A thermally conductive composite material, its preparation method and application

Abstract

This invention relates to the field of polymer materials technology, specifically disclosing a thermally conductive composite material, its preparation method, and its applications. The thermally conductive composite material comprises the following raw material components in parts by weight: 80-150 parts polyamide resin; 20-40 parts thermally conductive filler; 5-15 parts flame retardant; 1-5 parts dispersant; and 1-3 parts antioxidant. Research shows that the thermally conductive composite material of this invention not only possesses good thermal conductivity but also good electromagnetic shielding properties, making it of significant application value.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a composite material with thermal conductivity, its preparation method, and its application. Background Technology

[0002] Polyamide resins are typically condensation polymers with a -CONH structure, obtained through the polycondensation of diacids and diamines. Polyamide-66, also known as nylon-66, is a commonly used polyamide resin. Due to its high tensile strength, good abrasion resistance, and electrical insulation properties, it can be used as an engineering plastic and can also be blended or spun purely into various medical and knitted products. However, pure polyamide-66 has a low thermal conductivity and poor thermal performance, which needs further improvement.

[0003] Chinese invention patent CN201410376775.9 discloses a hyperbranched polyamide composite-filled polymer-based thermally conductive plastic and its preparation method. The mass percentages of various raw materials are: matrix resin 20-90%, thermally conductive filler 10-80%, and in addition, by total amount, it also contains toughening agent 0.2-1%, coupling agent 1-3%, antioxidant 0.1-0.5%, and lubricant 0.1-1.5%. The matrix resin is hyperbranched polyamide (HPA) and nylon PA66 in a mass ratio of 1-9:1; the thermally conductive filler is a mixture of magnesium oxide with varying particle sizes. While the thermally conductive plastic prepared by this invention can achieve good thermal conductivity, it requires the addition of more than 60% thermally conductive filler to achieve this, and further improvement is needed. Summary of the Invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, the present invention provides a composite material with thermal conductivity, its preparation method and application.

[0005] This invention first provides a composite material with thermal conductivity, which comprises the following raw material components in parts by weight:

[0006] 80-150 parts polyamide resin; 20-40 parts thermally conductive filler; 5-15 parts flame retardant; 1-5 parts dispersant; 1-3 parts antioxidant.

[0007] This invention enables the prepared composite material to have thermal conductivity by adding a novel thermally conductive filler to polyamide resin.

[0008] Furthermore, the present invention can also help improve the flame retardant properties of polyamide resin by adding flame retardants.

[0009] Preferably, the thermally conductive composite material comprises the following raw material components in parts by weight:

[0010] 100-120 parts polyamide resin; 20-30 parts thermally conductive filler; 5-10 parts flame retardant; 1-3 parts dispersant; 1-2 parts antioxidant.

[0011] Most preferably, the thermally conductive composite material comprises the following raw material components in parts by weight:

[0012] 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant; 3 parts dispersant; 2 parts antioxidant.

[0013] Preferably, the thermally conductive filler is composed of boron nitride and carbon nanotubes.

[0014] This invention incorporates a thermally conductive filler composed of boron nitride and carbon nanotubes, which enables the prepared composite material to have better thermal conductivity.

[0015] Preferably, the weight ratio of boron nitride to carbon nanotubes in the thermally conductive filler is 3 to 5:1.

[0016] Most preferably, the weight ratio of boron nitride to carbon nanotubes in the thermally conductive filler is 4:1.

[0017] Preferably, the thermally conductive filler is a modified thermally conductive filler;

[0018] The modified thermally conductive filler is prepared by the following method:

[0019] Boron nitride and carbon nanotubes were added to water, followed by the addition of sodium lignosulfonate and stirred until homogeneous to obtain a boron nitride-carbon nanotube mixture.

[0020] Cerium nitrate was added to a boron nitride-carbon nanotube mixture, followed by sodium hydroxide. After stirring for 2-4 hours, the solid was separated to obtain product A.

[0021] Product A was subjected to constant temperature treatment at 300-500℃ for 1-3 hours to obtain product B; product B was then used to obtain the modified thermally conductive filler.

[0022] In further research, the inventors surprisingly discovered that adding a modified thermally conductive filler prepared by modifying boron nitride and carbon nanotubes using the above method to polyamide resin can significantly improve the thermal conductivity of the prepared composite material compared to adding an unmodified thermally conductive filler composed of boron nitride and carbon nanotubes.

[0023] Furthermore, the inventors were surprised to discover in their further research that adding the modified thermally conductive filler prepared by modifying boron nitride and carbon nanotubes using the above method to polyamide resin can significantly improve the electromagnetic shielding performance of the prepared composite material compared to adding the unmodified thermally conductive filler composed of boron nitride and carbon nanotubes.

