Heat-conducting nylon plastic and preparation method thereof

Abstract

The invention relates to the technical field of nylon plastics, in particular to a heat-conducting nylon plastic and a preparation method thereof. The heat-conducting nylon plastic provided by the invention is prepared from the following substances in parts by mass: 70 to 85 parts of a nylon matrix, 15 to 25 parts of flaky boron nitride, 10 to 15 parts of spherical aluminum nitride, 2 to 3 parts of aluminum oxide, 5 to 10 parts of silicon carbide whiskers, 3 to 5 parts of cellulose nanocrystals, 0 to 0.5 part of 2-benzimidazolone, 0.2 to 0.8 part of an anti-hydrolysis agent and 0.2 to 0.3 part of an antioxidant. The preparation method of the heat-conducting nylon plastic comprises the following steps: S21, mixing; s22, carrying out melt blending; and S23, molding to obtain the heat-conducting nylon plastic. The prepared heat-conducting nylon plastic is high in bending strength and impact strength, the heat conductivity coefficient is not lower than 6.8 W / (m.K), and the mechanical property is basically equivalent to that of nylon PA66.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nylon plastic, in particular to a heat-conducting nylon plastic and a preparation method thereof. BACKGROUND

[0002] As a kind of functional polymer material, heat-conducting nylon has been widely used in LED lighting, automobile, electronic and electrical fields in recent years. It is a kind of polymer composite formed by filling heat-conducting fillers such as aluminum nitride, silicon carbide and aluminum oxide into nylon. This kind of material combines the simplicity of plastic forming with excellent thermal conductivity, providing more design freedom for designers, and the weight of the product is only half of that of aluminum products. With the continuous improvement of the power density of electronic equipment and the rapid development of LED lighting technology, efficient heat dissipation has become a key factor in product design, and heat-conducting nylon is one of the ideal materials to meet this demand.

[0003] Compared with traditional metal heat dissipation materials, heat-conducting nylon has lower density (37%-50% lower than aluminum) and more excellent design freedom. The thermal conductivity of heat-conducting plastic depends on the interaction between polymer and heat-conducting filler. Different types of fillers have different heat-conducting mechanisms: (1) metal fillers such as copper powder, aluminum powder and iron powder, which conduct heat mainly by electron movement, and the process of electron movement is accompanied by heat transfer. (2) Non-metallic fillers such as aluminum oxide, boron nitride and silicon carbide, which conduct heat mainly by phonon conduction, and the heat energy diffusion rate mainly depends on the vibration of adjacent atoms or bonding groups. When the filling amount of heat-conducting filler is very small, the heat-conducting fillers cannot form real contact and interaction, which has little effect on the improvement of the thermal conductivity of the polymer material. Only when the filling of heat-conducting fillers in the polymer matrix reaches a certain critical value, there is a real interaction between the heat-conducting fillers, and a network or chain-like morphology, heat-conducting network chain, is formed in the system. When the orientation of the heat-conducting network chain is consistent with the direction of heat flow, the thermal conductivity improves quickly.

[0004] However, heat-conducting nylon still has the following shortcomings: (1) The thermal conductivity is still limited, and compared with traditional metal materials, the thermal conductivity of heat-conducting nylon is still low. The thermal conductivity of aluminum is 100-200 W / (m·K), while the thermal conductivity of heat-conducting nylon is 0.8-15 W / (m·K). (2) High filler content affects mechanical properties. When the filler content increases to a certain critical value, effective heat-conducting network chain can be formed. However, when the filler is too much, the mechanical properties of the composite material will be greatly affected. (3) Cost problem. Although it has cost advantage compared with metal, the high thermal conductivity filler is expensive, which also limits the popularization and application of heat dissipation plastic. (4) Immature technology, high filling rate material forming processing difficulty and other problems limit the popularization and application of heat-conducting plastic.

