WO2017036082A1

WO2017036082A1 - High thermal conductivity polymer composite material, preparation method therefor and use thereof

Info

Publication number: WO2017036082A1
Application number: PCT/CN2016/072211
Authority: WO
Inventors: 孙蓉; 曾小亮; 王芳芳; 许建斌
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2015-08-31
Filing date: 2016-01-26
Publication date: 2017-03-09
Also published as: CN105062007A; CN105062007B

Abstract

A high thermal conductivity polymer composite material comprises a polymer matrix and three-dimensional boron nitride filled in the polymer matrix. The volumetric fraction of the three-dimensional boron nitride in the high thermal conductivity polymer composite material is 5-50%. According to the high thermal conductivity polymer composite material, the three-dimensional boron nitride is used to construct a three-dimensional network structure in the polymer matrix, and a heat conductive path is formed in the polymer matrix. Thus, the high thermal conductivity polymer composite material has a high heat conductive coefficient, and the condition of the preparation method therefor is moderate and easy to control, and the technology is simple, safe and environmentally friendly.

Description

Description: High thermal conductivity polymer composite material and preparation method and application thereof

[0001] The invention belongs to the technical field of thermal conductive composite materials, and particularly relates to a high thermal conductivity polymer composite material and a preparation method and application thereof.

Background technique

[0002] With the rapid development of electronic technology, the power and integration of electronic devices are increasing. Since 1959, the feature size of devices has been decreasing, and has been developed from micron to submicron. It is increasing at a high speed of 40 to 50% per year, which makes people's attention gradually shift from macroscopic objects to micro-scale devices. Especially in recent years, the rapid development of flexible electronics has greatly promoted this research boom. In electronic equipment, a considerable part of the power loss is converted into heat, so any microelectronic component with a certain resistance is an internal heat source component for the running microelectronic device. The increase of equipment temperature and the increase of thermal stress pose a serious threat to the reliability of microelectronic equipment. Thermal failure has become one of the most important failure modes in electronic packaging.

[0003] Conventional thermal materials such as metals, metal oxides, nitride ceramics, and other non-metallic materials have been unable to meet the requirements of modern electronic technology development due to their performance limitations. There is an urgent need to develop new high thermal conductivity polymer composite materials to meet industrial development requirements.

[0004] Since the beginning of the 1990s, the preparation and application of polymer/thermally conductive ceramic composites has attracted extensive attention in the academic and industrial circles. Previous studies have shown that the improvement of thermal conductivity of composite materials mainly depends on the type, content, particle size and shape of the thermally conductive ceramics, and the heterogeneous compatibility of the ceramic particles with the polymer materials. However, most of the current research results have a thermal conductivity of less than 5 W/mK, and the thermal conductivity of the highly conductive epoxy molding compound that has been commercialized is only about 4 W/mK. These findings indicate that it is difficult to form a thermally conductive network in a polymer-based composite by simply adding a highly thermally conductive ceramic powder, and it is difficult to prepare a polymer-based composite having a high thermal conductivity.

[0005] In addition, current three-dimensional boron nitride is usually prepared by chemical vapor deposition. Specifically, the precursor of the boron nitride is attached to the template (three-dimensional structure nickel or graphite) of the three-dimensional structure at a high temperature. After the reaction is completed, the template is removed by chemical etching to obtain a three-dimensional structure of boron nitride. [0006] For example, the Nanjing University of Aeronautics and Astronautics uses a foam metal as a template to obtain a three-dimensional boron nitride foam having excellent properties such as low density and high thermal stability by chemical vapor deposition and chemical etching. However, it has been found that the network of the foam metal prepared by the method has a pore size of several hundred micrometers, and the three-dimensional boron nitride foam prepared by using the template has a low bulk density, which is disadvantageous for its macro preparation. Another method for preparing three-dimensional boron nitride disclosed in Fudan University is to use a chemical vapor deposition method to prepare a porous metal by a high-temperature reduction reaction using a transition metal elemental powder or a transition metal-containing compound as a catalyst. The catalyst skeleton; the hexagonal boron nitride is grown by chemical vapor deposition to obtain a hexagonal boron nitride powder with a catalyst skeleton and three-dimensional boron nitride. Although the method uses a transition metal element or a transition metal element-containing compound as a raw material, and replacing the conventional metal foam template with a porous catalyst template, the three-dimensional boron nitride obtained by using the foam metal as a catalytic skeleton has a higher porosity; Still using a combination of traditional chemical vapor deposition and chemical etching, resulting in a three-dimensional structure of boron nitride brittle, poor mechanical strength

