An Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and its preparation method

Abstract

This invention discloses an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and its preparation method, belonging to the technical field of thermally conductive composite material synthesis methods. The method involves adding calcium sulfate whiskers to an aqueous solution of urea and aluminum sulfate octadecahydrate, and obtaining Al(OH)3 modified calcium sulfate whiskers through heating and stirring. These whiskers are then dispersed in a mixed solution of epoxy resin and a curing agent, and the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material is prepared by casting. The prepared thermally conductive composite material has a dense internal structure, significant thermal conductivity, and good insulation properties. It can effectively dissipate and conduct heat to maintain the normal operating temperature and performance of electronic components. When used in electronic products, it can effectively guide heat outwards, reducing the risk of overheating during electronic component operation.

Description

Technical Field

[0001] This invention belongs to the technical field of thermally conductive composite material synthesis methods, specifically relating to an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and its preparation method. Background Technology

[0002] Electronic devices typically generate continuous heat during operation, requiring heat dissipation through conduction or heat transfer. Using thermally conductive materials is one effective method to solve this problem. Generally, polymer materials have poor thermal conductivity, typically around 0.2 W / m². -1 K -1 To improve the thermal conductivity of polymer materials, a composite approach is often employed. For example, introducing fillers such as aluminum hydroxide, alumina, and boron nitride can create thermally conductive pathways within the resin matrix, thereby improving the thermal conductivity of the polymer material.

[0003] Generally speaking, thermally conductive fillers with large aspect ratios are more likely to interlock and form interconnected thermal conductive pathways within the resin matrix. However, commonly used thermally conductive fillers such as aluminum hydroxide, alumina, and boron nitride are all granular, which limits the development of thermally conductive composite materials. In addition, matrix fillers are generally expensive, leading to increased costs for composite materials and hindering their widespread application.

[0004] To address the existing technical problems of poor thermal conductivity and high preparation cost of epoxy resins, there is an urgent need for modification research to improve the thermal conductivity of epoxy resin composites, enabling them to meet the application requirements of high thermal conductivity applications, reduce the overall cost of composite materials, and enhance their market competitiveness. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and its preparation method, so as to solve the technical problems of poor thermal conductivity of epoxy resin and high preparation cost.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, comprising the following steps:

[0008] 1) Calcium sulfate whiskers were ultrasonically dispersed in deionized water, and then aluminum sulfate octadecahydrate was added and stirred until completely dissolved. Urea was then added and heated and stirred. After filtration, washing and drying, Al(OH)3 modified calcium sulfate whiskers were obtained.

[0009] 2) Add the Al(OH)3 modified calcium sulfate whiskers obtained in step 1) to butyl acetate / n-butanol solvent, disperse by ultrasonication, add epoxy resin, curing agent, leveling agent, dispersant, defoamer and anti-settling agent, stir, pour into mold, heat and cure to obtain Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite material.

[0010] Preferably, in step 1), the mass ratio of calcium sulfate whiskers: urea: aluminum sulfate octadecylhydrate: deionized water is 1: (0.9~2.7): (1.6~4.8): (25~75).

[0011] Preferably, in step 1), the heating and stirring temperature is 80~95℃ and the time is 3~5 h; the drying conditions are: drying at 80~95℃ for 8 h, then drying at 200~220℃ for 2 h.

[0012] Preferably, in step 1), the calcium sulfate whiskers are prepared from gypsum or industrial by-product gypsum, with an aspect ratio of 20 to 30.

[0013] Preferably, in step 2), the mass ratio of Al(OH)3 modified calcium sulfate whiskers: butyl acetate / n-butanol solvent is 1:(1~3):epoxy resin:curing agent:defoamer:dispersant:antisettling agent:leveling agent is 1:(1~3):(0.5~1.3):(0.1~1):(0.005~0.015):(0.01~0.015):(0.005~0.015):(0.005~0.015).

[0014] Preferably, in step 2), the butyl acetate / n-butanol solvent is prepared by mixing butyl acetate and n-butanol; the mass ratio of butyl acetate to n-butanol is 1:1.

[0015] Preferably, in step 2), the epoxy resin is at least one of E-51, E-44 and E-20; the curing agent is polyamide; the leveling agent is BYK-333; the dispersant is BYK-110; the defoamer is BYK-141; and the anti-settling agent is BYK-410.