[0005] CN109354868 B provides a kind of graphene modified flame-retardant heat-conducting nylon plastic, comprising the following mass fraction of ingredients: high flowability nylon 6 is 44~72%; Negative ion powder 5~10%; Sulphonated graphene 5~10%; Spherical ceramic powder 1~3%; Polyamide elastomer 3~6%; Flame retardant 10~20%; Flame retardant synergist 3~5%; Processing aid 1~2%.Its preparation method is also disclosed.The prepared graphene modified flame-retardant heat-conducting nylon plastic has high thermal conductivity and flame-retardant performance, with thermal conductivity coefficient reaching more than 5W / (m·K), and flame-retardant level being V-0.

[0006] Future research will focus on improving the comprehensive performance of heat-conducting nylon, including thermal conductivity, mechanical properties and processing performance.By developing new heat-conducting fillers, optimizing filler shape and improving the bonding characteristics of filler and matrix material interface, the performance of heat-conducting nylon will be further improved. SUMMARY

[0007] The application provides a kind of heat-conducting nylon plastic, which is composed of the following mass components:

[0008] Nylon matrix 70~85 parts;

[0009] Flaky boron nitride 15~25 parts;

[0010] Spherical aluminum nitride 10~15 parts;

[0011] Alumina 2~3 parts;

[0012] Silicon carbide whisker 5~10 parts;

[0013] Cellulose nanocrystal 3~5 parts;

[0014] 2-benzimidazolone 0~0.5 parts;

[0015] Anti-hydrolysis agent 0.2-0.8 parts;

[0016] Antioxidant 0.2~0.3 parts.

[0017] As a two-dimensional dominant thermal filler, flaky boron nitride has a layered structure similar to graphite, with a high in-plane thermal conductivity, and is an excellent electrical insulator. Under the action of shear force, flaky boron nitride is oriented and arranged in the nylon matrix to form a "fast lane" in the in-plane direction, greatly improving the material in the parallel direction to the orientation direction, which is the core of building the dominant thermal network. Spherical aluminum nitride as a three-dimensional lattice thermal node and filler. Spherical aluminum nitride has a high thermal conductivity, and its spherical particles can effectively fill the voids formed by the stacking of flaky boron nitride, connect the separated boron nitride layers, reduce phonon scattering, and reduce the interfacial thermal resistance. The spherical particles are more likely to form point contacts in three-dimensional space, complementing the two-dimensional planar network of flaky boron nitride, reducing the thermal anisotropy. The high aspect ratio of silicon carbide whiskers enables it to penetrate into the thermal network formed by flaky boron nitride and aluminum nitride like a "steel needle", establishing more "thermal bridges" between fillers, significantly enhancing the connectivity and stability of the thermal network. While improving thermal conductivity, silicon carbide whiskers can greatly compensate for the loss of mechanical properties, especially flexural strength and modulus, due to the addition of thermal fillers, preventing material embrittlement. The "three-dimensional hybrid thermal network" composed of flaky boron nitride, spherical aluminum nitride and one-dimensional silicon carbide whiskers, the synergy of boron nitride and aluminum nitride, flaky boron nitride provides a high thermal conduction path in the two-dimensional plane, while spherical aluminum nitride acts as a node to fill the voids and connect different boron nitride planes, expanding the two-dimensional network to a three-dimensional network. The synergy of silicon carbide whiskers, silicon carbide whiskers as "super connecting lines", further strengthens the connection between boron nitride and aluminum nitride, stabilizes the entire thermal skeleton, and achieves mechanical enhancement. The synergistic effect of the three through excellent interface modification, quantum thermal vibrations can be more efficiently transmitted between filler-filler and filler-matrix, fully exploiting the thermal conductivity potential of each component. 2-benzimidazolone as an interfacial phonon coupling agent, its unique molecular structure can form a hydrogen bond with the amide bond of the nylon matrix at one end, and produce π-π stacking or van der Waals force with the thermal filler at the other end, forming a "phonon bridge" to reduce the interfacial thermal resistance.