[0007] Therefore, current chemical vapor deposition methods involve high temperature reactions (1000 ° C) and the use of corrosive and explosive gases, severely limiting the use of three-dimensional boron nitride.

technical problem

[0008] The object of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to provide a high thermal conductivity polymer composite material and a preparation method thereof, so as to solve the problem that the existing polymer/thermal conductive ceramic composite material is difficult to be in a polymer matrix composite material. It is difficult to effectively improve the thermal conductivity of polymer/thermally conductive ceramic composites by forming a heat conduction network.

Another object of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to provide an application of the high thermal conductive polymer composite material of the present invention to solve the problem that the existing polymer/thermal conductive ceramic composite material is used due to low thermal conductivity. Limited technical issues.

Problem solution

Technical solution

[0010] In order to achieve the above object of the invention, in one aspect of the invention, a highly thermally conductive polymer composite is provided

The high thermal conductivity polymer composite material comprises a polymer matrix and three-dimensional boron nitride filled in the polymer matrix, and the volume fraction of the three-dimensional boron nitride in the high thermal conductivity polymer composite is 5 -50%. [0011] According to another aspect of the present invention, a method for preparing a highly thermally conductive polymer composite of the present invention is provided

The preparation method of the high thermal conductive polymer composite material comprises the following steps:

[0012] The boron nitride nanosheet, water and water-soluble polymer are mixed at a mass ratio of 1: (1-50): 100 to obtain a mixture solution;

[0013] The mixture solution is subjected to a freeze treatment to form a frozen mixture, and the frozen mixture is subjected to freeze-drying treatment to obtain a three-dimensional boron nitride precursor;

[0014] The three-dimensional boron nitride precursor is subjected to sintering heat treatment to obtain three-dimensional boron nitride;

[0015] The three-dimensional boron nitride is immersed in a liquid prepolymer, subjected to a bubble removal treatment, and then subjected to a heat curing treatment to obtain a highly thermally conductive polymer composite material.

[0016] According to still another aspect of the present invention, there is provided a method of applying the highly thermally conductive polymer composite of the present invention, in particular, the high thermal conductivity polymer composite in the field of motors, electronic packaging, LED packaging, and aerospace. Applications in the military field.

Advantageous effects of the invention

Beneficial effect

[0017] Compared with the prior art, the above-mentioned high thermal conductive polymer composite material of the present invention uses a three-dimensional boron nitride to construct a stable three-dimensional network structure in a polymer matrix, and establishes a heat conduction channel in the polymer matrix, thereby imparting the present invention. High thermal conductivity polymer composites have high thermal conductivity.

[0018] The method for preparing the high thermal conductivity polymer composite material of the present invention can be thermally cured by using three-dimensional boron nitride as a three-dimensional network structure and a liquid prepolymer, thereby realizing establishment of a heat conduction channel in the polymer body to impart high in the present invention. Thermally conductive polymer composites have a high thermal conductivity. At the same time, using boron nitride nanosheets and water-soluble polymers as raw materials, the three-dimensional boron nitride is obtained by the ice template method, the preparation process is safe and environmentally friendly, the solvent used is an aqueous solution, and no organic solvent is involved; and the reaction conditions are mild and easy to control. The process is simple, effectively avoids the use of harsh conditions such as high-temperature reaction and corrosive and explosive gas, such as the preparation of three-dimensional boron nitride by chemical vapor deposition, and reduces the three-dimensional boron nitride and the high thermal conductivity of the invention. The production cost of polymer composites. Secondly, the preparation of three-dimensional boron nitride has low density, high porosity, excellent three-dimensional structure size, good mechanical properties, and improved stability of the three-dimensional network structure in the high thermal conductivity polymer composite of the present invention, so that the present invention has high thermal conductivity. The polymer composite has stable thermal conductivity.

[0019] It is because of the high thermal conductivity polymer composite material of the invention has high thermal conductivity and stable thermal conductivity. Therefore, it can be more widely used in the fields of electric motors, electronic packaging, LED packaging, and aerospace and military.

