High-thermal-conductivity biaxially oriented polyamide film

Abstract

The invention discloses a high-thermal-conductivity biaxially-oriented polyamide film which is of a three-layer structure and sequentially comprises an upper surface layer, a middle layer and a lower surface layer from top to bottom. The upper surface layer is prepared from the following raw materials in parts by weight: 1 to 8 parts of anti-sticking master batch, 5 to 20 parts of heat-conducting material, 5 to 50 parts of heat-conducting polyamide 6 and 22 to 89 parts of polyamide 6; the middle layer is prepared from the following raw materials in parts by weight: 5-25 parts of a heat-conducting material, 5-60 parts of heat-conducting polyamide 6 and 15-90 parts of polyamide 6; the lower surface layer is prepared from the following raw materials in parts by weight: 1 to 8 parts of anti-sticking master batch, 5 to 20 parts of heat-conducting material, 5 to 50 parts of heat-conducting polyamide 6 and 22 to 89 parts of polyamide 6; the heat conduction material is prepared from the following raw materials in parts by weight: 0.5 to 15 parts of nano ultrathin two-dimensional boron nitride, 0.5 to 8 parts of branched polyethyleneimine-block-polyethylene glycol, 0.1 to 10 parts of 4, 4 '-methylene bis (cyclohexyl isocyanate) and 67 to 98.9 parts of polyamide 6. By adding the heat conduction material added with the nanometer ultrathin two-dimensional boron nitride, the heat conduction capability and the mechanical property of the film are effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thin film materials, and particularly relates to a high thermal conductivity biaxially stretched polyamide film. Background Art

[0002] With the development of miniaturization and high power density of electronic devices, higher requirements are put forward for the thermal management performance of materials. As a key component for heat dissipation, the thermal conductive thin film material needs to have high thermal conductivity, light weight, flexibility and processing adaptability. Polyamide (such as PA6) is often used as a matrix material due to its excellent mechanical properties and processability, but its intrinsic thermal conductivity is low (usually <0.3 W / (m·K)), making it difficult to meet the high heat dissipation requirements. Therefore, improving the thermal conductivity of composite materials by adding thermal conductive fillers (such as boron nitride, graphene, etc.) has become a research hotspot.

[0003] Currently, boron nitride (BN) is widely used due to its high thermal conductivity (in-plane thermal conductivity can reach 300 W / (m·K)) and insulation, but there are the following bottlenecks: 1) Poor filler dispersion and interfacial compatibility: Conventional BN particles are prone to agglomeration, and the interfacial bonding with the polymer matrix is weak, resulting in discontinuous heat conduction paths. A high addition amount (usually >30 wt%) is required to significantly improve the thermal conductivity, but it will sacrifice the mechanical properties and processing fluidity of the material. 2) The structure thickness limits the heat conduction efficiency: Commercially available BN is mostly micron-scale thick flakes or multi-layer stacked structures with a large thickness (>50 nm), which hinders the in-plane heat conduction path and makes it difficult to form an efficient three-dimensional heat conduction network. 3) Insufficient functional modification: Existing technologies mostly rely on physical blending or simple surface modification (such as silane coupling agents), and the chemical interaction between the modifier, BN and the matrix is limited, and phase separation is likely to occur under high temperature or stress.

[0004] The Chinese patent application with the application number CN202410874533.6 discloses a production method of a high - thermal - conductivity biaxially oriented nylon film. The nylon film includes a surface layer, an intermediate layer, and an inner layer. The surface layer is composed of MXD6, alumina, silicon carbide, coupling agent, and antioxidant; the intermediate layer is composed of PA6, carbon fiber coated with graphene oxide, maleic anhydride - grafted POE, and TPE; the inner layer is composed of PA6, boron nitride, large - particle - size magnesium hydroxide, and small - particle - size magnesium hydroxide. The nylon film designed in this way has good barrier properties and good thermal conductivity. Although this scheme combines the characteristics of various fillers through a layered design, there are still the following limitations: 1) High process complexity: The multi - layer co - extrusion process has strict requirements for equipment precision and parameter matching, increasing production costs and processing difficulties; 2) Insufficient filler synergy: Different thermal - conductive fillers (such as carbon fiber, BN, and magnesium hydroxide) are independently used in each layer, lacking a cross - layer interface collaborative thermal - conductive network, and the co - existence of multiple components may lead to interface compatibility problems; 3) Low utilization efficiency of boron nitride: The inner layer uses conventional boron nitride (without specifying an ultra - thin structure), and it is necessary to rely on the particle - size gradient filling of magnesium hydroxide to compensate for the thermal conductivity, resulting in a high total filler content (the total proportion of boron nitride + magnesium hydroxide in the inner layer > 25wt%), which may affect the flexibility, mechanical properties, and light transmittance of the film. In contrast, two - dimensional ultra - thin boron nitride (2D BN) is more suitable for constructing an efficient thermal - conductive network due to its single - layer / few - layer structure, high specific surface area, and active edge sites. However, the existing technology is still insufficient in its interface functionalization and performance regulation at low addition amounts.