[0018] Further, the boron nitride is modified flaky boron nitride, and a preparation method thereof is as follows: the flaky boron nitride is dispersed in ethanol with a mass of 3 times that of the flaky boron nitride, 0.1 times the mass of the flaky boron nitride of γ-aminopropyl triethoxysilane is added, and the mixture is reacted at 80 ℃ for 2 hours, then 0.3 times the mass of the flaky boron nitride of dopamine hydrochloride and a tris(hydroxymethyl) aminomethane aqueous solution is added, and the mixture is deposited at room temperature for 12 hours, to obtain the modified boron nitride, wherein the concentration of the dopamine hydrochloride and the tris(hydroxymethyl) aminomethane in the dopamine hydrochloride and the tris(hydroxymethyl) aminomethane aqueous solution is 0.05 mol / L. The flaky boron nitride coated by the γ-aminopropyl triethoxysilane and the polydopamine constructs a main path of phonon conduction in the plane direction, the γ-aminopropyl triethoxysilane enhances the interface bonding, the polydopamine inhibits the agglomeration of the filler, meanwhile, the alkoxyl group in the γ-aminopropyl triethoxysilane can react with the hydroxyl group on the surface of other components to form a chemical bond, and the other end of the amino group can be combined with the nylon matrix, the “flexible interface layer” effectively reduces the interface thermal resistance and promotes the stress transfer, thereby simultaneously improving the thermal conductivity and the mechanical properties.

[0019] Further, the flaky boron nitride is graphene modified flaky boron nitride, and a preparation method thereof is as follows: the flaky boron nitride is placed in a reaction furnace, CH4 / H2 / Ar mixed gas is introduced, and the mixture is reacted at 750 ℃ for 3 hours to vertically grow graphene on the surface of the flaky boron nitride, wherein the volume ratio of the CH4 / H2 / Ar mixed gas is 8:1:1. The flaky boron nitride forms a horizontal heat conduction path, and the graphene forms a vertical heat conduction path, to construct a “phonon-electron” bimodal heat transfer network, and the thermal conductivity is obviously improved.

[0020] Further, the aluminum oxide is composed of α-Al2O3 with a particle size D50=5 μm and γ-Al2O3 with a particle size D50=0.8 μm at a mass ratio of 3:1. The spherical particles fill the gaps between the boron nitride to form a three-dimensional heat conduction network, and the aluminum oxide fillers with different crystal phases and particle sizes are matched to help optimize the packing density of the fillers, possibly reduce phonon scattering, and thereby improve the thermal conductivity of the composite material.

[0021] Further, the anti-hydrolysis agent is polycarbodiimide. The anti-hydrolysis agent is used to inhibit the hydrolytic degradation of the nylon matrix and the flaky boron nitride at high temperature and high humidity, the carbodiimide group in the molecule can preferentially react with the carboxyl group generated by hydrolysis to block the chain reaction of the broken nylon molecular chain, and at the same time, the flaky boron nitride is protected to ensure the long-term stability of the material.

[0022] Further, the antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite at a mass ratio of 1:1. The compounded antioxidant is used to prevent thermal oxidative degradation of the material during processing and use.

[0023] Further, the nylon matrix is PA66. The nylon matrix as the continuous phase of the composite material provides the basic mechanical framework and processing performance, preferably PA66 or PA6T. PA66 has a higher melting point and good mechanical strength, and is an ideal choice for general engineering plastics. PA6T has a higher heat distortion temperature and better solder resistance, and is suitable for electronic components in surface mount technology process.

[0024] Further, the cellulose nanocrystals are surface-mineralized cellulose nanocrystals, and the preparation method comprises the following steps:

[0025] S11. Pretreatment: 5 parts of cellulose nanocrystals are dispersed in 500 parts of deionized water, and treated by a high-pressure homogenizer to obtain a transparent cellulose nanocrystal gel;

[0026] S12. Mineralization reaction: the cellulose nanocrystal gel obtained in step S11 is placed in a reaction kettle, 100 parts of 0.5 mol / L CaCl2 solution is added, and the calcium ions are fully adsorbed to the surface of the cellulose nanocrystals under slow stirring at 60°C for 2 hours;