Brief description of the drawing

DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a flow chart of a method for preparing a highly thermally conductive polymer composite material according to an embodiment of the present invention;

2 is a scanning electron microscope (SEM) image of three-dimensional boron nitride prepared in Example 1.

Embodiments of the invention

[0023] In order to make the technical problems, technical solutions, and advantageous effects to be solved by the present invention more clearly, the present invention will be further described in detail below with reference to the embodiments and drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] Embodiments of the present invention provide a highly thermally conductive polymer composite having a thermally conductive network structure. In one embodiment, the high thermal conductivity polymer composite comprises a polymer matrix and three-dimensional boron nitride filled in the polymer matrix, and the three-dimensional boron nitride is in the high thermal conductivity polymer composite. The volume fraction is 5 - 50%. In this way, the high thermal conductivity polymer composite uses three-dimensional boron nitride to construct a three-dimensional network structure in the polymer matrix, and establishes a heat conduction channel in the polymer matrix, thereby imparting high thermal conductivity to the highly thermally conductive polymer composite of the present invention. In addition to imparting high thermal conductivity to the high thermal conductivity polymer composite, the volumetric content of the three-dimensional boron nitride can be relatively reduced. It has been determined that the high thermal conductivity polymer composite provided by the embodiment of the present invention has a thermal conductivity of 0.3-10 W/m.K.

[0025] In an embodiment, the density of the three-dimensional boron nitride in the high thermal conductive polymer composite provided by the embodiment of the present invention is controlled to be 1.0 to 100 mg/cm 3 ; in another embodiment, the three-dimensional nitriding The pore diameter of boron is 2 to 200 μηι. By controlling the density and the aperture of the three-dimensional boron nitride, the three-dimensional network structure of the three-dimensional boron nitride has a better thermal conductivity and a more stable structure, thereby imparting the high thermal conductivity polymer composite provided by the embodiments of the present invention. High thermal conductivity and thermal stability.

In one embodiment, the polymer is at least one liquid prepolymer of liquid epoxy resin, liquid cyanate, liquid bismaleimide, liquid polyimide prepolymer The formed polymer is heat cured.

[0027] In a further embodiment, the liquid prepolymer is thermally cured into a stepwise heat curing process, the first step The temperature of the ladder heat curing treatment is 80-140 ° C, and the temperature between the turns is 0.5-2 h; the temperature of the second step heat curing treatment is 1 40-160 ° C, and the temperature between the turns is 0.5-2 h; The temperature is 160-200 ° C, and the daytime is 0.5-2 h.

[0028] In a specific embodiment, the heat curing treatment is a stepwise heat curing treatment, the temperature of the first step heat curing treatment is 140 ° C, the time between the turns is 2 h; the temperature of the second step heat curing treatment is 160 ° C, the daytime is 2h; the third step heat curing treatment temperature is 200 °C, and the daytime is 2h.

[0029] By selecting the kind of the above polymer and controlling the curing treatment conditions of the liquid prepolymer, the three-dimensional boron nitride can establish a high heat rate and a high stable heat conduction channel in the selected polymer, and the invention is provided. EXAMPLES High thermal conductivity polymer composites with high thermal conductivity and high stability can moderately reduce the volume content of three-dimensional boron nitride.

[0030] Therefore, the high thermal conductivity polymer composite material in each of the above embodiments uses a three-dimensional boron nitride to construct a three-dimensional network structure in a polymer matrix, and a heat conduction channel having high thermal conductivity and high stability is established in the polymer matrix. Therefore, the high thermal conductive polymer composite material of the present invention has a high thermal conductivity, and the thermal conductivity is more than three times higher than that of the conventional polymer/thermal conductive ceramic composite, as described in the specific examples below. In addition, the volume content of the three-dimensional boron nitride can be relatively reduced.

Accordingly, embodiments of the present invention provide a method of preparing one of the highly thermally conductive polymer composites described above. The process steps for preparing a high thermal conductivity polymer composite material according to an embodiment of the present invention are shown in FIG. 1 and include the following steps:

[0032] Step S01: mixing boron nitride nanosheets, water and water-soluble polymer according to a mass ratio of 1: (1-50): 100 to obtain a mixture solution;

[0033] Step S02: The mixture solution prepared in step S01 is subjected to freeze treatment to form a frozen mixed liquid, and the frozen mixed liquid is subjected to freeze-drying treatment to obtain a three-dimensional boron nitride precursor;

[0034] Step S03: performing the sintering heat treatment on the three-dimensional boron nitride precursor prepared in step S02 to obtain three-dimensional boron nitride;

[0035] Step S04: The three-dimensional boron nitride prepared in the step S03 is immersed in the liquid prepolymer, subjected to a heat removal treatment after the bubble removing treatment, to obtain a highly thermally conductive polymer composite material.

