Preparation method of high-toughness high-thermal-conductivity thermal interface composite material

Abstract

The application discloses a preparation method of high-toughness and high-thermal-conductivity thermal interface composite material. The thermal interface composite material prepared by the application is composed of a base resin and metal thermal conductive fillers, the base resin comprises silicone resin, a curing agent, a catalyst and a functional additive, and the thermal conductive fillers are metal nanoparticles with fractal growth. The silicone resin, the curing agent and the catalyst are mixed and stirred to obtain a resin precursor, then the spherical or urchin-shaped metal nanoparticle thermal conductive fillers are added and stirred, and then the thermal interface composite material is obtained by coating the mixture into a thin film, curing at a certain temperature, and obtaining the high-toughness and high-thermal-conductivity thermal interface composite material. The metal thermal conductive fillers with fractal growth morphology in the urchin shape are adopted, based on the high specific surface area and physical embedding effect of the urchin-shaped fillers, the thermal interface composite material is easy to prepare, has a thermal conductivity of up to 8.0 W / mK and excellent mechanical flexibility, and has the characteristics of low energy consumption, simple process and safety and environmental protection.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of heat-conducting composite materials, and particularly relates to a preparation method of a high-toughness high-thermal-conductivity thermal interface composite material. BACKGROUND

[0002] With the rapid development of electronic information technology such as wireless base stations and 5G communication equipment, electronic devices are increasingly high-powered and integrated, causing a sharp rise in heat density in the system, which seriously threatens the stability of the devices. Heat-conducting polymer composites have many advantages such as good thermal conductivity, high specific strength, easy molding and processing, and have become key materials in the field of interface thermal conduction.

[0003] Polymers have poor intrinsic thermal conductivity, and the introduction of high-thermal-conductivity fillers to construct a continuous thermal conduction path is the most effective method to improve the thermal conductivity. By template method, freeze-drying method, mechanical stretching method and magnetic field induction, the thermal conductive fillers are closely arranged to construct an anisotropic continuous thermal conduction path, which can significantly improve the thermal conductivity, but the preparation process is complex and the conditions are harsh, which is difficult to meet the actual application requirements.

[0004] On the other hand, one-dimensional linear and tubular thermal conductive fillers exhibit high thermal conductivity in the continuous thermal conduction network in the composite system, but the one-dimensional fillers with high aspect ratio are prone to entanglement, which causes the viscosity of the prepolymer liquid to increase sharply, resulting in a decrease in interfacial wettability and a sharp increase in interfacial thermal resistance; zero-dimensional spherical filler thermal conductive composites have the advantages of low prepolymer liquid viscosity, small interfacial thermal resistance, simple preparation and convenient operation, but the effective contact area of the spherical structure is small, and it is difficult to form a continuous thermal conduction path, so it is difficult to further improve the thermal conductivity. Therefore, the preparation of thermal interface composites with high thermal conductivity and high mechanical flexibility has always been a research difficulty in the field of thermal interface composites. SUMMARY

[0005] In order to solve the problems of insufficient thermal conductivity and mechanical flexibility of the existing thermal conductive composites, the present application uses metal thermal conductive fillers with urchin-like fractal growth, and uses the physical embedding of the urchin-like morphology of the thermal conductive fillers to not only improve the thermal conductivity of the composite material, but also improve the mechanical flexibility of the composite material.

[0006] One of the purposes of the present application is to provide a high-toughness high-thermal-conductivity thermal interface composite material, which has high thermal conductivity, high toughness and high tensile strength.

[0007] Another purpose of the present application is to provide a preparation method of the high-toughness high-thermal-conductivity thermal interface composite material.

[0008] In order to achieve the above object, the technical scheme adopted by the present application is: a high-toughness and high-thermal-conductivity thermal interface composite material, which comprises a base resin and a metal thermal conductive filler; further, the thermal conductive coefficient of the thermal interface composite material is greater than 8.0 W / mK, and high mechanical flexibility is maintained in a wide temperature range.