[0027] S13. Precipitation reaction: 100 parts of 0.5 mol / L sodium carbonate solution is added dropwise, and the dropwise adding speed is controlled to generate nanometer calcium carbonate crystals in situ on the surface of the cellulose nanocrystals;

[0028] S14. Post-treatment: after the reaction is completed, filtration is performed, and the obtained product is washed with deionized water until it is neutral, and finally freeze-dried to obtain fluffy white powder of surface-mineralized cellulose nanocrystals. The silicon carbide whiskers and the surface-mineralized cellulose nanocrystals form a multi-level fiber network from nanometers to microns, prevent the destruction of the heat conduction network under high filling, and endow the composite material with excellent processing performance and impact toughness.

[0029] The preparation method of the heat-conducting nylon plastic described above comprises the following steps:

[0030] S21. Mixing: the components in the formula are mixed uniformly according to the proportions;

[0031] S22. Melt blending: the mixed materials are put into a double-screw extruder for melt extrusion and granulation;

[0032] S23. Molding: the obtained granules are dried, and then injection molded or extruded to obtain the heat-conducting nylon plastic, and the extrusion processing temperature is 250-285°C.

[0033] The heat-conducting nylon plastic described above can be applied in the preparation of electronic device heat dissipation shells, LED lamp holders, power semiconductor insulation heat dissipation substrates, or automobile engine peripheral heat-resistant components.

[0034] Compared with the prior art, the present application has the following advantages:

[0035] 1. Excellent thermal conductivity: thermal conductivity coefficient can reach 6.8-7.5 W / ((m·K)), much higher than ordinary nylon, and small anisotropy.

[0036] 2. Balanced mechanical properties: while obtaining high thermal conductivity, high bending strength and impact strength are maintained.

[0037] 3. Good processing performance: filler dispersion is uniform, melt flowability is suitable, and injection molding and extrusion molding are easy.

[0038] 4. Good thermal stability and hydrolysis resistance: by adding anti-hydrolysis agent and optimizing process, the industry problem of easy hydrolysis of aluminum nitride is solved. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the application, not all.

[0040] Example 1

[0041] A thermally conductive nylon plastic is composed of the following mass components:

[0042] Nylon matrix 75 parts;

[0043] Flaky boron nitride 20 parts;

[0044] Spherical aluminum nitride 12 parts;

[0045] Alumina 2 parts;

[0046] Silicon carbide whisker 6 parts;

[0047] Surface mineralized cellulose nanocrystal 4 parts;

[0048] Anti-hydrolysis agent 0.4 parts;

[0049] Antioxidant 0.2 parts.

[0050] The anti-hydrolysis agent is polycarbodiimide.

[0051] The antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1.

[0052] The nylon matrix is PA66.

[0053] The preparation method of the thermally conductive nylon plastic comprises the following steps:

[0054] S21. Mixing: mix the components in the formula in proportion;

[0055] S22. Melt blending: the mixed material is put into a twin-screw extruder for melt extrusion and granulation;

[0056] S23. Molding: the obtained granules are dried, and then injection molded or extruded to obtain the heat-conducting nylon plastic, and the extrusion processing temperature is 268-272℃.

[0057] The heat-conducting nylon plastic can be applied in the preparation of electronic device heat dissipation shell, LED lamp holder, power semiconductor insulation heat dissipation substrate, or automobile engine peripheral heat-resistant components.

[0058] Example 2

[0059] A heat-conducting nylon plastic is composed of the following mass components:

[0060] Nylon matrix 75 parts;

[0061] Flaky boron nitride 20 parts;

[0062] Spherical aluminum nitride 12 parts;

[0063] Alumina 2 parts;

[0064] Silicon carbide whisker 6 parts;

[0065] Surface mineralized cellulose nanocrystal 4 parts;

[0066] 2-benzimidazolone 0.3 parts;

[0067] Anti-hydrolysis agent 0.4 parts;

[0068] Antioxidant 0.2 parts.

[0069] The anti-hydrolysis agent is polycarbodiimide.

[0070] The antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1.