[0016] Preferably, in step 2), the mass ratio of Al(OH)3 modified calcium sulfate whiskers to Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite material is (0.3~0.6):1.

[0017] Preferably, in step 2), the heating curing conditions are: 45℃ for 6 hours, 60℃ for 4 hours, 80℃ for 3 hours, 100℃ for 2 hours, and 120℃ for 1 hour.

[0018] This invention also discloses an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, prepared by the above-described method, with a maximum thermal conductivity of 1.16 W / m. -1 K -1 Compared to pure epoxy resin, its thermal conductivity is increased by 480%; its volume resistivity is 10 Ω·cm. 12 Ω m or more; surface resistivity is 10 12 Ω m or more.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention discloses a method for preparing Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite materials. First, using calcium sulfate whiskers as a raw material results in more stable product properties and structure. By introducing calcium sulfate whiskers into the epoxy resin matrix, the internal structure of the matrix is ​​optimized, leading to a denser microstructure in the obtained thermally conductive composite material. Second, by loading Al(OH)3 onto the surface of inorganic particles, the CSW (calcium sulfate-based composite) exhibits good thermal conductivity and insulation, improving thermal management in electronic packaging thermal interface materials. Third, the calcium sulfate whiskers, mainly distributed in a plate-like morphology within the matrix material, increase the thermal interface and thermal contact points within the matrix, constructing thermal conduction pathways and reducing interfacial thermal resistance. Fourth, the introduction of calcium sulfate whiskers significantly reduces the preparation cost of thermally conductive and insulating materials, meeting practical production needs.

[0021] This invention also discloses the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material prepared by the above method, which can achieve a maximum W / m² of 1.16 W / m². -1 K -1 Its high thermal conductivity, compared to pure PE (0.20 W / m²), -1 K -1 Its thermal conductivity is increased by 480%. Meanwhile, the composite material has 10... 12 With a volume / surface resistivity above Ω m, it exhibits excellent electrical insulation. This is because the material has a dense internal structure, significant thermal conductivity, good insulation, plasticity, and lightweight characteristics. Through the formation of thermally conductive fillers, it can effectively dissipate and conduct heat to maintain the normal operating temperature and performance of electronic components. Attached Figure Description

[0022] Figure 1The images show the microstructure and energy dispersive spectroscopy (EDS) spectra of Al(OH)3 modified calcium sulfate whiskers (Al(OH)3@CSW) disclosed in Example 1 of this invention; wherein, (a) is the EDS spectra of Al(OH)3@CSW; (b) is the SEM image of Al(OH)3@CSW; (c) is the distribution map of Ca; (d) is the distribution map of S; (e) is the distribution map of O; and (f) is the distribution map of Al.

[0023] Figure 2 This invention discloses the relationship between the thermal conductivity of Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and the filler content.

[0024] Figure 3 The diagram shows the relationship between the surface resistivity, volume resistivity, breakdown voltage, and electrical strength of the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material disclosed in this invention and the filler content; wherein, (a) is a graph showing the relationship between surface resistivity and volume resistivity and filler content; and (b) is a graph showing the relationship between breakdown voltage and electrical strength and filler content. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings:

[0028] Calcium sulfate whiskers (CSW) have attracted much attention due to their unique morphology, good compatibility, and economical price. Reports indicate that the introduction of CSW can significantly improve the mechanical properties of composite materials, and its commercial price is among the lowest of all inorganic fillers. Furthermore, due to the large aspect ratio and diverse morphologies of CSW, when dispersed in the composite matrix, the whiskers easily contact each other to form an interconnected network structure, thereby promoting improved thermal conductivity. Aluminum oxide (A₂O₃) is a material with excellent thermal conductivity and a high thermal coefficient. When A₂O₃ is loaded onto the surface of inorganic particles, the thermal conductivity of aluminum can be fully utilized to rapidly transfer heat. This is because inorganic particles typically have a large surface area, and A₂O₃ loading provides more heat transfer interfaces, enhancing the thermal conductivity. Secondly, inorganic particles generally have a high heat capacity; when they receive heat, their temperature rises, allowing them to store more heat and better absorb, transfer, and release heat under different environments. Therefore, it is considered to load aluminum oxide onto the surface of lamellar calcium sulfate whiskers to improve thermal conductivity by increasing the number of thermal contact points and interfaces. However, previous research on loading aluminum oxide onto lamellar whiskers is almost non-existent, and exploring a suitable approach is still needed, which presents a certain challenge.