[0036] Specifically, in the above step S01, after the boron nitride nanosheet, water and the water-soluble polymer are mixed at a predetermined ratio, the boronized nanosheet forms a uniform dispersion system. Therefore, in step S01 The mixing treatment may be a conventional treatment such as stirring, sonication or the like.

[0037] In another embodiment, the water-soluble polymer in the step S01 is at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyacrylamide, and polyvinylpyrrolidone. The polymer can not only be effectively dissolved in water, but also can effectively ensure the uniform distribution of the boron nitride nanosheets in the subsequent final dried three-dimensional boron nitride precursor, and is favorable for the formation of three-dimensional boron nitride.

[0038] In a preferred embodiment, the water in step S01 is selected from deionized water.

[0039] In a preferred embodiment, the diameter of the boron nitride nanosheet in step S01 and the selection of the water-soluble polymer are set according to the above conditions to improve the stability of the dispersion solution of the mixture solution and the boron nitride nanometer. Dispersion uniformity of the sheet.

[0040] In a further embodiment, the boron nitride nanosheets in the above step S01 are prepared as follows:

[0041] SOU: ultrasonic mixing treatment is carried out by mixing micron boron nitride with an organic solvent at a mass ratio of 1: (50-100) to obtain an initial mixed solution;

[0042] S012: performing solid-liquid separation on the primary mixed liquid to obtain the boron nitride nanosheet.

[0043] wherein, as an embodiment, the micron boron nitride in the step S011 has a particle diameter of 2 μm to 18 μm.

In another embodiment, the organic solvent is at least one of isopropyl alcohol, hydrazine, Ν'-dimethylformamide or hydrazine-methylpyrrolidone. In still another embodiment, in the ultrasonic mixing processing operation, the ultrasonic power is 100 - 1000 W, and the ultrasonic time is 12 to 24 h. By controlling the micron boron nitride particle size, the organic solvent and the ultrasonic mixing process parameters, the micron boron nitride is sufficiently stripped to form a boron nitride nanosheet.

[0044] The solid-liquid separation in the step S012 can achieve separation of the boron nitride nanosheet from the organic solvent by a conventional method. In one embodiment, the solid-liquid separation is centrifugal separation, and the centrifugal rate is 1000.

Rpm~5000rpm, centrifuged for 10-30 minutes.

[0045] In the above step S02, the freezing treatment of the mixed solution prepared in the step S01 is to freeze the water in the mixed solution, which is advantageous for solidification of the polymer. Therefore, in one embodiment, the freezing temperature of the freezing treatment is controlled to be -20 to -40 ° C, and the freezing time is 12 to 24 hours. By controlling the temperature of the freezing process and the control of the crucible, not only can the water be frozen to facilitate sublimation in the subsequent freeze-drying process, but more importantly, the control of the temperature and the inter-turn can cause the boron nitride nanosheet to solidify. The mixed solution can be uniformly dispersed to avoid agglomeration and collapse during the subsequent freeze-drying process, thereby ensuring uniform distribution of the boron nitride nanosheet in the three-dimensional boron nitride precursor. [0046] The degree of vacuum of the freeze-drying treatment of the mixed solution is -20 Pa~-100 Pa, and the freezing temperature is -50-0 °C

In one embodiment, the freeze-drying treatment has a vacuum of -40 Pa and a freezing temperature of -50 °C. By controlling the freeze-drying temperature and the crucible, the boron nitride nanosheets are uniformly distributed in the final dry three-dimensional boron nitride precursor while effectively removing moisture.

[0047] On the basis of the above step S02, after the three-dimensional boron nitride precursor obtained in step S03 is subjected to the sintering heat treatment in step S03, the water-soluble polymer in the three-dimensional boron nitride precursor is removed, thereby forming a porous structure. Three-dimensional boron nitride. In one embodiment, the temperature of the sintering heat treatment is 800-1200 ° C, and the sintering time is 4-8 h. In a specific embodiment, the temperature of the sintering heat treatment is

1000 ° C, sintering time is 4h. The sintering heat treatment effectively removes the polymer and imparts a stable three-dimensional structure to the three-dimensional boron nitride precursor.