[0005] In view of the above problems, there is an urgent need to develop a new type of thermal - conductive material that can achieve the unity of high thermal conductivity, strong interface bonding, and good processability at low addition amounts through structural design and interface synergy optimization. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a high - thermal - conductivity biaxially oriented polyamide film, aiming to break through the bottleneck of the existing technology and meet the requirements of high - end electronic packaging, flexible heat - dissipation films, and other fields.

[0007] The technical solution of the present invention is as follows:

[0008] The purpose of the present invention is to provide a high - thermal - conductivity biaxially oriented polyamide film. The film has a three - layer structure, which is the upper surface layer, the intermediate layer, and the lower surface layer from top to bottom in sequence;

[0009] The upper surface layer is composed of the following raw materials in parts by weight: 1 - 8 parts of anti - sticking masterbatch, 5 - 20 parts of thermal - conductive material, 5 - 50 parts of thermally conductive polyamide 6, and 22 - 89 parts of polyamide 6;

[0010] The intermediate layer is composed of the following raw materials in parts by weight: 5 - 25 parts of thermal - conductive material, 5 - 60 parts of thermally conductive polyamide 6, and 15 - 90 parts of polyamide 6;

[0011] The lower surface layer is composed of the following raw materials in parts by weight: 1 - 8 parts of anti - sticking masterbatch, 5 - 20 parts of heat - conducting material, 5 - 50 parts of heat - conducting polyamide 6, and 22 - 89 parts of polyamide 6;

[0012] Among them, the heat - conducting material is composed of the following raw materials in parts by weight: 0.5 - 15 parts of nano - ultra - thin two - dimensional boron nitride, 0.5 - 8 parts of branched polyethyleneimine - block - polyethylene glycol, 0.1 - 10 parts of 4,4'-methylenebis(cyclohexyl isocyanate), and 67 - 98.9 parts of polyamide 6.

[0013] Furthermore, the preparation process of the nano - ultra - thin two - dimensional boron nitride in the heat - conducting material is as follows:

[0014] S1: Ball - mill 1 - 20 parts of boron nitride powder;

[0015] S2: While stirring, add 80 - 99 parts of dimethylformamide solution to the ball - milled boron nitride obtained in step S1, and obtain a uniform suspension after ultrasonic dispersion;

[0016] S3: Add 1 - 15 parts of cetyltrimethylammonium bromide to the suspension obtained in step S2, stir evenly, and then react at 1.5 - 5 MPa and 100 - 190 °C for 5 - 50 h. After the reaction ends, cool to room temperature, and obtain a mixed solution after ultrasonic treatment and high - speed stirring;

[0017] S4: Centrifuge the mixed solution obtained in step S3, take the upper - layer dispersion liquid, wash it 3 - 6 times with deionized water, and perform vacuum drying to obtain the nano - ultra - thin two - dimensional boron nitride.

[0018] Furthermore, in step S1, the rotation speed of the ball - milling is 300 - 1000 r / min, and the ball - milling time is 1 - 10 h.

[0019] Furthermore, in step S2, the stirring speed is 100 - 500 r / min, and the ultrasonic dispersion time is 30 - 180 min.

[0020] Furthermore, in step S3, the ultrasonic power of the ultrasonic treatment is 100 - 600 W, and the time is 2 - 12 h.

[0021] Furthermore, in step S3, the speed of the high - speed stirring is 1000 - 5000 r / min, and the time is 1 - 6 h.

[0022] Furthermore, in step S4, the speed of the centrifugal separation is 3000 - 10000 r / min, and the time is 10 - 60 min.