[0009] Further, the base resin comprises an organic silicon resin, a curing agent, a catalyst and a functional additive, and the thermal conductive filler is a fractally grown metal nanoparticle.

[0010] Further, the organic silicon resin comprises one or a combination of at least two of a linear vinyl silicon resin, a branched vinyl silicon resin, a modified silicon resin or a silicon gel.

[0011] Further, the curing agent is one or a combination of at least two of a hydroxyl silicone oil, a vinyl silicone oil, a hydrogen-containing silicone oil or a phenyl silicone oil.

[0012] Further, the catalyst is at least one of chloroplatinic acid and isopropanol or diethenyltetramethylsiloxane or diethyl phthalate complex.

[0013] Further, the functional additive is one or a combination of at least two of a thickening agent, an anti-aging agent, an anti-etching agent and a flame retardant.

[0014] Further, the metal thermal conductive filler is at least one of gold, silver, copper, aluminum, iron, zinc and nickel nanoparticles.

[0015] Further, the fractally grown morphology of the metal thermal conductive filler is spherical and urchin-shaped.

[0016] Further, the mass ratio of the organic silicon resin to the thermal conductive filler is 5-20:1, the mass fraction of the curing agent in the base resin is 1%-5%, the mass fraction of the catalyst in the base resin is 0.05%-2%, and the mass fraction of the functional additive in the base resin is 0.1%-5%.

[0017] A preparation method of a high-toughness and high-thermal-conductivity thermal interface composite material, the specific steps are:

[0018] (1) Preparation of fractally grown metal thermal conductive filler

[0019] 1) Preparation of electrolyte: metal nitrate as electrodeposited metal salt, ionic liquid with structures (I-I) and (I-II) as additives, and dimethyl sulfoxide as solvent;

[0020]

[0021] Further, the synthesis of the ionic liquid additives of the structure of formula (I-I) and (I-II) is as follows:

[0022] The acetonitrile solution A of chloromethyl ether is added dropwise into the acetonitrile solution B of the intermediate product of formula II or III, and after reaction at 60-90℃ for 12-24h, the product is obtained by post-treatment; the ratio between the intermediate product of formula II or III and the amount of substance of chloromethyl ether is 1:1.0-5.0;

[0023]

[0024] Further, in the synthesis step of the ionic liquid additives of the structure of formula (I-I) and (I-II), the volume of acetonitrile in solution A is 10-20mL / g based on the mass of the intermediate product of formula II or III;

[0025] Further, in the synthesis step of the ionic liquid additives of the structure of formula (I-I) and (I-II), the volume of acetonitrile in solution B is 1-5mL / g based on the mass of chloromethyl ether;

[0026] Further, in the synthesis step of the ionic liquid additives of the structure of formula (I-I) and (I-II), the post-treatment method is as follows: the solvent acetonitrile in the reaction solution is evaporated under reduced pressure, the remaining mixture is washed with ether three times, and the solvent is evaporated under reduced pressure to obtain the ionic liquid additives of the structure of formula (I-I) or (I-II).

[0027] 2) Electrodeposition: ITO conductive glass is used as the cathode and anode respectively, and the electrolyte containing the ionic liquid additives of the structure of formula (I-I) and (I-II) prepared in step 1) is electrodeposited in an electrolytic cell to obtain spherical and urchin-shaped metal nanoparticles respectively, which are washed and dispersed in tetrahydrofuran solution for use.

[0028] Further, in the electrodeposition step, the length of the ITO conductive glass is 5-50cm, the width is 3-20cm, the thickness is 0.5-5mm, and the square resistance is 1-100Ω / cm 2 .

[0029] Further, the distance between the cathode and the anode is 0.02-1.0cm.

[0030] Further, the concentration of the ionic liquid additive in the electrolyte is 10-200mg / mL, the concentration of the metal nitrate is 50-150mg / mL, and the total amount of the electrolyte is 50-300mL.

[0031] Further, the electrodeposition voltage is 5-20V, and the current density is 10-100mA / cm 2 .