[0024] Preferably, the carbon nanotubes are multi-walled carbon nanotubes.

[0025] Preferably, the ratio of boron nitride, carbon nanotubes and water is 3-5 kg: 1 kg: 25-50 L.

[0026] The most preferred ratio of boron nitride, carbon nanotubes and water is 4 kg: 1 kg: 30 L.

[0027] Preferably, the ratio of sodium lignosulfonate to water is 0.3-1 kg: 25-50 L.

[0028] The most preferred ratio of sodium lignosulfonate to water is 0.6 kg: 30 L.

[0029] Preferably, the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 25-50 L: 0.3-0.5 kg: 1.2-2.5 kg.

[0030] Most preferably, the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0031] More preferably, the modified thermally conductive filler further includes the following steps:

[0032] Product B is added to water, followed by a modifier. After stirring at 40–80°C for 3–5 hours, the solid is separated and dried to obtain the modified thermally conductive filler.

[0033] In further research, the inventors discovered that adding modified thermally conductive fillers to polyamide resins, after further treatment with modifiers, can further improve or significantly enhance the thermal conductivity and electromagnetic shielding performance of the prepared composite materials compared to modified thermally conductive fillers without modifier treatment.

[0034] Preferably, the ratio of product B to modifier and water is 1 kg: 0.2-0.4 kg: 4-8 L.

[0035] Most preferably, the ratio of product B to modifier and water is 1 kg: 0.3 kg: 6 L.

[0036] The modifier is selected from one or more of bis(dioctyloxypyrophosphate) ethylene titanate, pentadecylfluorooctanoate ammonium, and sodium dodecylbenzenesulfonate.

[0037] The modifier is composed of bis(dioctyloxypyrophosphate) ethylene titanate, pentadecylfluorooctanoate ammonium, and sodium dodecylbenzenesulfonate.

[0038] Preferably, the weight ratio of bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctanoate, and sodium dodecylbenzenesulfonate is 1-3:3-6:1-3.

[0039] Most preferably, the weight ratio of bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctanoate, and sodium dodecylbenzenesulfonate is 2:5:2.

[0040] Further research by the inventors revealed that the selection of the modifier is crucial. While adding a modified thermally conductive filler to polyamide resin, obtained by further treatment with a single modifier such as bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctanoate, or sodium dodecylbenzenesulfonate, can further improve the thermal conductivity and electromagnetic shielding performance of the prepared composite material compared to untreated filler, the improvement is not significant. Only by adding a modified thermally conductive filler to polyamide resin, obtained by further treatment with a modifier composed of bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctanoate, and sodium dodecylbenzenesulfonate, can the thermal conductivity and electromagnetic shielding performance of the prepared composite material be significantly improved.

[0041] Preferably, the flame retardant is selected from aluminum hydroxide or magnesium hydroxide.

[0042] Preferably, the dispersant is selected from ethylene bis-stearamide.

[0043] Preferably, the antioxidant is selected from antioxidant 1010.

[0044] The present invention also provides a method for preparing the above-mentioned composite material with thermal conductivity, which includes the following steps:

[0045] The polyamide resin, thermally conductive filler, flame retardant, dispersant and antioxidant are mixed evenly, and then melt-extruded through a twin-screw extruder to obtain the thermally conductive composite material.

[0046] Beneficial effects: This invention provides a novel composite material with thermal conductivity; research shows that the composite material of this invention not only has good thermal conductivity but also good electromagnetic shielding performance, and has important application value. Detailed Implementation

[0047] The present invention will be further explained below with reference to specific embodiments, but the specific embodiments do not limit the present invention in any way.

[0048] The polyamide resin used in the following examples is polyamide resin of grade 101L manufactured by DuPont, USA; all other raw materials whose sources are not specified are conventional raw materials that can be purchased in the art.

[0049] Example 1: Preparation of a thermally conductive composite material

[0050] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0051] The thermally conductive filler is composed of boron nitride and multi-walled carbon nanotubes in a weight ratio of 4:1.

[0052] Preparation method: Polyamide resin, thermally conductive filler, flame retardant, dispersant and antioxidant are mixed evenly, and then melt-extruded through a twin-screw extruder to obtain the composite material with thermal conductivity.

[0053] Example 2: Preparation of a thermally conductive composite material

[0054] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0055] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0056] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0057] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0058] (3) After treating product A at 400℃ for 2 hours, product B is obtained; product B is then taken to obtain the modified thermally conductive filler.

[0059] Example 3: Preparation of a thermally conductive composite material

[0060] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0061] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0062] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0063] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0064] (3) Product A was kept at 400℃ for 2 hours to obtain product B;

[0065] (4) Add product B to water, then add modifier, stir at 60°C for 4 hours, separate the solid, and dry the solid to obtain the modified thermally conductive filler; wherein, the ratio of product B to modifier and water is 1kg:0.3kg:6L; the modifier is bis(dioctyloxypyrophosphate) ethylene titanate.