[0029] This invention discloses a method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, comprising the following steps:

[0030] 1) Calcium sulfate whiskers were added to a beaker containing deionized water and ultrasonically dispersed. Then aluminum sulfate octadecahydrate was added and stirred until completely dissolved. Urea was added and the mixture was heated and stirred at 80-95℃ for 3-5 h. After filtration and washing, the mixture was dried at 80-95℃ for 8 h and then dried at 200-220℃ for 2 h to obtain Al(OH)3 modified calcium sulfate whiskers.

[0031] 2) Mix butyl acetate and n-butanol to prepare butyl acetate / n-butanol solvent; place the Al(OH)3 modified calcium sulfate whiskers obtained in step 1) into a glass bottle containing butyl acetate / n-butanol solvent to obtain a mixed solution; disperse the mixed solution by ultrasonication for 30 min, then add epoxy resin, curing agent, leveling agent, dispersant, defoamer and anti-settling agent to the bottle in proportion, stir in a stirrer for 5 h, pour into a mold, heat and cure to obtain Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite material.

[0032] In a preferred embodiment of the present invention, in step 1), calcium sulfate whiskers are prepared from gypsum or industrial by-product gypsum, with an aspect ratio of 20 to 30.

[0033] The mass ratio of calcium sulfate whiskers: urea: aluminum sulfate octadechydrate: deionized water is 1: (0.9~2.7): (1.6~4.8): (25~75).

[0034] In step 2), the mass ratio of Al(OH)3 modified calcium sulfate whiskers: butyl acetate / n-butanol solvent: epoxy resin: curing agent: defoamer: dispersant: anti-settling agent: leveling agent is 1: (1~3): (0.5~1.3): (0.1~1): (0.005~0.015): (0.01~0.015): (0.005~0.015): (0.005~0.015); the butyl acetate / n-butanol solvent is prepared by mixing butyl acetate and n-butanol, wherein the mass ratio of butyl acetate to n-butanol is 1:1.

[0035] The mass ratio of Al(OH)3 modified calcium sulfate whiskers to butyl acetate / n-butanol solvent is 1:(1~3).

[0036] In step 3), the epoxy resin is at least one of E-51, E-44 and E-20; the curing agent is polyamide; the leveling agent is BYK-333; the dispersant is BYK-110; the defoamer is BYK-141; and the anti-settling agent is BYK-410.

[0037] The mass ratio of Al(OH)3 modified calcium sulfate whiskers to Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite material is (0.3~0.6):1.

[0038] In step 2), the heating curing conditions are as follows: after heating on a heating table at 45℃ for 6 hours, the oven temperature is increased in stages: 60℃ for 4 hours, 80℃ for 3 hours, 100℃ for 2 hours, and 120℃ for 1 hour, to obtain Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite material.

[0039] This invention also discloses a thermally conductive composite material prepared by the above method, which can achieve a maximum thermal conductivity of 1.16 W / m². -1 K -1 Its high thermal conductivity, compared to pure PE (0.20 W / m²), -1 K -1 Its thermal conductivity is increased by 480%. Meanwhile, the composite material has 10... 12 With a volume resistivity and surface resistivity above Ωm, the material exhibits excellent electrical insulation. This is because its internal structure is dense, resulting in significant thermal conductivity. It also possesses good insulation, plasticity, and lightweight characteristics. Through the formation of thermally conductive fillers, it can effectively dissipate and conduct heat, thereby maintaining the normal operating temperature and performance of electronic components.

[0040] Example 1

[0041] A method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, characterized by comprising the following steps:

[0042] Step 1: Weigh 1 part of calcium sulfate whiskers with an aspect ratio of 20 and add them to 25 parts of deionized water. Sonicate for 30 min to obtain a suspension. Add 1.6 parts of aluminum sulfate octadecahydrate and stir until dissolved. Then add 0.9 parts of urea. After the addition is complete, continue heating and stirring at 80℃ for 5 h. Then filter while hot, wash with deionized water and centrifuge 5 times. Place the centrifuged product in an 80℃ oven to dry for 8 h, and then heat to 200℃ to dry for 2 h to obtain modified calcium sulfate whiskers for later use.

