to 55℃~65℃ and hold it for 50min~70min to obtain the bonding resin.

[0033] In the above-described method for preparing the adhesive resin, bismaleimide and bisphenol A dielyl ether are first allowed to fully react to generate a prepolymer. Then, triallyl isocyanurate is added to strengthen the crosslinking. Finally, the toughening agent is mixed at a low temperature to avoid high-temperature damage to the toughening agent structure. The entire process is free from reaction disturbances or performance loss, ensuring consistent performance of each batch of adhesive resin. The prepared adhesive resin exhibits both room temperature stability and heating fluidity. At room temperature, it remains solid due to the synergistic effect of the curing initiator and toughening agent, facilitating storage and pulverization. When heated to a specific temperature (e.g., 160°C), it quickly reaches a suitable viscosity, allowing for efficient penetration into insulating paper fibers and dispersion of thermally conductive fillers. No additional process parameter adjustments are required, making it suitable for the powdering-heat treatment molding process of thermally conductive insulating paper, reducing production time.

[0034] S2. Thermally conductive fillers are prepared by co-solution and blending of alumina and boron nitride.

[0035] In a specific embodiment, the co-solution and blending treatment includes the following steps: dissolving alumina and boron nitride in a solvent, and then mixing and grinding them at high speed using a nano-grinding mill to obtain a mixture; drying the mixture at 78℃~82℃ to remove the solvent, followed by crushing to obtain a thermally conductive filler in powder form. Preferably, the solvent is one or a combination of ethanol, N,N-dimethylformamide, N,N-dimethylacetamide, and tetrahydrofuran. The high-speed mixing speed is 500rpm~3000rpm, and the grinding time is 0.5h~5h. Preferably, the particle size of the crushed powder is 80 mesh~100 mesh.

[0036] S3. Stir and heat the adhesive resin until the viscosity decreases to 300 mPa·s~400 mPa·s, add the thermally conductive filler and continue stirring to obtain the thermally conductive resin.

[0037] In a specific embodiment, the heating temperature for stirring and heating is 55℃~70℃, the holding time is 0.5h~1h, the stirring rate is 250rpm~300rpm, and the stirring method is pneumatic stirring or mechanical stirring.

[0038] S4. Cool and pulverize the thermally conductive resin to obtain thermally conductive resin powder.

[0039] In a specific embodiment, during the cooling and pulverizing process of the thermally conductive resin, the temperature after cooling is 25℃~27℃, and the particle size after pulverization is 80 mesh~100 mesh.

[0040] S5. Sprinkle thermally conductive resin powder onto the surface of insulating paper at a preset rate, and after heat treatment and cooling, obtain high thermal conductivity filler composite insulating paper.

[0041] In a specific embodiment, the heat treatment includes three stages of drying: the first stage drying temperature is 60℃~90℃, and the drying time is 0.5min~5min; the second stage drying temperature is 130℃~180℃, and the drying time is 1min~10min; the third stage drying temperature is 30℃~60℃, and the drying time is 0.5min~3min. In the drying oven, the resin softens upon heating and carries the thermally conductive powder into the pores of the insulating paper.

[0042] In a specific embodiment, the thermally conductive resin powder is sprinkled onto the surface of the insulating paper at a preset rate, including: putting the thermally conductive resin powder into the hopper of the powder spreader and sprinkling it onto the surface of the insulating paper at a speed of 1 m / min to 3 m / min.

[0043] In summary, this application, through the research and development of component formulations and innovation in preparation processes, effectively solves the technical challenge of simultaneously achieving high thermal conductivity and excellent mechanical and dielectric strength in the existing preparation of thermally conductive insulating paper. Compared with existing technologies, it has at least the following significant beneficial effects: (1) Significantly improve the comprehensive mechanical properties and structural stability of heat-conducting insulating paper The application innovatively uses a modified BMI system (bismaleimide resin, bisphenol A diallyl ether, triallyl isocyanurate) and a toughening agent system to form a bonding resin, and through precise control of chemical reactions and microstructure, the mechanical properties are broken through. On the one hand, the bismaleimide resin, bisphenol A diallyl ether and triallyl isocyanurate form a star-shaped pre-polymer through allyl addition reaction, which further crosslinks to form a stable three-dimensional crosslinked network structure during curing, providing excellent structural support and rigidity for the heat-conducting insulating paper, greatly improving the tensile, tear resistance and other static mechanical properties of the material. On the other hand, the toughening agent does not participate in chemical reactions during curing, but is uniformly inserted into the three-dimensional crosslinked network to form an interpenetrating polymer network (IPN structure). When the material is subjected to external force impact or deformation, the IPN structure can absorb external energy through its own deformation and energy dissipation, effectively relieving stress concentration, significantly improving the toughness and impact resistance of the heat-conducting insulating paper, avoiding performance failure due to brittle fracture, and ensuring its structural stability under complex working conditions.