[0032] The electrolyte containing the ionic liquid additive with the structure shown in formula (I-I) or (I-II) can be prepared by electrodeposition, and the nanometer metal particle heat-conducting filler with spherical or sea urchin-shaped fractal growth shape is prepared.

[0033] (2) Preparation of high-toughness and high-thermal-conductivity thermal interface composite material

[0034] The silicone resin, the curing agent and the catalyst are mixed and stirred for 10-60 minutes to obtain a resin precursor, then the spherical or sea urchin-shaped metal nanoparticle heat-conducting filler is added and stirred for 10-60 minutes, and then the obtained mixture is coated into a thin film with a thickness of 1-15 mm, and cured at 50-140 DEG C for 5-60 minutes, so that the high-toughness and high-thermal-conductivity thermal interface composite material is obtained.

[0035] Further, the stirring speed is 100-800rmp.

[0036] The thermal conductivity of the thermal interface composite material prepared by the method is greater than 8.0W / mK, and the mechanical flexibility is high in a wide temperature range.

[0037] Compared with the prior art, the present application has the following advantages:

[0038] The metal heat-conducting filler with sea urchin-shaped fractal growth morphology is used in the present application, and based on the high specific surface area and physical embedding effect of the sea urchin-shaped filler, the thermal interface composite material is easy to prepare, has a thermal conductivity of up to 8.0W / mK and excellent mechanical flexibility, and has the characteristics of low energy consumption, simple process and safety and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 : The structure schematic diagram of the electrodeposition device in Example 3 of the present application;

[0040] Figure 2 : The morphology of the electrodeposited silver metal particles in Example 4 of the present application;

[0041] Figure 3 : The morphology of the electrodeposited silver metal particles in Example 5 of the present application; DETAILED DESCRIPTION

[0042] The technical solutions of the present application are further described below with specific examples. It should be understood that the specific examples described herein are only used to explain the present application, and the protection scope of the present application is not limited thereto.

[0043] The present application utilizes the basic principle of physical embedding of sea urchin-shaped metal heat-conducting fillers, increases the contact area between fillers, effectively reduces the load amount of fillers, realizes the heat-conducting enhancement and mechanical toughening performance of the thermal interface composite material. The thermal conductivity coefficient of the thermal interface composite material of the present application is greater than 8.0 W / mK, and the mechanical flexibility is maintained at a high level in a wide temperature range. The high-tough high-thermal-conductivity thermal interface composite material prepared by the method of the present application has good processing fluidity, is convenient for production operation control, and has broad industrialization and market prospects.

[0044] Example 1 Synthesis of 1,1-dimethylether morpholine chloride salt

[0045] Morpholine (20.0 mmol) and KOH (20.0 mmol) were stirred in CH3CN (20.0 mL) at 25℃ for 3 h, then 1-chloromethyl ether (20.0 mmol) was added to the mixture, and the reaction was continued under reflux conditions for 48 h. The volatile solvent CH3CN in the reaction mixture was removed by rotary evaporation, CH2Cl2 was added to the residue, extracted with water three times, and the organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was removed by rotary evaporation, then washed thoroughly with ether three times, and the obtained solid product was dried in a dynamic vacuum oven at 45℃ for 24 h to obtain the intermediate product represented by formula (II). The intermediate product represented by formula (II) (20.0 mmol) and 1-chloromethyl ether (20.0 mmol) were reacted in CH3CN (20.0 mL) under reflux conditions at 25℃ for 48 h. The volatile solvent CH3CN in the reaction mixture was removed by rotary evaporation, then washed thoroughly with ether three times, and the obtained solid product was dried in a dynamic vacuum oven at 45℃ for 24 h to obtain the solid product represented by formula (I-I), with a yield of 76.9%.