[0043] Step 2: Prepare a mixed solvent of butyl acetate and n-butanol in a 1:1 ratio. Weigh 1 part of Al(OH)3@CSW composite whiskers and 3 parts of the mixed solvent and place them in a glass bottle.

[0044] Step 3: After ultrasonically dispersing the solution in the glass bottle, add 1.3 parts of epoxy resin E-44, 1.0 part of polyamide curing agent, then add 0.01 parts of dispersant BYK-110, 0.005 parts of leveling agent BYK-333, 0.005 parts of defoamer BYK-141 and anti-settling agent BYK-410. Stir for 5 hours, then remove the solvent using a rotary evaporator without crosslinking reaction. Then heat on a heating platform at 45℃ for 6 hours, followed by stepwise heating in an oven (heating at 60℃ for 4 hours, 80℃ for 3 hours, 100℃ for 2 hours, and 120℃ for 1 hour) to obtain the composite material.

[0045] The thermally conductive composite material prepared by the above method exhibits an interconnected network of composite whiskers within the matrix, which effectively conducts heat. The thermal conductivity of the Al(OH)3@CSW-30 / EP composite material reaches 0.41 W / m. -1 K -1 Compared to pure EP (0.20 W m) -1 K -1 The thermal conductivity of this composite material is increased by 105%. Simultaneously, the volume or surface resistivity of this composite material is higher than 10⁻⁶. 12 The tensile strength reached 37.3 MPa, which is 38% higher than that of pure EP (27 MPa), and the breakdown strength was 16.6 KV / mm, which is 98% higher than that of pure EP (8.4 KV / mm).

[0046] See Figure 1The images show the microstructure and energy dispersive spectroscopy (EDS) spectra of Al(OH)3 modified calcium sulfate whiskers (Al(OH)3@CSW) disclosed in Example 1 of this invention. (a) is the EDS spectra of Al(OH)3@CSW; (b) is the SEM image of Al(OH)3@CSW; (c) shows the distribution of Ca; (d) shows the distribution of S; (e) shows the distribution of O; and (f) shows the distribution of Al. The images clearly show a dense layer of fine particles covering the originally smooth surface of CSW. Combining the EDS analysis and mapping elemental distribution results, it can be seen that the distribution of Al and O elements is completely consistent with the distribution profile of Ca, confirming that these fine particles are Al(OH)3. Morphological analysis shows that Al(OH)3 can be successfully loaded onto the surface of CSW, indicating that the Al(OH)3@CSW composite whiskers have been successfully prepared. The prepared insulating and thermally conductive composite material can achieve a maximum W / m² of 1.16 W / m². -1 K -1 Its high thermal conductivity, compared to pure EP (0.20 W / m²), -1 K -1 Its thermal conductivity is increased by 480%. Meanwhile, the composite material has 10... 12 With a volume or surface resistivity above Ω cm, it possesses excellent electrical insulation properties. It can effectively conduct heat to maintain the normal operating temperature and performance of electronic components.

[0047] Example 2

[0048] A method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, characterized by comprising the following steps:

[0049] Step 1: Weigh 1 part of calcium sulfate whiskers with an aspect ratio of 25 and add them to 75 parts of deionized water. Sonicate for 30 min to obtain a suspension. Add 4.8 parts of aluminum sulfate octadecahydrate and stir until dissolved. Then add 2.7 parts of urea. After the addition is complete, continue heating and stirring at 95℃ for 3 h. Then filter while hot, wash with deionized water and centrifuge 5 times. Place the centrifuged product in a 90℃ oven to dry for 8 h, then heat to 210℃ and dry for 2 h to obtain modified calcium sulfate whiskers for later use.

[0050] Step 2: Prepare a mixed solvent of butyl acetate and n-butanol in a 1:1 ratio. Weigh 1 part of Al(OH)3@CSW composite whiskers and 2 parts of the mixed solvent and place them in a glass bottle.

[0051] Step 3: After ultrasonically dispersing the solution in the glass bottle, add 0.8 parts of epoxy resin E-44, 0.7 parts of polyamide curing agent, then add 0.01 parts of dispersant BYK-110, 0.005 parts of leveling agent BYK-333, and 0.005 parts of defoamer BYK-141 and anti-settling agent BYK-410. Stir for 5 hours, then remove the solvent using a rotary evaporator without crosslinking reaction. Then place on a heating platform and heat at 45°C for 6 hours, followed by stepwise heating in an oven (heating at 60°C for 4 hours, 80°C for 3 hours, 100°C for 2 hours, and 120°C for 1 hour) to obtain the composite material.