[0071] The nylon matrix is PA66.

[0072] The preparation method of the heat-conducting nylon plastic comprises the following steps:

[0073] S21. Mixing: the components in the formula are mixed uniformly in proportion;

[0074] S22. Melt blending: the mixed material is put into a twin-screw extruder for melt extrusion and granulation;

[0075] S23. Molding: the obtained granules are dried, and then injection molded or extruded to obtain the heat-conducting nylon plastic, and the extrusion processing temperature is 268-272℃.

[0076] The heat-conducting nylon plastic can be applied in the preparation of electronic device heat dissipation shell, LED lamp holder, power semiconductor insulation heat dissipation substrate or automobile engine peripheral heat-resistant components.

[0077] Embodiment 3

[0078] A heat-conducting nylon plastic is composed of the following mass components:

[0079] Nylon matrix 75 parts;

[0080] Flaky boron nitride 20 parts;

[0081] Spherical aluminum nitride 12 parts;

[0082] Alumina 2 parts;

[0083] Silicon carbide whisker 6 parts;

[0084] Surface mineralized cellulose nanocrystal 4 parts;

[0085] Anti-hydrolysis agent 0.4 parts;

[0086] Antioxidant 0.2 parts.

[0087] The anti-hydrolysis agent is polycarbodiimide.

[0088] The antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1.

[0089] The nylon matrix is PA66.

[0090] The flaky boron nitride is modified flaky boron nitride, and the preparation method is as follows: dispersing flaky boron nitride in ethanol with a mass of 3 times that of the flaky boron nitride, adding γ-aminopropyltriethoxysilane with a mass of 0.1 times that of the flaky boron nitride, reacting at 80℃ for 2h, then adding dopamine hydrochloride and tris(hydroxymethyl) aminomethane aqueous solution with a mass of 0.3 times that of the flaky boron nitride, depositing at room temperature for 12h to obtain modified flaky boron nitride, and the concentration of dopamine hydrochloride and tris(hydroxymethyl) aminomethane in the dopamine hydrochloride and tris(hydroxymethyl) aminomethane aqueous solution is 0.05mol / L.

[0091] The preparation method of the heat-conducting nylon plastic comprises the following steps:

[0092] S21. Mixing: uniformly mixing the components in the formula according to the proportion;

[0093] S22. Melt blending: putting the mixed material into a double screw extruder for melt extrusion and granulation;

[0094] S23. Molding: After drying the obtained granules, injection molding or extrusion molding is performed to obtain thermally conductive nylon plastic, wherein the extrusion processing temperature is 268~272℃.

[0095] The thermally conductive nylon plastic can be used in the manufacture of heat dissipation shells for electronic devices, LED lamp holders, insulating heat dissipation substrates for power semiconductors, or heat-resistant components around automotive engines.

[0096] Example 4

[0097] A thermally conductive nylon plastic, composed of the following components by mass:

[0098] 75 parts of nylon matrix;

[0099] 20 parts of sheet-like boron nitride;

[0100] 12 parts of spherical aluminum nitride;

[0101] 2 parts aluminum oxide;

[0102] Six parts of silicon carbide whiskers;

[0103] Four portions of surface-mineralized cellulose nanocrystals;

[0104] 0.4 parts of anti-hydrolysis agent;

[0105] Antioxidant 0.2 parts.

[0106] The anti-hydrolysis agent is polycarbodiimide.

[0107] The antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1.

[0108] The nylon matrix is ​​PA66.

[0109] The sheet-like boron nitride is graphene-modified sheet-like boron nitride, and its preparation method is as follows: place the sheet-like boron nitride in a reaction furnace, introduce a CH4 / H2 / Ar mixed gas, react at 750℃ for 3 hours, and vertically grow graphene on the surface of the sheet-like boron nitride. The volume ratio of the CH4 / H2 / Ar mixed gas is 8:1:1.