[0048] It has been determined that the sintered three-dimensional boron nitride has a density of 1.0 to 100 mg/cm 3 and a pore diameter of 2 to 200 μm.

The density and the aperture of the three-dimensional boron nitride also make the three-dimensional network structure of the three-dimensional boron nitride have better thermal conductivity and more stable structure, thereby imparting high thermal conductivity to the high thermal conductivity polymer composite provided by the embodiments of the present invention. And thermal stability.

[0049] In the above step S04, after the three-dimensional boron nitride is immersed in the liquid prepolymer, the liquid prepolymer coats the three-dimensional boron nitride and is filled into the porous structure of the three-dimensional boron nitride. In one embodiment, the liquid prepolymer polymer is at least one of a liquid epoxy resin, a liquid cyanate ester, a liquid bismaleimide, and a liquid polyimide prepolymer. The liquid prepolymer polymer selected not only has good fluidity, but also heat-cured to enable three-dimensional boron nitride to establish a high heat rate and a highly stable heat conduction channel in the polymer, thereby imparting high thermal conductivity polymerization in the embodiment of the present invention. The composite material has high thermal conductivity and high stability, and can simultaneously reduce the volume content of three-dimensional boron nitride.

[0050] In order to avoid mixing air bubbles in the liquid prepolymer, and to enable the liquid prepolymer to be sufficiently filled into the porous structure of the three-dimensional boron nitride, to use the thermal conductivity of the final high thermal conductivity polymer composite, a bubble removal treatment method is adopted. Process it. After the three-dimensional boron nitride is immersed in the liquid prepolymer, the bubble removal treatment is performed first, followed by thermal curing treatment.

[0051] In order to further improve the high heat rate and high stability of the heat conduction channel that the three-dimensional boron nitride can establish in the polymer, in one embodiment, the heat curing treatment of the liquid prepolymer polymer is set as above The stepped thermal curing process described herein, such as a three-step thermal curing process, the first step thermal curing process The temperature is 80-140 ° C, 0.5-2 h between turns; the second step heat curing temperature is 140-160 ° C, the daytime is 0.5-2 h; the third step heat curing temperature is 160-200 ° C, daytime is 0.5-2h. In a specific embodiment, the heat curing treatment is a stepwise heat curing treatment, the temperature of the first step heat curing treatment is 140 ° C, the time between the turns is 2 h; the temperature of the second step heat curing treatment is 160 ° C, The interval is 2h; the temperature of the third step heat curing treatment is 200 ° C, and the temperature between the turns is 2 h.

[0052] It can be seen from the above that the preparation method of the high thermal conductivity polymer composite material of the embodiment of the present invention can be performed by thermally curing a three-dimensional boron nitride as a three-dimensional network structure and a liquid prepolymer, thereby realizing heat conduction in the polymer body. The channels thereby impart high thermal conductivity to the highly thermally conductive polymer composite of the present invention.

[0053] In addition, using boron nitride nanosheets and water-soluble polymers as raw materials, the three-dimensional boron nitride is obtained by the ice template method, the preparation process is safe and environmentally friendly, the solvent used is an aqueous solution, and no organic solvent is involved; and the reaction conditions are mild, Easy to control, the process is simple, effectively avoiding the use of harsh conditions such as high temperature reaction and corrosive and explosive gases, such as the conventional chemical vapor deposition method for preparing three-dimensional boron nitride, and simultaneously reducing three-dimensional boron nitride and the present invention. Production cost of high thermal conductivity polymer composites.

[0054] Secondly, the preparation of three-dimensional boron nitride has low density, high porosity, excellent three-dimensional structure size, good mechanical properties, and improved stability of the three-dimensional network structure in the high thermal conductivity polymer composite of the present invention. The invention discloses that the high thermal conductivity polymer composite material has stable thermal conductivity.

[0055] As described above, the high thermal conductivity polymer composite provided by the embodiments of the present invention has high thermal conductivity, excellent thermal conductivity stability, mild preparation conditions, environmental protection and safety, and moderately saves three-dimensional nitrogen. The amount of boron is used. Therefore, the high thermal conductivity polymer composite provided by the embodiments of the present invention can be widely applied in the fields of electric motors, electronic packaging, LED packaging, and aerospace military.