[0023] Furthermore, in step S4, the temperature of the vacuum drying is 60 - 100 °C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. A highly thermally conductive biaxially stretched polyamide film provided by the present invention incorporates a thermally conductive material added with nano-thin two-dimensional boron nitride, which can effectively improve the thermal conductivity and mechanical properties of the film. By adding branched polyethyleneimine-block-polyethylene glycol and 4,4'-methylenebis(cyclohexyl isocyanate), due to the high degree of branching and the presence of a large number of -NH2 and NCO bonds, the compatibility between boron nitride and polyamide 6 is good, and at the same time, the exfoliation efficiency of boron nitride is improved, forming an ultra-thin two-dimensional structure, which can greatly enhance the thermal conductivity of the film material.

[0026] 2. A highly thermally conductive biaxially stretched polyamide film provided by the present invention has improved the preparation method of nano-thin two-dimensional boron nitride. After being treated by the preparation method of the present invention, the nano-thin two-dimensional boron nitride forms a material with a single-layer or two-layer structure, and its thickness can be basically ignored. Therefore, the addition amount of boron nitride can be reduced, and the enhancement of mechanical properties can be achieved. Moreover, a large number of polar groups are introduced during the preparation of nano-thin two-dimensional boron nitride, so its compatibility with polyamide 6 can be improved. At the same time, excellent compatibility can also enable it to better spread into a thin flake single-layer state in the material to a certain extent, thus achieving a full-channel heat conduction path inside the material and greatly enhancing the thermal conductivity of the material. Instead of the island structure where it agglomerates inside the material itself and separates from the polymer component. In addition, the nano-thin two-dimensional boron nitride provided by the present invention has fewer internal defect structures, and the existence of defect structures such as vacancies or incomplete edges will increase phonon scattering and reduce the thermal conductivity. Furthermore, through the nano-thin two-dimensional boron nitride formed in the present invention, not only a single-layer or few-layer structure is formed, but also the sheet diameter on its two-dimensional scale is larger. The larger the sheet diameter, the longer the phonon mean free path, and the heat of this material mainly depends on the transfer of phonons. Therefore, this structure further promotes a significant improvement in thermal conductivity. Ordinary single-layer or few-layer nano-thin two-dimensional boron nitride is anisotropic. However, during the preparation process of the biaxially stretched polyamide film of the present invention, due to its unique stretching process conditions, under the action of tensile stress, the vertical arrangement of the nano-thin two-dimensional boron nitride of the present invention will increase, further forming a highly ordered dense structure, thereby effectively reducing the interfacial thermal resistance and greatly enhancing the thermal conductivity of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a highly thermally conductive biaxially stretched polyamide film provided by the present invention.

[0028] In the figure, 10, lower surface layer; 20, intermediate layer; 30, upper surface layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following combines preferred embodiments and refers to the attachedFigure 1 , to further illustrate the present invention. In the scope disclosed in the present invention, the endpoints and any values of the scope are not limited to the exact scope or value. These scopes or values should be understood to include values close to these scopes or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. The materials, reagents, etc. used in the following examples can be obtained from commercial sources without special instructions. The experimental methods in the following examples are conventional methods without special instructions.

[0030] In the present invention, the thermally conductive polyamide 6 is purchased from the market.

[0031] Example 1

[0032] This example provides a highly thermally conductive biaxially stretched polyamide film. As Figure 1 shown, the film has a three-layer structure, which is the upper surface layer 30, the middle layer 20, and the lower surface layer 10 from top to bottom in sequence;

[0033] The upper surface layer 30 is composed of the following raw materials in parts by weight: 4 parts of anti-sticking masterbatch, 10 parts of thermally conductive material, 30 parts of thermally conductive polyamide 6, and 56 parts of polyamide 6;

[0034] The middle layer 20 is composed of the following raw materials in parts by weight: 12 parts of thermally conductive material, 30 parts of thermally conductive polyamide 6, and 58 parts of polyamide 6;

[0035] The lower surface layer 10 is composed of the following raw materials in parts by weight: 4 parts of anti-sticking masterbatch, 10 parts of thermally conductive material, 30 parts of thermally conductive polyamide 6, and 56 parts of polyamide 6;

[0036] Among them, the thermally conductive material is composed of the following raw materials in parts by weight: 10 parts of nano-ultrathin two-dimensional boron nitride, 4 parts of branched polyethyleneimine-block-polyethylene glycol, 5 parts of 4,4'-methylenebis(cyclohexyl isocyanate), and 81 parts of polyamide 6.

[0037] In this example, the preparation process of nano-ultrathin two-dimensional boron nitride in the thermally conductive material is as follows:

[0038] S1: Ball-mill 10 parts of boron nitride powder;

[0039] In this example, the rotation speed of the ball-milling is 600 r / min, and the ball-milling time is 5 h.