[0046]

[0047] Example 2 Synthesis of 1,1-dimethylether pyrrole chloride salt

[0048] Pyrrolidine (20.0 mmol) and KOH (20.0 mmol) were stirred in CH3CN (20.0 mL) at 25 °C for 3 h, then 1-chloromethyl ethyl ether (20.0 mmol) was added to the mixture, and the reaction was continued under reflux conditions for 48 h. The volatile solvent CH3CN was removed from the reaction mixture using the rotary evaporation method, and CH2Cl2was added to the residue, which was extracted with water three times and dried over anhydrous Na2SO4. The collected organic phase filtrate was removed by solvent using the rotary evaporation method, then washed thoroughly with ethyl ether three times, and the resulting solid product was removed by removing the ethyl ether, and finally dried in a dynamic vacuum oven at 45 °C for 24 h to obtain the intermediate product shown in formula (III). The intermediate product shown in formula (III) (20.0 mmol) and 1-chloromethyl ethyl ether (20.0 mmol) were reacted in CH3CN (20.0 mL) under reflux conditions for 48 h at 25 °C. The volatile solvent CH3CN was removed from the reaction mixture using the rotary evaporation method, then washed thoroughly with ethyl ether three times, and the resulting solid product was removed by removing the ethyl ether, and finally dried in a dynamic vacuum oven at 45 °C for 24 h to obtain the solid product shown in formula (I-II) with a yield of 73.1%.

[0049]

[0050] Example 3

[0051] As Figure 1 The electrodeposition device for precisely regulating the morphology of electrodeposited nanometal particles provided by the present embodiment is shown in the figure, which comprises two conductive electrodes 1 and 2 arranged in parallel and corresponding in the electrolytic cell 3, and an electrolyte 4 formed between the two conductive electrodes. The specific manufacturing process is as follows: the electrolyte 4 containing an ionic liquid additive, a metal salt and a solvent is placed in the electrolytic cell, and the conductive surfaces of the two conductive electrodes (indium tin oxide glass) 1 and 2 are arranged in parallel as an anode and a cathode, respectively.

[0052] Example 4

[0053] (1) Preparation of spherical metal heat-conducting filler

[0054] The ionic liquid additive shown in formula (I-I) 10-50 parts was dissolved in a solution of 2-10 parts of copper nitrate in 20-50 parts of dimethyl sulfoxide, and the mixture was stirred thoroughly. The electrodeposition electrolyte formed above was placed in the electrolytic cell, two pieces of conductive electrode with a thickness of 1 mm were taken, the distance was set to 0.5 cm, and a bias voltage of 5 V was loaded, and spherical copper metal nanoparticles were obtained at the cathode.

[0055] (2) Preparation of spherical metal heat-conducting filler-thermal interface composite material

[0056] The silicone resin, curing agent and catalyst are mixed in a mass ratio of 98:1:1, stirred at 500 rpm for 30 minutes to obtain a resin precursor. Then the prepared spherical metal nanoparticle thermal conductive filler is added, wherein the mass ratio of the thermal conductive filler to the silicone resin is 1:5, stirred at 500 rpm for 30 minutes, and then coated into a 5.0 mm thick film, cured at 100°C for 20 minutes, to obtain the spherical metal thermal conductive filler filled thermal interface composite material, as shown in Figure 2 .

[0057] Example 5

[0058] (1) Preparation of fractal growth urchin-shaped metal thermal conductive filler

[0059] The ionic liquid additive shown in formula (I-II) is added in 10-50 parts to a solution of 2-10 parts of copper nitrate in 20-50 parts of dimethyl sulfoxide, and stirred thoroughly. The formed electrodeposition electrolyte is placed in an electrolytic cell, two conductive electrodes with a thickness of 1 mm are taken, the distance is set to 0.5 cm, a bias voltage of 5V is loaded, and the fractal growth morphology of the metal copper obtained at the cathode is urchin-shaped metal thermal conductive filler nanoparticles.