[0052] The thermally conductive composite material prepared by the above method exhibits significant application performance and characteristics. The thermal conductivity of the Al(OH)3@CSW-40 / EP composite material reaches 0.52 W / m. -1 K -1 Compared to pure EP (0.20 W m) -1 K -1 The thermal conductivity of this composite material is increased by 160%. Simultaneously, the volume or surface resistivity of this composite material is higher than 10⁻⁶. 12 The tensile strength reached 40.2 MPa, which is 49% higher than that of pure EP (27 MPa), and the breakdown strength was 16.2 KV / mm, which is 97% higher than that of pure EP (8.4 KV / mm).

[0053] Example 3

[0054] A method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, characterized by comprising the following steps:

[0055] Step 1: Weigh 1 part of calcium sulfate whiskers with an aspect ratio of 30 and add them to 50 parts of deionized water. Sonicate for 30 min to obtain a suspension. Add 3.2 parts of aluminum sulfate octadecahydrate and stir until dissolved. Then add 1.8 parts of urea. After the addition is complete, continue heating and stirring at 90℃ for 4 h. Then filter while hot, wash with deionized water and centrifuge 5 times. Place the centrifuged product in an 85℃ oven to dry for 8 h, then heat to 215℃ and dry for 2 h to obtain modified calcium sulfate whiskers for later use.

[0056] Step 2: Prepare a mixed solvent of butyl acetate and n-butanol in a 1:1 ratio. Weigh 1 part of Al(OH)3@CSW composite whiskers and 1 part of the mixed solvent and place them in a glass bottle.

[0057] Step 3: After ultrasonically dispersing the solution in the glass bottle, add 0.5 parts of epoxy resin E-51, 0.5 parts of polyamide curing agent, then add 0.012 parts of dispersant BYK-110, 0.01 parts of leveling agent BYK-333, and 0.01 parts of defoamer BYK-141 and anti-settling agent BYK-410. Stir for 1 hour, then remove the solvent using a rotary evaporator without crosslinking reaction. Then heat on a heating platform at 45°C for 6 hours, followed by stepwise heating in an oven (heating at 60°C for 4 hours, 80°C for 3 hours, 100°C for 2 hours, and 120°C for 1 hour) to obtain the composite material.

[0058] The thermally conductive composite material prepared by the above method exhibits significant application performance and characteristics. The interconnected network formed by the composite whiskers within the matrix effectively conducts heat. The thermal conductivity of the Al(OH)3@CSW-50 / EP composite material reaches 0.63 W / m. -1 K -1 Compared to pure EP (0.20 W m) -1 K -1 The thermal conductivity of this composite material is increased by 215%. Simultaneously, the volume or surface resistivity of this composite material is higher than 10⁻⁶. 12 The tensile strength reached 38.1 MPa, which is 41% higher than that of pure EP (27 MPa), and the breakdown strength was 11.2 KV / mm, which is 32% higher than that of pure EP (8.4 KV / mm).

[0059] Example 4

[0060] A method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, characterized by comprising the following steps:

[0061] Step 1: Weigh 1 part of calcium sulfate whiskers with an aspect ratio of 30 and add it to 25 parts of deionized water. Sonicate for 30 min to obtain a suspension. Add 3.2 parts of aluminum sulfate octadecahydrate and stir until dissolved. Then add 2.7 parts of urea. After the addition is complete, continue heating and stirring at 85℃ for 4.5 h. Then filter while hot, wash with deionized water and centrifuge 5 times. Place the centrifuged product in a 95℃ oven to dry for 8 h, then heat to 200℃ and dry for 2 h to obtain modified calcium sulfate whiskers for later use.

[0062] Step 2: Prepare a mixed solvent of butyl acetate and n-butanol in a 1:1 ratio. Weigh 1 part of Al(OH)3@CSW composite whiskers and 1 part of the mixed solvent and place them in a glass bottle.

[0063] Step 3: After ultrasonically dispersing the solution in the glass bottle, add 0.56 parts of epoxy resin E-20, 0.1 parts of polyamide curing agent, then add 0.015 parts of dispersant BYK-110 and leveling agent BYK-333, and 0.015 parts of defoamer BYK-141 and anti-settling agent BYK-410. Stir for 5 hours, remove the solvent using a rotary evaporator without crosslinking reaction, then heat on a heating platform at 45℃ for 6 hours, followed by stepwise heating in an oven (heating at 60℃ for 4 hours, 80℃ for 3 hours, 100℃ for 2 hours, and 120℃ for 1 hour) to obtain the composite material.