[0040] S2: While stirring, add 90 parts of dimethylformamide solution to the ball-milled boron nitride obtained in step S1, and obtain a uniform suspension after ultrasonic dispersion;

[0041] In this embodiment, the stirring speed is 120 r / min, and the time of ultrasonic dispersion is 300 min.

[0042] S3: Add 10 parts of cetyltrimethylammonium bromide to the suspension obtained in step S2, stir evenly, and then react at 3 MPa and 140 °C for 25 h. After the reaction is completed, cool to room temperature, and obtain a mixed solution after ultrasonic treatment and high-speed stirring;

[0043] In this embodiment, the ultrasonic power of the ultrasonic treatment is 400 W, the time is 6 h, the speed of high-speed stirring is 3000 r / min, and the time is 4 h.

[0044] S4: Centrifuge the mixed solution obtained in step S3, take the upper-layer dispersion, wash it 4 times with deionized water, and perform vacuum drying to obtain the nano-thin two-dimensional boron nitride.

[0045] In this embodiment, the speed of the centrifugation is 7000 r / min, the time is 30 min, and the temperature of the vacuum drying is 80 °C.

[0046] Example 2

[0047] This embodiment provides a highly thermally conductive biaxially stretched polyamide film. The film has a three-layer structure, which is an upper surface layer, a middle layer, and a lower surface layer from top to bottom in sequence;

[0048] The upper surface layer is composed of the following raw materials in parts by weight: 2 parts of anti-adhesive masterbatch, 6 parts of thermal conductive material, 8 parts of thermally conductive polyamide 6, and 84 parts of polyamide 6;

[0049] The middle layer is composed of the following raw materials in parts by weight: 6 parts of thermal conductive material, 6 parts of thermally conductive polyamide 6, and 88 parts of polyamide 6;

[0050] The lower surface layer is composed of the following raw materials in parts by weight: 2 parts of anti-adhesive masterbatch, 6 parts of thermal conductive material, 8 parts of thermally conductive polyamide 6, and 84 parts of polyamide 6;

[0051] Among them, the thermal conductive material is composed of the following raw materials in parts by weight: 2 parts of nano-thin two-dimensional boron nitride, 1 part of branched polyethyleneimine-block-polyethylene glycol, 1 part of 4,4'-methylenebis(cyclohexyl isocyanate), and 96 parts of polyamide 6.

[0052] In this embodiment, the preparation process of the nano-thin two-dimensional boron nitride in the thermal conductive material is as follows:

[0053] S1: Ball-mill 2 parts of boron nitride powder;

[0054] In this embodiment, the rotation speed of the ball-milling is 350 r / min, and the ball-milling time is 2 h.

[0055] S2: While stirring, add 98 parts of dimethylformamide solution to the ball-milled boron nitride obtained in step S1, and obtain a uniform suspension after ultrasonic dispersion;

[0056] In this embodiment, the stirring speed is 200 r / min, and the time of ultrasonic dispersion is 40 min.

[0057] S3: Add 2 parts of cetyltrimethylammonium bromide to the suspension obtained in step S2, stir evenly, then react at 1.8 MPa and 110 °C for 6 h. After the reaction is completed, cool to room temperature, and obtain a mixed solution after ultrasonic treatment and high-speed stirring;

[0058] In this embodiment, the ultrasonic power of the ultrasonic treatment is 150 W, the time is 3 h, the speed of high-speed stirring is 1500 r / min, and the time is 1.5 h.

[0059] S4: Centrifuge the mixed solution obtained in step S3, take the upper-layer dispersion liquid, wash it 3 times with deionized water, and perform vacuum drying to obtain the nano-thin two-dimensional boron nitride.

[0060] In this embodiment, the speed of centrifugation is 3500 r / min, the time is 15 min, and the temperature of vacuum drying is 65 °C.

[0061] Example 3

[0062] This embodiment provides a high thermal conductivity biaxially stretched polyamide film, and the film is a three-layer structure, which is successively an upper surface layer, a middle layer and a lower surface layer from top to bottom;

[0063] The upper surface layer is composed of the following raw materials in parts by weight: 7 parts of anti-sticking masterbatch, 18 parts of thermal conductive material, 48 parts of thermally conductive polyamide 6, and 27 parts of polyamide 6;

[0064] The middle layer is composed of the following raw materials in parts by weight: 22 parts of thermal conductive material, 58 parts of thermally conductive polyamide 6, and 20 parts of polyamide 6;

[0065] The lower surface layer is composed of the following raw materials in parts by weight: 7 parts of anti-sticking masterbatch, 18 parts of thermal conductive material, 48 parts of thermally conductive polyamide 6, and 20 parts of polyamide 6;

[0066] Among them, the thermal conductive material is composed of the following raw materials in parts by weight: 14 parts of nano-thin two-dimensional boron nitride, 7 parts of branched polyethyleneimine-block-polyethylene glycol, 9 parts of 4,4'-methylenebis(cyclohexyl isocyanate), and 70 parts of polyamide 6.