[0044] (2) Optimize the processing and storage performance of the bonding resin The bonding resin of the application has precise controllable thermal physical properties, with a stable softening point of about 90°C. When heated to 160°C, it can quickly change to a viscous state with suitable flowability. During preparation, when the temperature reaches 160°C, the bonding resin can fully penetrate into the interior of the substrate fibers, while driving a high proportion of heat-conducting powder to disperse uniformly, ensuring the close combination of heat-conducting powder and substrate fibers. At room temperature, the bonding resin can maintain a stable solid state and certain toughness, not only facilitating long-term storage of the material (effectively avoiding problems such as resin sticking and deterioration at room temperature), but also reducing the risk of damage during transportation, significantly improving the operational convenience and process stability during production, and laying a good foundation for large-scale production.

[0045] (3) Build an efficient heat-conducting path, taking into account excellent insulation performance and high-temperature applicability The present application successfully constructs a high-efficiency and stable thermal-conducting and insulating system through the synergistic process of multiple sizes and properties of fillers and the penetration and curing of thermosetting resin. On the one hand, the thermal-conducting powder formed by the compounding of multiple sizes and properties of fillers, driven by the adhesive resin, not only can form a continuous thermal-conducting layer on the surface of the substrate, but also can penetrate into the interstitial space of the fibers, utilize the synergistic filling effect of fillers of different sizes to reduce the thermal-conducting blind area, and form a three-dimensional thermal-conducting path throughout the material, greatly improving the thermal-conductivity of the thermal-conducting and insulating paper, and effectively solving the problem of discontinuous thermal-conducting path and low thermal-conducting efficiency of the traditional single-size filler. On the other hand, the three-dimensional crosslinked resin network after curing has excellent dielectric properties, and its compact molecular structure can effectively block the migration of electric charges. Meanwhile, the uniform dispersion of the high-proportion thermal-conducting powder does not damage the insulating properties of the resin, but rather further optimizes the dielectric properties through the interface bonding effect of the resin and the powder, ensuring that the thermal-conducting and insulating paper has high dielectric strength and low dielectric loss after curing, meeting the insulating safety standards in the electronic and electrical fields. In addition, the three-dimensional crosslinked network structure after curing also endows the material with excellent high-temperature stability, which can maintain the stability of structure and performance in high-temperature environment, and is suitable for electrical equipment in high-temperature working conditions such as motors and electric control systems of new energy vehicles, thereby widening the application scenarios of the thermal-conducting and insulating paper.

[0046] (4) Reduces the preparation cost and improves the economic benefit The preparation method of the present application has significant economic advantages. On the one hand, the selected thermal-conducting filler is a compounding system of multiple conventional sizes and properties of fillers, which does not need to rely on high-priced special fillers, greatly reducing the raw material cost. On the other hand, the preparation process is based on the simplified process of the formed insulating paper and the resin penetration and curing, which does not need complex special equipment, and the operation steps are simple, which can effectively shorten the production cycle, reduce the equipment investment and energy consumption cost. At the same time, the thermal-conducting and insulating paper prepared by this method has excellent comprehensive performance, which can meet the core needs of high-power-density and small-sized electronic equipment, has wide market application prospects, and takes into account the advanced technology and economic feasibility, providing strong support for industrialization promotion, and has high practical value and significant economic benefit.

[0047] The above technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0048] The BMI used in the following examples is N,N'-(methylene diphenyl) bismaleimide, purchased from Shandong Minghoudegao Polymer Material Co., Ltd.

[0049] Example 1 The present embodiment provides a high-thermal-conducting filler composite insulating paper, which is prepared by the following method: (1) Preparation of modified BMI resin 5000g BMI, 2200g bisphenol A bisallyl ether were added into a reaction container, and the temperature was raised to 155℃ and kept for 80min to obtain a prepolymer.

[0050] Then 550g triallyl isocyanurate was added into the prepolymer, and the temperature was raised to 170℃ and kept for 30min. Subsequently, the temperature was lowered to room temperature, 5g t-butyl peroxybenzoate was added, and stirred for 0.5h to obtain a modified BMI resin.

[0051] (2) Preparation of adhesive resin 5000g modified BMI resin and 1500g epoxy-terminated butyronitrile rubber were added into a stirring container, and the temperature was raised to 60℃ and kept for 1h to obtain an adhesive resin.