[0064] The thermally conductive composite material prepared by the above method exhibits significant application performance and characteristics. The interconnected network formed by the composite whiskers within the matrix effectively conducts heat. The thermal conductivity of the Al(OH)3@CSW-60 / EP composite material reaches 1.16 W / m. -1 K -1 Compared to pure EP (0.20 W m) -1 K -1 Its thermal conductivity is increased by 480%. Simultaneously, the volume or surface resistivity of this composite material is higher than 10⁻⁶. 12 The tensile strength reached 32.1 MPa, which is 19% higher than that of pure EP (27 MPa), and the breakdown strength was 8.6 KV / mm, which is 2% higher than that of pure EP (8.4 KV / mm).

[0065] Example 5

[0066] A method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, characterized by comprising the following steps:

[0067] Step 1: Weigh 1 part of calcium sulfate whiskers with an aspect ratio of 25 and add them to 60 parts of deionized water. Sonicate for 30 min to obtain a suspension. Add 4.0 parts of aluminum sulfate octadechydrate and stir until dissolved. Then add 2.4 parts of urea. After the addition is complete, continue to heat and stir at 92℃ for 3.5 h. Then filter while hot, wash with deionized water and centrifuge 5 times. Place the centrifuged product in a 90℃ oven to dry for 8 h, then heat to 220℃ and dry for 2 h to obtain modified calcium sulfate whiskers for later use.

[0068] Step 2: Prepare a mixed solvent of butyl acetate and n-butanol in a 1:1 ratio. Weigh 1 part of Al(OH)3@CSW composite whiskers and 2 parts of the mixed solvent and place them in a glass bottle.

[0069] Step 3: After ultrasonically dispersing the solution in the glass bottle, add 0.8 parts of epoxy resin E-44, 0.7 parts of polyamide curing agent, followed by 0.012 parts of dispersant BYK-110, 0.008 parts of leveling agent BYK-333, and 0.008 parts of defoamer BYK-141 and anti-settling agent BYK-410. Stir for 5 hours, remove the solvent using a rotary evaporator without crosslinking reaction, then heat at 45°C for 6 hours on a heating platform, followed by stepped heating in an oven (60°C for 4 hours, 80°C for 3 hours, 100°C for 2 hours, and 120°C for 1 hour) to obtain the composite material.

[0070] The thermally conductive composite material prepared by the above method exhibits significant application performance and characteristics. The thermal conductivity of the Al(OH)3@CSW-40 / EP composite material reaches 0.51 W / m. -1 K -1 .

[0071] Comparison Example

[0072] A method for preparing an epoxy resin thermally conductive composite material, characterized by comprising the following steps:

[0073] Step 1: Prepare a mixed solvent of butyl acetate and n-butanol in a 1:1 ratio.

[0074] Step 2: Add 5 parts epoxy resin E-44, 4 parts polyamide curing agent and 3 parts mixed solvent to the glass bottle. Remove the solvent using a rotary evaporator without causing a cross-linking reaction. Then place the bottle on a heating table and heat at 45°C for 6 hours. After that, heat the bottle in an oven in a stepped manner (heating at 60°C for 4 hours, 80°C for 3 hours, 100°C for 2 hours, and 120°C for 1 hour) to obtain the composite material.

[0075] An epoxy resin material prepared according to the above method exhibits excellent electrical insulation properties as a significant performance characteristic. The prepared insulating material achieves a strength of 0.20 W / m². -1 K -1 The thermal conductivity has a value of 10. 14 With a volume or surface resistivity above Ω cm, it exhibits excellent electrical insulation properties. Furthermore, the material has a tensile strength of 27 MPa and a breakdown strength of 8.4 KV / mm.

[0076] Figure 2This figure shows the relationship between the thermal conductivity of the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and the filler content in Example 1 of this invention. As can be seen from the figure, the thermal conductivity of the composite material gradually improves with the increase of the amount of modified whiskers added. When the amount of Al(OH)3 modified calcium sulfate whiskers added is 60%, the thermal conductivity of the composite material can reach 1.16 W / m². -1 K -1 .