[0067] In this embodiment, the preparation process of nano-thin two-dimensional boron nitride in the thermal conductive material is as follows:

[0068] S1: Ball-mill 18 parts of boron nitride powder;

[0069] In this embodiment, the rotation speed of the ball milling is 900 r / min, and the ball milling time is 9 h.

[0070] S2: While stirring, 82 parts of dimethylformamide solution are added to the ball-milled boron nitride obtained in step S1, and a uniform suspension is obtained after ultrasonic dispersion.

[0071] In this embodiment, the stirring speed is 500 r / min, and the ultrasonic dispersion time is 160 min.

[0072] S3: 13 parts of cetyltrimethylammonium bromide are added to the suspension obtained in step S2 and stirred evenly, and then the reaction is carried out at 5 MPa and 190 °C for 50 h. After the reaction is completed, it is cooled to room temperature, and a mixed solution is obtained after ultrasonic treatment and high-speed stirring.

[0073] In this embodiment, the ultrasonic power of the ultrasonic treatment is 600 W, the time is 12 h, the high-speed stirring speed is 5000 r / min, and the time is 5.5 h.

[0074] S4: The mixed solution obtained in step S3 is centrifuged, the upper dispersion liquid is taken, washed 6 times with deionized water, and vacuum dried to obtain the nano-thin two-dimensional boron nitride.

[0075] In this embodiment, the centrifugation speed is 9000 r / min, the time is 55 min, and the vacuum drying temperature is 95 °C.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that the raw material composition of the film is different.

[0078] The film of this comparative example has a three-layer structure, which is an upper surface layer, a middle layer and a lower surface layer from top to bottom in sequence.

[0079] The upper surface layer is composed of the following raw materials in parts by weight: 4 parts of anti-adhesive masterbatch and 96 parts of polyamide 6.

[0080] The middle layer is composed of the following raw materials in parts by weight: 100 parts of polyamide 6.

[0081] The lower surface layer is composed of the following raw materials in parts by weight: 4 parts of anti-adhesive masterbatch and 96 parts of polyamide 6.

[0082] Comparative Example 2

[0083] The difference from Example 1 is that:

[0084] The thermal conductive material of this comparative example is composed of the following raw materials in parts by weight: 10 parts of nano-talc powder, 4 parts of branched polyethyleneimine-block-polyethylene glycol, 5 parts of 4,4'-methylenebis(cyclohexyl isocyanate), and 81 parts of polyamide 6.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that: the raw materials of the film in this comparative example do not contain thermal conductive materials;

[0087] The film of this comparative example has a three-layer structure, which is the upper surface layer, the middle layer and the lower surface layer from top to bottom in sequence;

[0088] The upper surface layer is composed of the following raw materials in parts by weight: 4 parts of anti-sticking masterbatch, 30 parts of thermally conductive polyamide 6, and 66 parts of polyamide 6;

[0089] The middle layer is composed of the following raw materials in parts by weight: 30 parts of thermally conductive polyamide 6 and 70 parts of polyamide 6;

[0090] The lower surface layer is composed of the following raw materials in parts by weight: 4 parts of anti-sticking masterbatch, 30 parts of thermally conductive polyamide 6, and 66 parts of polyamide 6.

[0091] Evaluation of implementation effect

[0092] The following is a specific test on the films prepared in Examples 1-3 and Comparative Examples 1-3 to further illustrate the excellent effects achieved by the present invention:

[0093] Tensile strength performance test: The test is carried out according to the standard requirements of GB / T 1040.3 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets".

[0094] Thermal conductivity test: The test is carried out according to the standard requirements of GB / T 10297-2015 "Determination of thermal conductivity of non-metallic solid materials - Hot wire method".

[0095] The test results are shown in the following table

[0096] Table 1 Statistical table of test results

[0097]

[0098] It can be seen from the above table that the high thermal conductivity biaxially oriented polyamide film prepared by the present invention has excellent thermal conductivity and excellent mechanical properties. It shows that by adding the thermal conductive material containing nano-thin two-dimensional boron nitride, the thermal conductivity and mechanical properties of the film are effectively improved.