[0060] (2) Preparation of urchin-shaped metal thermal conductive filler-thermal interface composite material

[0061] The silicone resin, curing agent and catalyst are mixed in a mass ratio of 98:1:1, stirred at 500 rpm for 30 minutes to obtain a resin precursor. Then the prepared spherical metal nanoparticle thermal conductive filler is added, wherein the mass ratio of the thermal conductive filler to the silicone resin is 1:5, stirred at 500 rpm for 30 minutes, and then coated into a 5.0 mm thick film, cured at 100°C for 20 minutes, to obtain the spherical metal thermal conductive filler filled thermal interface composite material, as shown in Figure 3 .

[0062] Example 6

[0063] The preparation method of the high-toughness high-thermal-conductivity thermal interface composite material is basically the same as that in Example 5, except that in step (2), the mass ratio of the thermal conductive filler to the silicone resin is 1:10.

[0064] Example 7

[0065] The preparation method of the high-toughness high-thermal-conductivity thermal interface composite material is basically the same as that in Example 5, except that in step (2), the mass ratio of the thermal conductive filler to the silicone resin is 1:15.

[0066] Example 8

[0067] The preparation method of the high-toughness and high-thermal-conductivity thermal interface composite material is basically the same as that in Example 5, except that in step (2), the mass ratio of the thermal conductive filler to the silicone resin is 1:20.

[0068] Table 1

[0069]

[0070] As shown in Table 1 are the thermal conductivity and mechanical properties of the thermal interface composite materials in Examples 4-8 of the present application. The electrochemical workstation used in the electrodeposition of the present application is Metrohm electrochemical workstation Autolab, the thermal conductivity of the prepared thermal interface composite material is tested by Hotdisk thermal flat plate method, and the mechanical properties of the thermal interface composite material are tested by 3400 series universal tensile machine.

[0071] The above examples are only for illustrating the technical concept and characteristics of the present application, the purpose is to enable the person skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A high toughness, high thermal conductivity thermal interface material, characterized in that, The thermal interface composite material is composed of a base resin and a metal heat-conducting filler, the base resin comprises silicone resin, curing agent, catalyst and functional additives, the heat-conducting filler is fractally grown metal nanoparticles, and the thermal conductivity of the thermal interface composite material is greater than 8.0 W / mK; The fractally grown metal nanoparticles have a morphology of sea urchin shape; The mass ratio of the silicone resin to the heat-conducting filler is 5-20:1; The preparation method of the thermal interface composite material comprises the following steps: Step 1, preparation of fractally grown metal heat-conducting filler; 1-1. Preparation of electrolyte: metal nitrate as electrodeposition metal salt, ionic liquid with structure (I-II) as additive, and dimethyl sulfoxide as solvent; 1-2. Electrodeposition: ITO conductive glass is used as cathode and anode respectively, and the electrolyte prepared in step 1-1 containing ionic liquid with structure (I-II) as additive is electrodeposited in an electrolytic cell to obtain sea urchin-shaped metal nanoparticles, which are washed and dispersed in tetrahydrofuran solution for standby; Step 2, preparation of high-toughness and high-thermal-conductivity thermal interface composite material; The silicone resin, curing agent and catalyst are mixed and stirred for 10-60 minutes to obtain a resin precursor, then the sea urchin-shaped metal nanoparticle heat-conducting filler is added and stirred for 10-60 minutes, and then a 1-15 mm thick film is obtained, which is cured at 50-140℃ for 5-60 minutes to obtain the high-toughness and high-thermal-conductivity thermal interface composite material.

2. The high toughness, high thermal conductivity thermal interface composite of claim 1, wherein, The silicone resin is at least one of linear vinyl silicone resin, branched vinyl silicone resin, modified silicone resin or silicone gel; The curing agent is a combination of one or more of hydroxyl silicone oil, vinyl silicone oil, hydrogen-containing silicone oil or phenyl silicone oil, and the mass fraction of the curing agent in the base resin is 1%-5%; The catalyst is at least one of chloroplatinic acid and isopropyl alcohol or divinyltetramethylsiloxane or diethyl phthalate complex, and the mass fraction of the catalyst in the base resin is 0.05%-2%; The functional additive is a combination of one or more of thickening agent, anti-aging agent, corrosion inhibitor and flame retardant, and the mass fraction of the functional additive in the base resin is 0.1%-5%.