[0052] (3) Preparation of thermal conductive filler 800g of alumina with a particle size of 100μm, 480g of alumina with a particle size of 50μm, 240g of alumina with a particle size of 10μm, 240g of alumina with a particle size of 5μm, 230g of hexagonal boron nitride with a particle size of 5μm, 225g of cubic boron nitride with a particle size of 5μm, 50g of spherical alumina with a particle size of 300nm, and 50g of hexagonal boron nitride with a particle size of 100nm were added into an ethanol solvent, and a mixture was obtained after high-speed mixing and grinding by a nano sand mill at a speed of 3000rad / min for 1h. After drying the mixture at 80℃ to remove the solvent, a crusher was used to crush the mixture, and the particle size of the crushed mixture was 100 mesh to obtain a thermal conductive filler powder.

[0053] The thermal conductivity of the obtained thermal conductive filler powder was tested, and the thermal conductivity was 30W / m·K, indicating that the micro-nano structure is beneficial to improving the thermal conductivity of the material.

[0054] (4) Preparation of thermal conductive resin powder 5000g of the adhesive resin prepared in step (2) and 11000g of the thermal conductive filler powder prepared in step (3) were weighed into a stirring container, 16000g of DMF (N,N-dimethylformamide, accounting for 100% of the total mass of the adhesive resin and the thermal conductive filler) was added, and the temperature was raised to 60℃ and stirred for 3h. After stirring, the resin was poured into a vacuum tank, the temperature was raised to 80℃ and vacuumized, and the solvent was quickly discharged. When there was no liquid flowing out of the condenser outlet, the temperature was lowered to 25℃ to obtain a block solid, and then the block solid resin was put into a crushing device to obtain a thermal conductive resin powder with a particle size of 100 mesh.

[0055] (5) Preparation of thermal conductive insulation paper The prepared heat-conducting resin powder is added to the hopper of the powdering machine, the electrostatic voltage is 5 kV, the output ratio is 99%, and the powder is scattered on the insulating paper at a vehicle speed of 2 m / min. Then they are put into the oven together, first dried at 80℃ for 2 min, then dried at 165℃ for 3 min, and then dried at 60℃ for 1 min. A traction force of 10 kg is applied for processing, and then the product is wound to obtain a heat-conducting insulating paper, and the thermal conductivity of the heat-conducting insulating paper is 0.41 W / m·K.

[0056] Example 2 The difference between this example and Example 1 is that the mass of the adhesive resin in step (4) is 5000 g, the mass of the heat-conducting filler powder is 13000 g, and the mass of DMF is 18000 g. The remaining process steps and parameter settings are the same as those of Example 1. The mechanical and electrical performance tests of the obtained heat-conducting insulating paper are shown in Example 2 in Table 1 below.

[0057] Example 3 The difference between this example and Example 1 is that the mass of the adhesive resin in step (4) is 5000 g, the mass of the heat-conducting filler powder is 15000 g, and the mass of DMF is 20000 g. The remaining process steps and parameter settings are the same as those of Example 1. The mechanical and electrical performance tests of the obtained heat-conducting insulating paper are shown in Example 3 in Table 1 below.

[0058] Table 1 Performance test results of heat-conducting insulating paper in Examples 1-3

[0059] As can be seen from Table 1, within the scope of the present application, appropriately increasing the proportion of heat-conducting fillers can significantly improve the heat-conducting performance of the heat-conducting insulating paper, but will also cause the tensile strength of the insulating paper solidification to decrease.

[0060] Example 4 The difference between this example and Example 1 is that in step (2), 5000 g of modified BMI resin and 2250 g of epoxy-terminated nitrile rubber are added to the stirring container, heated to 60℃ and kept for 1 h to obtain the adhesive resin, and the remaining process steps and parameter settings are the same as those of Example 1. The mechanical and electrical performance tests of the obtained heat-conducting insulating paper solidification are shown in Example 4 in Table 2 below.

[0061] Table 2 Performance test results of heat-conducting insulating paper in Examples 1 and 4

[0062] As shown in Table 2, the content of the toughening agent in the bonding resin (increased from 1500 g in Example 1 to 2250 g in Example 4) is increased, which can significantly increase the tensile strength of the heat-conducting insulation paper.

[0063] Example 5 Example 5 is different from Example 1 in that the amount of 100 μm alumina in the heat-conducting filler in step (3) is 900 g, and the amount of 300 nm alumina is 40 g, and the rest of the process steps and parameter settings are the same as those in Example 1. The obtained heat-conducting insulation paper is tested for mechanical and electrical properties, and the results are shown in Example 5 in Table 3 below.