[0099] It can be seen from the experimental data of Example 1 and Comparative Example 1 that the film prepared without the thermal conductive material of the present invention not only has poor thermal conductivity of the film, but also has poor mechanical properties.

[0100] It can be seen from the experimental data of Example 1 and Comparative Example 2 that replacing the nano-thin two-dimensional boron nitride in the thermal conductive material with ordinary inorganic powder has limited improvement in thermal conductivity. However, its nano-structure plays a certain role in improving the mechanical properties, but the effect is also limited.

[0101] It can be seen from the experimental data of Example 1 and Comparative Example 3 that in the absence of a thermal conductive material, due to the presence of thermally conductive polyamide 6, both its thermal conductivity and mechanical properties have been greatly improved, but it cannot reach the effect of Example 1. The thermal conductive material and thermally conductive polyamide 6 do not exist in isolation, and there is a synergistic effect between them.

[0102] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention.

Claims

1. A high thermal conductivity biaxially oriented polyamide film, characterized in that, The film has a three-layer structure, which is, from top to bottom, an upper surface layer, a middle layer, and a lower surface layer in sequence; The upper surface layer is composed of the following raw materials in parts by weight: 1 - 8 parts of anti-sticking masterbatch, 5 - 20 parts of heat-conducting material, 5 - 50 parts of heat-conducting polyamide 6, and 22 - 89 parts of polyamide 6; The middle layer is composed of the following raw materials in parts by weight: 5 - 25 parts of heat-conducting material, 5 - 60 parts of heat-conducting polyamide 6, and 15 - 90 parts of polyamide 6; The lower surface layer is composed of the following raw materials in parts by weight: 1 - 8 parts of anti-sticking masterbatch, 5 - 20 parts of heat-conducting material, 5 - 50 parts of heat-conducting polyamide 6, and 22 - 89 parts of polyamide 6; Among them, the heat-conducting material is composed of the following raw materials in parts by weight: 0.5 - 15 parts of nano-thin two-dimensional boron nitride, 0.5 - 8 parts of branched polyethyleneimine-block-polyethylene glycol, 0.1 - 10 parts of 4,4'-methylenebis(cyclohexyl isocyanate), and 67 - 98.9 parts of polyamide 6.

2. The high thermal conductivity biaxially oriented polyamide film according to claim 1, characterized in that, The preparation process of nano-thin two-dimensional boron nitride in the heat-conducting material is as follows: S1: Ball-mill 1 - 20 parts of boron nitride powder; S2: While stirring, add 80 - 99 parts of dimethylformamide solution to the ball-milled boron nitride obtained in step S1, and obtain a uniform suspension after ultrasonic dispersion; S3: Add 1 - 15 parts of cetyltrimethylammonium bromide to the suspension obtained in step S2, stir evenly, and then react at 1.5 - 5 MPa and 100 - 190 °C for 5 - 50 h. After the reaction ends, cool to room temperature, and obtain a mixed solution after ultrasonic treatment and high-speed stirring; S4: Centrifuge the mixed solution obtained in step S3, take the upper dispersion liquid, wash it 3 - 6 times with deionized water, and perform vacuum drying to obtain the nano-thin two-dimensional boron nitride.

3. The high thermal conductivity biaxially oriented polyamide film according to claim 2, wherein In step S1, the rotation speed of the ball-milling is 300 - 1000 r / min, and the ball-milling time is 1 - 10 h.

4. The high thermal conductivity biaxially oriented polyamide film according to claim 2, wherein, In step S2, the stirring speed is 100 - 500 r / min, and the ultrasonic dispersion time is 30 - 180 min.

5. The high thermal conductivity biaxially oriented polyamide film according to claim 2, wherein, In step S3, the ultrasonic power of the ultrasonic treatment is 100 - 600 W, and the time is 2 - 12 h.

6. The high thermal conductivity biaxially oriented polyamide film according to claim 2, wherein, In step S3, the speed of the high-speed stirring is 1000 - 5000 r / min, and the time is 1 - 6 h.

7. The high thermal conductivity biaxially oriented polyamide film according to claim 2, wherein, In step S4, the speed of the centrifugation is 3000 - 10000 r / min, and the time is 10 - 60 min.

8. The high thermal conductivity biaxially oriented polyamide film according to claim 2, wherein, In step S4, the temperature of the vacuum drying is 60 - 100 °C.

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