3. The high toughness, high thermal conductivity thermal interface composite of claim 1, wherein, The metal is at least one of gold, silver, copper, aluminum, iron, zinc and nickel.

4. The method for preparing the high-toughness, high-thermal-conductivity thermal interface composite material as described in claim 1, characterized in that, The method comprises the following steps: Step 1, preparation of fractally grown metal heat-conducting filler; 1-1. Preparation of electrolyte: metal nitrate as electrodeposition metal salt, ionic liquid with structure (I-II) as additive, and dimethyl sulfoxide as solvent; 1-2. Electrodeposition: ITO conductive glass is used as cathode and anode respectively, and the electrolyte prepared in step 1-1 containing ionic liquid with structure (I-II) as additive is electrodeposited in an electrolytic cell to obtain sea urchin-shaped metal nanoparticles, which are washed and dispersed in tetrahydrofuran solution for standby; Step 2, preparation of high-toughness and high-thermal-conductivity thermal interface composite material; The silicone resin, curing agent and catalyst are mixed and stirred for 10-60 minutes to obtain a resin precursor, then the sea urchin-shaped metal nanoparticle thermal conductive filler is added and stirred for 10-60 minutes, then it is coated into a 1-15 mm thick film, and cured at 50-140℃ for 5-60 minutes to obtain the high-toughness high-thermal-conductivity thermal interface composite material.

5. The preparation method of the high-toughness high-thermal-conductivity thermal interface composite material according to claim 4, characterized in that, The synthesis of the ionic liquid additive with the structure of formula (I-II) comprises the following specific steps: The acetonitrile solution A of chloromethyl ether is added dropwise into the acetonitrile solution B of the intermediate product shown in formula (III), and after reaction at 60-90℃ for 12-24h, the ionic liquid additive with the structure shown in formula (I-II) is obtained after post-treatment; the molar ratio between the intermediate product shown in formula (III) and chloromethyl ether is 1:1.0-5.0; 。 6. The method for preparing the high-toughness, high-thermal-conductivity thermal interface composite material as described in claim 5, characterized in that, In the synthesis step of the ionic liquid additive with the structure of formula (I-II), the post-treatment method is as follows: the reaction solution is evaporated under reduced pressure to remove the solvent acetonitrile, the remaining mixture is washed with ether three times, and the solvent is evaporated under reduced pressure to dryness, thereby obtaining the ionic liquid additive with the structure shown in formula (I-II).

7. The method for preparing the high-toughness, high-thermal-conductivity thermal interface composite material as described in claim 4, characterized in that, The intermediate product shown in formula (III) is prepared as follows: pyrrolidine is stirred with KOH in CH3CN at 25℃ for 3h, then 1-chloromethyl ether is added to the mixture, and the reaction is continued under reflux conditions for 48h; the reaction mixture is evaporated under reduced pressure to remove the volatile solvent CH3CN, CH2Cl2 is added to the residue, extracted with water three times, and the organic phase is thoroughly dried with anhydrous Na2SO4; the collected organic phase filtrate is evaporated under reduced pressure to remove the solvent, then washed with ether three times, and the obtained solid product is dried in a dynamic vacuum oven at 45℃ for 24h to obtain the intermediate product shown in formula (III).

8. The method for preparing the high-toughness, high-thermal-conductivity thermal interface composite material as described in claim 4, characterized in that, In the electrodepositing step, the length of the ITO conductive glass is 5-50 cm, the width is 3-20 cm, the thickness is 0.5-5 mm, and the square resistance is 1-100 Ω / cm 2 ; the distance between the cathode and the anode is 0.02-1.0 cm; the concentration of the ionic liquid additive in the electrolyte is 10-200 mg / mL, the concentration of the metal nitrate is 50-150 mg / mL, and the total amount of the electrolyte is 50-300 mL; the electrodepositing voltage is 5-20 V, and the current density is 10-100 mA / cm 2 .

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