[0056] The present invention will now be further described in detail by taking a highly thermally conductive polymer composite material and its preparation method as an example.

Embodiment 1

[0058] A high thermal conductivity polymer composite material and a preparation method thereof. The highly thermally conductive polymer composite material provided in this Example 1 was prepared as follows:

[0059] S11: mixing boron nitride nanosheets, deionized water, and polyethylene glycol according to a mass ratio of 1:50:100; [0060] S12: mixing the mixture of step S11 in a refrigerator at -20 ° C Frozen at 12h for a frozen mixture at temperature

The frozen mixture is subjected to a freeze vacuum drying process with a vacuum of -40 Pa and a freezing temperature of -50 °C. Obtaining a three-dimensional boron nitride precursor;

[0061] S13: a three-dimensional boron nitride precursor high-temperature sintering operation process, the sintering temperature is 1000 ° C, the sintering time is 4h, to obtain three-dimensional boron nitride;

[0062] S14: impregnating the three-dimensional boron nitride with the liquid epoxy resin system, removing the bubbles under vacuum, and using the stepwise heat curing to obtain a high thermal conductive polymer composite material, that is, thermally curing to obtain three-dimensional boron nitride. - polymer composites, wherein the curing temperatures are 140 ° C, 160 ° C and 200 ° C, respectively, and the daytime is 2 h

The three-dimensional boron nitride prepared in the first embodiment was subjected to scanning electron microscopy (SEM) microscopic analysis, and its microscopic cross section is shown in Fig. 2, which is a porous structure having a density of 21 mg/cm3; and a pore diameter of 100 μm.

[0064] The high thermal conductivity polymer composite prepared in the first embodiment was measured for thermal conductivity, and the thermal conductivity was measured.

7 W/m.K, in addition, the volume fraction of three-dimensional boron nitride in the high thermal conductivity polymer composite was 5%.

Example 2

[0066] A highly thermally conductive polymer composite material and a method of preparing the same. The highly thermally conductive polymer composite material provided in this Example 2 was prepared as follows:

[0067] S21: mixing boron nitride nanosheets, deionized water, and polyvinyl alcohol according to a mass ratio of 1:30:100; [0068] S22: mixing the mixture of step S21 in a refrigerator at -20 ° C Under, frozen for 12h to get a frozen mixture

The frozen mixture is subjected to a freeze vacuum drying process with a vacuum of -40 Pa and a freezing temperature of -50 ° C to obtain a three-dimensional boron nitride precursor;

[0069] S23: a high-temperature sintering operation of the three-dimensional boron nitride precursor, the sintering temperature is 1000 ° C, and the sintering time is 4 h to obtain three-dimensional boron nitride;

[0070] S24: impregnating the three-dimensional boron nitride with the liquid cyanate, removing the bubbles under vacuum, and using the stepwise heat curing to obtain a highly thermally conductive polymer composite, that is, thermally curing to obtain three-dimensional boron nitride- The polymer composite material, wherein the curing temperatures are 140 ° C, 160 ° C and 200 ° C, respectively, and the daytime is 2 h.

The three-dimensional boron nitride prepared in the second embodiment was subjected to scanning electron microscopy (SEM) microscopic analysis, and its microscopic cross section is similar to that shown in FIG. 2, which is a porous structure having a density of 30 mg/cm 3 and a pore diameter of 150 μm.

[0072] The high thermal conductivity polymer composite prepared in the second embodiment was measured for thermal conductivity, and the thermal conductivity was measured.

8W/m.K, in addition, the volume fraction of three-dimensional boron nitride in the high thermal conductivity polymer composite was 30%.

Example 3 [0074] A high thermal conductivity polymer composite material and a preparation method thereof. The highly thermally conductive polymer composite provided in Example 3 was prepared as follows:

S31: mixing boron nitride nanosheets, deionized water and polyvinylpyrrolidone according to a mass ratio of 1:20:100.