[0064] Example 6 Example 6 is different from Example 1 in that the content of the heat-conducting filler in step (3) is changed, wherein the amount of 100 μm alumina is increased to 1000 g, and the amount of 300 nm alumina is 30 g, and the rest of the filler ratio remains unchanged, and the process steps and parameter settings are the same as those in Example 1. The obtained heat-conducting insulation paper is tested for mechanical and electrical properties, and the results are shown in Example 6 in Table 3 below.

[0065] Table 3 Performance test results of heat-conducting insulation paper in Examples 1, 5-6

[0066] As shown in Table 3, increasing the proportion of large-particle-size alumina material can improve the thermal conductivity of the heat-conducting insulation paper, but can significantly reduce the mechanical strength.

[0067] Example 7 Example 7 is different from Example 1 in that the amount of the heat-conducting filler in step (3) is changed, specifically: 1000 g of 100 μm alumina, 260 g of 5 μm hexagonal boron nitride, 50 g of 300 nm spherical alumina, and 50 g of 100 nm spherical hexagonal boron nitride, and the rest of the filler ratio remains unchanged, and the rest of the process steps and parameter settings are the same as those in Example 1. The thermal conductivity of the obtained heat-conducting powder is tested, and the result is 35 W / m·K, indicating that increasing the proportion of micron cubic boron nitride in the formula can improve the thermal conductivity of the heat-conducting insulation paper. The obtained heat-conducting insulation paper solid is tested for mechanical and electrical properties, and the results are shown in Example 7 in Table 4 below.

[0068] Example 8 Example 8 differs from Example 1 in that the amount of the heat-conducting filler in step (3) is changed, specifically: 1000 g of 100 pm alumina, 230 g of cubic boron nitride with a particle size of 5 pm, 50 g of spherical alumina with a particle size of 300 nm, and 40 g of spherical hexagonal boron nitride with a particle size of 100 nm, and the rest of the filler ratio remains unchanged, and the rest of the process steps and parameter settings are the same as those of Example 1. The thermal conductivity of the obtained heat-conducting powder is tested, and the result is 28.6 W / m·K, indicating that reducing the proportion of nanometer spherical boron nitride in the formula will reduce the density and thermal conductivity of the heat-conducting insulation paper, and the insulation performance will also decrease. The mechanical and electrical performance of the obtained heat-conducting insulation paper solidification is tested, and the results are shown in Example 8 in Table 4 below.

[0069] Example 9 Example 9 differs from Example 1 in that the amount of the heat-conducting filler in step (3) is changed, specifically: 1000 g of 100 pm alumina, 230 g of cubic boron nitride with a particle size of 5 pm, 80 g of spherical alumina with a particle size of 300 nm, and 50 g of spherical hexagonal boron nitride with a particle size of 100 nm, and the rest of the process steps and parameter settings are the same as those of Example 1. The thermal conductivity of the obtained heat-conducting powder is tested, and the result is 32.1 W / m·K, indicating that increasing the proportion of nanometer spherical alumina in the formula can improve the density and thermal conductivity of the heat-conducting insulation paper, but will reduce the insulation performance. The mechanical and electrical performance of the obtained heat-conducting insulation paper solidification is tested, and the results are shown in Example 9 in Table 4 below.

[0070] Example 10 Example 10 differs from Example 1 in that the ratio of the heat-conducting fillers in step (3) is changed, specifically: 1000 g of 100 pm alumina, 230 g of cubic boron nitride with a particle size of 5 pm, 50 g of spherical alumina with a particle size of 300 nm, and 80 g of spherical hexagonal boron nitride with a particle size of 100 nm, and the rest of the filler ratio remains unchanged, and the rest of the process steps and parameter settings are the same as those of Example 1. The thermal conductivity of the obtained heat-conducting powder is tested, and the result is 33.3 W / m·K, indicating that nanometer spherical boron nitride has a better effect on improving the thermal conductivity of the heat-conducting insulation paper than nanometer spherical alumina in the formula. The mechanical and electrical performance of the obtained heat-conducting insulation paper solidification is tested, and the results are shown in Example 10 in Table 4 below. It should be noted that all the examples in the present application can achieve the purpose of high thermal conductivity and high insulation stability, and the setting of the examples is to illustrate the function of different components and the role played in the heat-conducting insulation paper.

[0071] Table 4 Performance test results of the heat-conducting insulation paper in Examples 1 and 7-10

[0072] It can be seen that the addition of aluminum oxide in the heat-conductive filler can improve the insulation performance of the heat-conductive insulation paper, and the addition of boron nitride can improve the heat-conductive performance of the heat-conductive insulation paper.