[0066] Example 4: Preparation of a thermally conductive composite material

[0067] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0068] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0069] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0070] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0071] (3) Product A was kept at 400℃ for 2 hours to obtain product B;

[0072] (4) Add product B to water, then add modifier, stir at 60°C for 4 hours, separate the solid, and dry the solid to obtain the modified thermally conductive filler; wherein, the ratio of product B to modifier and water is 1kg:0.3kg:6L; the modifier is ammonium pentadecanoate.

[0073] Example 5: Preparation of a thermally conductive composite material

[0074] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0075] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0076] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0077] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0078] (3) Product A was kept at 400℃ for 2 hours to obtain product B;

[0079] (4) Add product B to water, then add modifier, stir at 60°C for 4 hours, separate the solid, and dry the solid to obtain the modified thermally conductive filler; wherein, the ratio of product B to modifier and water is 1kg:0.3kg:6L; the modifier is sodium dodecylbenzenesulfonate.

[0080] Example 6: Preparation of a thermally conductive composite material

[0081] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0082] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0083] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0084] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0085] (3) Product A was kept at 400℃ for 2 hours to obtain product B;

[0086] (4) Add product B to water, then add modifier, stir at 60°C for 4 hours, separate the solid, and dry the solid to obtain the modified thermally conductive filler; wherein, the ratio of product B to modifier and water is 1kg:0.3kg:6L; the modifier is composed of bis(dioctyloxypyrophosphate) ethylene titanate and pentadecylfluorooctanoate in a weight ratio of 2:5.

[0087] Example 7: Preparation of a thermally conductive composite material

[0088] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0089] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0090] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0091] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0092] (3) Product A was kept at 400℃ for 2 hours to obtain product B;

[0093] (4) Add product B to water, then add modifier, stir at 60°C for 4 hours, separate the solid, and dry the solid to obtain the modified thermally conductive filler; wherein, the ratio of product B to modifier and water is 1kg:0.3kg:6L; the modifier is composed of bis(dioctyloxypyrophosphate) ethylene titanate and sodium dodecylbenzenesulfonate in a weight ratio of 1:1.

[0094] Example 8: Preparation of a thermally conductive composite material

[0095] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0096] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0097] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0098] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0099] (3) Product A was kept at 400℃ for 2 hours to obtain product B;

[0100] (4) Add product B to water, then add modifier, stir at 60°C for 4 hours, separate the solid, and dry the solid to obtain the modified thermally conductive filler; wherein, the ratio of product B to modifier and water is 1kg:0.3kg:6L; the modifier is composed of ammonium pentadecanoate and sodium dodecylbenzenesulfonate in a weight ratio of 5:2.

[0101] Example 9: Preparation of a thermally conductive composite material

[0102] Raw material composition by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant (magnesium hydroxide); 3 parts dispersant (ethylene bis-stearamide); 2 parts antioxidant (antioxidant 1010);

[0103] The thermally conductive filler is a modified thermally conductive filler; the modified thermally conductive filler is prepared by the following method:

[0104] (1) Add boron nitride and multi-walled carbon nanotubes to water, then add sodium lignosulfonate and stir until homogeneous to obtain a boron nitride-carbon nanotube mixture; wherein the ratio of boron nitride, multi-walled carbon nanotubes to water is 4kg:1kg:30L; the ratio of sodium lignosulfonate to water is 0.6kg:30L.

[0105] (2) Add cerium nitrate to the boron nitride-carbon nanotube mixture, then add sodium hydroxide, stir and react for 3 hours, then separate the solid to obtain product A; wherein the ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 30L:0.35kg:1.5kg.

[0106] (3) Product A was kept at 400℃ for 2 hours to obtain product B;

[0107] (4) Add product B to water, then add modifier, stir at 60°C for 4 hours, separate the solid, and dry the solid to obtain the modified thermally conductive filler; wherein, the ratio of product B to modifier and water is 1kg:0.3kg:6L; the modifier is composed of bis(dioctyloxypyrophosphate) ethylene titanate, pentadecylfluorooctanoate ammonium and sodium dodecylbenzenesulfonate in a weight ratio of 2:5:2.

[0108] The thermal conductivity of the thermally conductive composite materials prepared in Examples 1-9 was tested according to the method in ASTM E1461-2013; their electromagnetic shielding effectiveness was tested according to the method in ASTM D4935; the test results are shown in Table 1.