[0077] Figure 3 This invention discloses the relationship between the surface resistivity, volume resistivity, breakdown voltage, and electrical strength of the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and the filler content in Example 1. (a) shows the relationship between breakdown voltage and electrical strength and filler content; (b) shows the relationship between surface resistivity and volume resistivity and filler content. As can be seen from the figures, the addition of modified whiskers can effectively improve the pressure resistance of the composite material, and the surface resistivity and volume resistivity of the composite material do not decrease significantly after the addition of whiskers, remaining at around 10. 14 With a strength of Ω cm or higher, it exhibits excellent insulation performance.

[0078] This invention discloses an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material and its preparation method. Calcium sulfate whiskers are added to an aqueous solution of urea and aluminum sulfate octadecylhydrate, and Al(OH)3 modified calcium sulfate whiskers are obtained by heating and stirring. These whiskers are then dispersed in a mixed solution of epoxy resin and a curing agent, and the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material is prepared by casting. The prepared thermally conductive composite material has a dense internal structure, significant thermal conductivity, good insulation, plasticity, and lightweight characteristics. It can effectively dissipate and conduct heat to maintain the normal operating temperature and performance of electronic components. This Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material has good heat dissipation and insulation properties when used in integrated circuits of electronic components. When used in electronic products, it can effectively guide heat outwards and reduce the risk of overheating during operation of electronic components.

[0079] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing an Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, characterized in that, Includes the following steps: 1) Calcium sulfate whiskers were ultrasonically dispersed in deionized water, and then aluminum sulfate octadecahydrate was added and stirred until completely dissolved. Urea was then added and heated and stirred. After filtration, washing and drying, Al(OH)3 modified calcium sulfate whiskers were obtained. 2) The Al(OH)3 modified calcium sulfate whiskers obtained in step 1) are added to butyl acetate / n-butanol solvent, ultrasonically dispersed, and then epoxy resin, curing agent, leveling agent, dispersant, defoamer and anti-settling agent are added. After stirring, the solvent is removed by rotary evaporator under the condition that no cross-linking reaction occurs. The mixture is then poured into a mold and heated to cure, to obtain Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite material. In step 1), the mass ratio of calcium sulfate whiskers: urea: aluminum sulfate octadechydrate: deionized water is 1: (0.9~2.7): (1.6~4.8): (25~75). The heating and stirring temperature is 80~95℃, and the time is 3~5 h; the drying conditions are: drying at 80~95℃ for 8 h, then transferring to 200~220℃ for 2 h. In step 2), the mass ratio of Al(OH)3 modified calcium sulfate whiskers: butyl acetate / n-butanol solvent: epoxy resin: curing agent: defoamer: dispersant: anti-settling agent: leveling agent is 1: (1~3): (0.5~1.3): (0.1~1): (0.005~0.015): (0.01~0.015): (0.005~0.015): (0.005~0.015).

2. The preparation method of the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 1), the calcium sulfate whiskers are prepared from gypsum and have an aspect ratio of 20 to 30.

3. The method for preparing the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 2), the butyl acetate / n-butanol solvent is prepared by mixing butyl acetate and n-butanol; the mass ratio of butyl acetate to n-butanol is 1:

1.

4. The preparation method of the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 2), the epoxy resin is at least one of E-51, E-44 and E-20; the curing agent is polyamide; the leveling agent is BYK-333; the dispersant is BYK-110; the defoamer is BYK-141; and the anti-settling agent is BYK-410.

5. The method for preparing the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 2), the mass ratio of Al(OH)3 modified calcium sulfate whiskers to Al(OH)3 modified calcium sulfate whiskers / epoxy resin thermally conductive composite material is (0.3~0.6):

1.

6. The method for preparing the Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 2), the heating and curing conditions are: 45℃ for 6 hours, 60℃ for 4 hours, 80℃ for 3 hours, 100℃ for 2 hours, and 120℃ for 1 hour.

7. An Al(OH)3 modified calcium sulfate whisker / epoxy resin thermally conductive composite material, characterized in that, The thermally conductive composite material, prepared by any one of claims 1 to 6, has a maximum thermal conductivity of 1.16 W·m. -1 ·K -1 Compared to pure epoxy resin, its thermal conductivity is increased by 480%; its volume resistivity is 10 Ω·cm. 12 Ω m or more.

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