[0073] The present application realizes 0.41 W / m K higher thermal conductivity, while maintaining the longitudinal tensile strength at 80 N / 10 mm and the breakdown field strength at 22 kV / mm, truly realizing the balance of the three. At the same time, the composition of the heat-conductive filler (multi-particle size, multi-type compounding) of the present application is highly compatible with the resin penetration-powder forming process, the multi-particle size powder is easy to mix evenly with the adhesive resin, and the 100-mesh powder formed after crushing has good flowability and is easy to spread; during the resin penetration process, the small-particle-size powder enters the gap between the insulation paper fibers with the resin, and forms a continuous heat-conductive path with the large-particle-size powder (the structure is stable after curing).

[0074] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0075] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to cover the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0076] Finally, it should also be noted that in this document, relational terms such as first and second and the like can only be used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed or inherent to such a process, method, article or terminal device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or terminal device including the element.

[0077] The principles and implementation manners of the present application are described by using specific examples in the present text, and the above example descriptions are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manners and application ranges will have changes, and on the basis of the above, the content of the present description should not be understood as the limitation of the present application.

Claims

1. A high thermal conductive filler composite insulation paper, characterized in that, The heat-conducting resin comprises heat-conducting resin and insulating paper in a mass ratio of 100:40-100, wherein the heat-conducting resin comprises heat-conducting filler in a mass fraction of 25%-35%.

2. The high thermal conductive filler composite insulation paper according to claim 1, characterized in that, The heat-conducting resin comprises heat-conducting resin and insulating paper in a mass ratio of 100:40-100, wherein the heat-conducting resin comprises heat-conducting filler in a mass fraction of 25%-35%.

3. The high thermal conductive filler composite insulation paper according to claim 2, characterized in that, The adhesive resin comprises modified bismaleimide resin and toughening agent in a mass ratio of 100:5-45.

4. The high thermal conductive filler composite insulation paper according to claim 3, characterized in that, The modified bismaleimide resin comprises bismaleimide, bisphenol A diallyl ether and triallyl isocyanurate and t-butyl peroxy benzoate in a mass ratio of 100:30-50:5-20:0.5-1.

5. The high thermal conductive filler composite insulation paper according to claim 3, characterized in that, The toughening agent comprises at least one of carboxyl-terminated butyl nitrile rubber, hydroxyl-terminated butyl nitrile rubber and epoxy-terminated butyl nitrile rubber.

6. The high thermal conductivity filler composite insulation paper of claim 1, wherein, The heat-conducting filler comprises aluminum oxide and boron nitride, wherein the aluminum oxide comprises 100μm aluminum oxide, 50μm aluminum oxide, 10μm aluminum oxide, 5μm aluminum oxide and 300nm spherical aluminum oxide in a mass ratio of 80-100:40-60:10-30:10-30:3-15, and the boron nitride comprises 5μm hexagonal boron nitride, 5μm cubic boron nitride and 10nm hexagonal boron nitride in a mass ratio of 10-30:10-30:3-15.

7. The high thermal conductivity filler composite insulation paper according to claim 1, wherein, The insulating paper is PET insulating paper or aramid insulating paper, the thickness of the insulating paper is 0.05mm~1.5mm, the width is 914mm~1280mm, and the gram weight is 20g / cm 2 ~900g / cm 2 .

8. A method for producing the high thermal conductive filler composite insulation paper according to any one of claims 1-7, characterized in that, The method comprises the following steps: The modified bismaleimide resin and the toughening agent are treated under stirring and heating to obtain an adhesive resin; The aluminum oxide and the boron nitride are co-dissolved and co-blended to prepare a heat-conducting filler; The adhesive resin is heated under stirring until the viscosity is reduced to 300-400mPa·s, and the heat-conducting filler is added for continuous stirring to obtain a heat-conducting resin; The heat-conducting resin is cooled and crushed to obtain a heat-conducting resin powder; The heat-conducting resin powder is scattered on the surface of the insulating paper at a preset rate, and after heat treatment and cooling, the heat-conducting resin paper is prepared.

9. The production method according to claim 8, characterized by, The heating temperature of the stirring and heating is 55-70℃, the holding time is 0.5-1h, and the stirring rate is 250-300rpm; During the cooling and crushing of the heat-conducting resin, the temperature after cooling is 25-27℃, and the particle size after crushing is 80-100mesh.

10. The preparation method according to claim 8, characterized in that, The heat treatment comprises three-stage drying treatment, specifically, the first-stage drying temperature is 60-90℃, the drying time is 0.5-5min, the second-stage drying temperature is 130-180℃, the drying time is 1-10min, and the third-stage drying temperature is 30-60℃, and the drying time is 0.5-3min.

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