[0076] S32: The mixture of the step S31 is frozen in a refrigerator at a temperature of -20 ° C for 12 hours to obtain a frozen mixture, and the frozen mixture is subjected to a freeze vacuum drying process, the degree of vacuum is -40 Pa, and the freezing temperature is - At 50 ° C, a three-dimensional boron nitride precursor is obtained;

[0077] S33: a three-dimensional boron nitride precursor high-temperature sintering operation process, the sintering temperature is 1000 ° C, the sintering time is 4h, to obtain three-dimensional boron nitride;

[0078] S34: impregnating three-dimensional boron nitride with liquid bismaleimide, removing bubbles under vacuum, and using the stepwise thermal curing to obtain a highly thermally conductive polymer composite, that is, thermally curing to obtain three-dimensional nitrogen. Boron-polymer composites, wherein the curing temperatures are 140 ° C, 160 ° C and 200 ° C, respectively, 2 h

The three-dimensional boron nitride prepared in the third embodiment was subjected to scanning electron microscopy (SEM) microscopic analysis, and its microscopic cross section is similar to that shown in FIG. 2, which is a porous structure having a density of 45 mg/cm 3 and a pore diameter of 200 μm.

[0080] The high thermal conductivity polymer composite prepared in Example 3 was measured for thermal conductivity, and the thermal conductivity was measured.

2W/m.K, in addition, the volume fraction of three-dimensional boron nitride in the high thermal conductivity polymer composite was measured to be 40%.

Example 4

[0082] A high thermal conductivity polymer composite material and a preparation method thereof. The highly thermally conductive polymer composite material provided in this Example 4 was prepared as follows:

S41: mixing boron nitride nanosheets, deionized water, and polyacrylamide according to a mass ratio of 1:1:100; [0084] S42: placing the mixture of step S41 in the refrigerator at -20 ° At a temperature of C, the frozen mixture was obtained by freezing for 12 hours, and the frozen mixture was subjected to a freeze vacuum drying process with a vacuum of -40 Pa and a freezing temperature of -50.

. C, obtaining a three-dimensional boron nitride precursor;

[0085] S43: a high-temperature sintering operation of the three-dimensional boron nitride precursor, the sintering temperature is 1000 ° C, and the sintering time is 4 h to obtain three-dimensional boron nitride;

[0086] S44: impregnating the three-dimensional boron nitride with the liquid polyimide prepolymer, and removing bubbles under vacuum. The mixture is thermally cured by stepwise to obtain a highly thermally conductive polymer composite, that is, thermally cured to obtain three-dimensional nitrogen. Boron-polymer composite, wherein the curing temperature is 140 ° C, 160

°. And 200°. , the daytime is 2h.

The three-dimensional boron nitride prepared in the fourth embodiment was subjected to scanning electron microscopy (SEM) microscopic analysis, and its microscopic cross section is similar to that shown in FIG. 2, which is a porous structure having a density of 50 mg/cm 3 and a pore diameter of 50 μm.

[0088] The high thermal conductivity polymer composite prepared in the fourth embodiment was measured for thermal conductivity, and the thermal conductivity thereof was measured.

0W/m.K, in addition, the volume fraction of three-dimensional boron nitride in the high thermal conductivity polymer composite was measured to be 50%.

Comparative Example 1

[0090] The boron nitride nanosheets are dispersed in a liquid epoxy resin by ultrasonic technology, and bubbles are removed under vacuum. The mixture was subjected to stepwise heat curing at a curing temperature of 140 ° C, 160

And 200, both are 2h. Thermal curing gives boron nitride nanosheet-polymer composites. The volume fraction of the boron nitride nanosheet is 5%, and the thermal conductivity of the composite is only 0.16 W/m.K.

Comparative Example 2

[0092] The boron nitride nanosheets are dispersed in a liquid cyanate by ultrasonic technology, and bubbles are removed under vacuum. The mixture was subjected to stepwise heat curing at a temperature of 140 ° C, 160 ° C and 200 ° C, respectively, for 2 h. Thermal curing gives boron nitride nanosheet-polymer composites. The volume fraction of boron nitride nanosheets is controlled to 20%, and the thermal conductivity of the composite is only 0.3 W/m.K.

Comparative Example 3

[0094] The boron nitride nanosheets were dispersed in liquid bismaleimide by ultrasonic technique, and bubbles were removed under vacuum. The mixture was subjected to stepwise heat curing at a temperature of 140 ° C, 160 ° C and 200 ° C, respectively, for 2 h. Thermal curing gives boron nitride nanosheet-polymer composites. The volume fraction of boron nitride nanosheets is controlled to 30%, and the thermal conductivity of the composite is only 0.4 W/m.K.