[0110] The method for preparing the thermally conductive nylon plastic includes the following steps:

[0111] S21. Mixing: Mix the components in the formula evenly according to the proportions;

[0112] S22. Melt blending: The mixed materials are fed into a twin-screw extruder for melt extrusion and granulation;

[0113] S23. Molding: After drying the obtained granules, injection molding or extrusion molding is performed to obtain thermally conductive nylon plastic, wherein the extrusion processing temperature is 268~272℃.

[0114] The thermally conductive nylon plastic can be used in the manufacture of heat dissipation shells for electronic devices, LED lamp holders, insulating heat dissipation substrates for power semiconductors, or heat-resistant components around automotive engines.

[0115] Example 5

[0116] A thermally conductive nylon plastic, composed of the following components by mass:

[0117] 75 parts of nylon matrix;

[0118] 20 parts of sheet-like boron nitride;

[0119] 12 parts of spherical aluminum nitride;

[0120] 2 parts aluminum oxide;

[0121] Six parts of silicon carbide whiskers;

[0122] Four portions of surface-mineralized cellulose nanocrystals;

[0123] 0.4 parts of anti-hydrolysis agent;

[0124] Antioxidant 0.2 parts.

[0125] The anti-hydrolysis agent is polycarbodiimide.

[0126] The antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1.

[0127] The nylon matrix is ​​PA66.

[0128] The alumina is composed of α-Al2O3 with a particle size of D50=5μm and γ-Al2O3 with a particle size of D50=0.8μm in a mass ratio of 3:1.

[0129] The method for preparing the thermally conductive nylon plastic includes the following steps:

[0130] S21. Mixing: Mix the components in the formula evenly according to the proportions;

[0131] S22. Melt blending: The mixed materials are fed into a twin-screw extruder for melt extrusion and granulation;

[0132] S23. Molding: After drying the obtained granules, injection molding or extrusion molding is performed to obtain thermally conductive nylon plastic, wherein the extrusion processing temperature is 268~272℃.

[0133] The thermally conductive nylon plastic can be used in the manufacture of heat dissipation shells for electronic devices, LED lamp holders, insulating heat dissipation substrates for power semiconductors, or heat-resistant components around automotive engines.

[0134] Comparative Example 1

[0135] Commercially available nylon PA66

[0136] Comparative Example 2

[0137] The only difference is that the plate-shaped boron nitride component in Example 1 is replaced with spherical aluminum nitride; otherwise, it is the same as in Example 1 and will not be repeated.

[0138] Comparative Example 3

[0139] The antioxidant component in Example 1 was removed; all other aspects remained the same as in Example 1, and will not be repeated here.

[0140] The performance test results of the thermally conductive nylon plastics prepared in the embodiments and comparative examples of the present invention are shown in Table 1.

[0141] Table 1

[0142] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thermal conductivity, W / (m-K) 6.8 7.0 7.1 7.4 7.0 0.52 6.6 6.7 Bending strength, MPa 102 102 103 102 102 110 102 101 Tensile strength, MPa Tensile strength, MPa 60 61 63 62 62 65 60 58

[0143] As shown in Table 1 above, commercially available nylon has good mechanical properties but poor thermal conductivity. The thermally conductive nylon plastic prepared by this invention has high flexural strength, high impact strength, and a thermal conductivity of not less than 6.8 W / (m·K), with mechanical properties basically equivalent to nylon PA66. Data from Examples 1, 2, 3, 4, and 5 indicate that 2-benzimidazolone can improve the thermal conductivity and mechanical properties of the product. Modified flake boron nitride has better technical effects, especially graphene-modified flake boron nitride, which significantly improves the thermal conductivity. The product performance is better when the alumina is a mixture of α-Al2O3 and γ-Al2O3. Data from Comparative Example 1 shows that the thermally conductive nylon plastic prepared by this invention has good thermal conductivity with virtually no reduction in mechanical properties. Data from Comparative Example 2 shows that after replacing the flake boron nitride component with spherical aluminum nitride, the synergistic effect disappears, and the product performance slightly decreases. Data from Comparative Example 3 shows that antioxidants can improve product performance.