Comparative Example 4

[0096] The boron nitride nanosheets were dispersed in a liquid polyimide prepolymer by ultrasonic technology, and the bubbles were removed under vacuum. The mixture was subjected to stepwise heat curing at 140 ° C, 160 ° C and 200 ° C, respectively, for 2 h. Thermal curing gives boron nitride nanosheet-polymer composites. The volume fraction of the boron nitride nanosheet is controlled to 50%, and the thermal conductivity of the composite is only 2.8 W/m.K.

[0097] It can be seen from the above that the three-dimensional boron nitride provided by the embodiment of the present invention constructs a three-dimensional network structure in a polymer matrix, and establishes a heat conduction channel in the polymer matrix, thereby imparting the high thermal conductive polymer composite material of the present invention. Has a high thermal conductivity.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

Claim

A highly thermally conductive polymer composite characterized by comprising: a polymer matrix and three-dimensional boron nitride filled in the polymer matrix, and the three-dimensional boron nitride is in the high thermal conductivity polymer composite The volume fraction is 5 - 50%.

The highly thermally conductive polymer composite according to claim 1, wherein: said high thermal conductive polymer composite has a thermal conductivity of 0.3 to 10 W/m.K.

The high thermal conductivity polymer composite according to claim 1 or 2, wherein: said three-dimensional boron nitride has a density of 1.0 to 100 mg/cm3; and/or

The three-dimensional boron nitride has a pore diameter of 2 to 200 μm; and/or

The polymer is a polymer formed by heat curing of at least one liquid prepolymer of liquid epoxy resin, liquid cyanate, liquid bismaleimide, liquid polyimide prepolymer according to the right The high thermal conductivity polymer composite according to claim 3, wherein: the thermal curing treatment is a step thermal curing treatment, the first step thermal curing treatment temperature is 80-140 ° C, and the daytime is 0.5-2 h; The temperature of the second step heat curing treatment is 140-160 ° C, and the temperature between the turns is 0.5-2 h; the temperature of the third step heat curing treatment is 160-200 ° C, and the daytime is 0.5-2 h. A method for preparing a highly thermally conductive polymer composite material, comprising the steps of:

Boron nitride nanosheets, water and water-soluble polymer are mixed at a mass ratio of 1: (1-50): 100 to obtain a mixture solution;

The mixture solution is subjected to a freeze treatment to form a frozen mixture, and the frozen mixture is subjected to freeze-drying treatment to obtain a three-dimensional boron nitride precursor;

The three-dimensional boron nitride precursor is subjected to sintering heat treatment to obtain three-dimensional boron nitride; the three-dimensional boron nitride is immersed in a liquid prepolymer, and subjected to a heat removal treatment after defoaming treatment to obtain a high thermal conductive polymer composite. material.

The high thermal conductivity polymer composite according to claim 5, wherein: said three-dimensional boron nitride has a density of 1.0 to 100 mg/cm 3 ; and/or

The three-dimensional boron nitride has a pore diameter of 2 to 200 μm; and/or

The liquid prepolymer polymer is a liquid epoxy resin, a liquid cyanate, a liquid bismalediol At least one of an imine, a liquid polyimide prepolymer.

[Claim 7] The high thermal conductive polymer composite according to claim 6, wherein: the thermal curing treatment is a step thermal curing treatment, and the temperature of the first step thermal curing treatment is 80-140 ° C, 0.5-2h for the second step; 140-160°C for the second step heat curing, 0.5-2h for the second step; 160-200°C for the third step heat curing treatment, 0.5-2h for the daytime .

[Claim 8] The preparation method according to any one of claims 5-7, wherein: the boron nitride nanosheet has a diameter of 100 nm to 600 nm; and/or

The water-soluble polymer is at least one of polyvinyl alcohol, polyethylene glycol, polyacrylamide, and polyvinylpyrrolidone.

[Claim 9] The preparation method according to any one of claims 5 to 7, wherein: the freezing temperature of the freezing treatment is -20 to -40 ° C, and the freezing time is 12 to 24 hours; and/or The freeze-drying treatment has a vacuum of -20 Pa to -100 Pa and a freezing temperature of -50 to 0 ° C; and/or

The sintering heat treatment temperature is 800-1200 ° C, and the sintering time is 4-8 h.

[Claim 10] The use of the highly thermally conductive polymer composite according to any of claims 1-4 in the field of electrical machinery, electronic packaging, LED packaging, and aerospace military.