Claims

1. A thermally conductive nylon plastic, characterized in that, Consists of the following quality components: Nylon matrix 70~85 parts; Flaky boron nitride 15~25 parts; Spherical aluminum nitride 10~15 parts; Alumina 2~3 parts; Silicon carbide whisker 5~10 parts; Cellulose nanocrystal 3~5 parts; 2-benzimidazolone 0~0.5 parts; Anti-hydrolysis agent 0.2-0.8 parts; Antioxidant 0.2~0.3 parts.

2. The thermally conductive nylon plastic of claim 1, wherein, The flaky boron nitride is modified flaky boron nitride, and the preparation method is as follows: dispersing flaky boron nitride in 3 times its mass of ethanol, adding 0.1 times the mass of flaky boron nitride γ-aminopropyl triethoxysilane, reacting at 80℃ for 2h, then adding 0.3 times the mass of flaky boron nitride dopamine hydrochloride and tris(hydroxymethyl) aminomethane aqueous solution, depositing at room temperature for 12h, to obtain modified flaky boron nitride, and the concentration of dopamine hydrochloride and tris(hydroxymethyl) aminomethane in the dopamine hydrochloride and tris(hydroxymethyl) aminomethane aqueous solution is 0.05mol / L.

3. The thermally conductive nylon plastic of claim 1, wherein, The flaky boron nitride is graphene modified flaky boron nitride, and the preparation method is as follows: placing flaky boron nitride in a reaction furnace, introducing CH4 / H2 / Ar mixed gas, reacting at 750℃ for 3h to vertically grow graphene on the surface of flaky boron nitride, and the volume ratio of CH4 / H2 / Ar mixed gas is 8:1:

1.

4. The thermally conductive nylon plastic of claim 1, wherein, The alumina is composed of α-Al2O3 with a particle size D50=5μm and γ-Al2O3 with a particle size D50=0.8μm in a mass ratio of 3:

1.

5. The thermally conductive nylon plastic of claim 1, wherein, The anti-hydrolysis agent is polycarbodiimide.

6. The thermally conductive nylon plastic of claim 1, wherein, The antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:

1.

7. The thermally conductive nylon plastic of claim 1, wherein, The nylon matrix is PA66.

8. The thermally conductive nylon plastic of claim 1, wherein, The cellulose nanocrystal is surface-mineralized cellulose nanocrystal, and the preparation method comprises the following steps: S11. Pretreatment: dispersing 5 parts of cellulose nanocrystal in 500 parts of deionized water, and treating with a high-pressure homogenizer to obtain transparent cellulose nanocrystal gel; S12. Mineralization reaction: placing the cellulose nanocrystal gel obtained in step S11 in a reaction kettle, adding 100 parts of 0.5mol / L CaCl2 solution, slowly stirring at 60℃ for 2h to allow calcium ions to be fully adsorbed to the surface of the cellulose nanocrystal; S13. Precipitation reaction: adding 100 parts of 0.5mol / L sodium carbonate solution dropwise, controlling the dropwise addition rate, and generating nano calcium carbonate crystals in situ on the surface of the cellulose nanocrystal; S14. Post-treatment: after the reaction is completed, suction filtration is performed, and the obtained product is washed with deionized water until it is neutral, and finally freeze-dried to obtain fluffy surface-mineralized cellulose nanocrystal white powder.

9. A method of producing the thermally conductive nylon plastic according to any one of claims 1 to 8, characterized in that, Comprises the following steps: S21. Mixing: uniformly mixing the components in the formula according to the proportions; S22. Melt blending: melt extruding and granulating the mixed material in a twin-screw extruder; S23. Molding: drying the obtained granules, and injection molding or extrusion molding to obtain the heat-conducting nylon plastic, and the extrusion processing temperature is 250~285℃.

10. The thermally conductive nylon plastic of any one of claims 1-8, wherein, The heat-conducting nylon plastic is used in the preparation of electronic device heat dissipation shells, LED lamp holders, power semiconductor insulation heat dissipation substrates, or automobile engine peripheral heat-resistant components.