[0109] Table 1. Performance test results of the thermally conductive composite material of the present invention

[0110]

[0111] As can be seen from the experimental results in Table 1, the thermally conductive composite material prepared in Example 1 has a thermal conductivity of 1.98 W / (m·K); this indicates that the thermally conductive composite material prepared in this invention has good thermal conductivity.

[0112] As can be seen from the experimental results in Table 1, the thermal conductivity of the composite material prepared in Example 2 is significantly higher than that of the composite material prepared in Example 1. This indicates that adding the modified thermally conductive filler prepared by modifying boron nitride and carbon nanotubes by the method described in this invention to polyamide resin can significantly improve the thermal conductivity of the prepared composite material compared to adding the unmodified thermally conductive filler composed of boron nitride and carbon nanotubes.

[0113] As can be seen from the experimental results in Table 1, the thermally conductive composite materials prepared in Examples 3-9 have a thermal conductivity that is higher or significantly higher than that of the thermally conductive composite material prepared in Example 2. This indicates that adding a modified thermally conductive filler to polyamide resin after further treatment with a modifier can further improve or significantly improve the thermal conductivity of the prepared composite material compared to the modified thermally conductive filler obtained without modification.

[0114] As can be seen from the experimental results in Table 1, the thermal conductivity of the composite materials with thermal conductivity prepared in Examples 3 to 8 is improved compared with that of the composite material with thermal conductivity prepared in Example 2, but the improvement is not significant; the improvement is much smaller than that of the composite material with thermal conductivity prepared in Example 9. This demonstrates that the selection of the modifier in this invention is crucial. Adding a modified thermally conductive filler obtained by further treatment of the polyamide resin with a single modifier, such as bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctate, or sodium dodecylbenzene sulfonate, or adding a modified thermally conductive filler obtained by treatment with any two of the modifiers bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctate, and sodium dodecylbenzene sulfonate, does not significantly improve the thermal conductivity of the prepared composite material compared to the modified thermally conductive filler obtained without modification. Only by adding a modified thermally conductive filler obtained by further treatment of the polyamide resin with a modifier composed of bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctate, and sodium dodecylbenzene sulfonate can the thermal conductivity of the prepared composite material be significantly improved.

[0115] As can be seen from the experimental results in Table 1, the thermally conductive composite material prepared in Example 1 has an electromagnetic shielding effectiveness of 30.8 dB; this indicates that the thermally conductive composite material prepared in this invention has an electromagnetic shielding effect.

[0116] As can be seen from the experimental results in Table 1, the electromagnetic shielding effectiveness of the thermally conductive composite material prepared in Example 2 is significantly higher than that of the thermally conductive composite material prepared in Example 1. This indicates that adding the modified thermally conductive filler prepared by modifying boron nitride and carbon nanotubes by the method described in this invention to polyamide resin can significantly improve the electromagnetic shielding effect of the prepared composite material compared to adding the unmodified thermally conductive filler composed of boron nitride and carbon nanotubes.

[0117] As can be seen from the experimental results in Table 1, the electromagnetic shielding effectiveness of the thermally conductive composite materials prepared in Examples 3-9 is higher or significantly higher than that of the thermally conductive composite material prepared in Example 2. This indicates that adding modified thermally conductive fillers to polyamide resin after further treatment with modifiers can further improve or significantly improve the electromagnetic shielding effectiveness of the prepared composite materials compared to modified thermally conductive fillers without modification.

[0118] As can be seen from the experimental results in Table 1, the electromagnetic shielding effectiveness of the thermally conductive composite materials prepared in Examples 3 to 8 is improved compared with that of the thermally conductive composite material prepared in Example 2, but the improvement is not significant; the improvement is much smaller than that of the thermally conductive composite material prepared in Example 9. This demonstrates that the selection of the modifier in this invention is crucial. Adding a modified thermally conductive filler obtained by further treatment of the polyamide resin with a single modifier, such as bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctate, or sodium dodecylbenzene sulfonate, or adding a modified thermally conductive filler obtained by treatment with any two of the modifiers bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctate, and sodium dodecylbenzene sulfonate, does not significantly improve the electromagnetic shielding performance of the prepared composite material compared to the modified thermally conductive filler obtained without modification. Only by adding a modified thermally conductive filler obtained by further treatment of the polyamide resin with a modifier composed of bis(dioctyloxypyrophosphate) ethylene titanate, ammonium pentadecylfluorooctate, and sodium dodecylbenzene sulfonate can the electromagnetic shielding performance of the prepared composite material be significantly improved.

Claims

1. A composite material with thermal conductivity, characterized in that, The raw material components comprise the following parts by weight: 80-150 parts polyamide resin; 20-40 parts thermally conductive filler; 5-15 parts flame retardant; 1-5 parts dispersant; 1-3 parts antioxidant; The thermally conductive filler is a modified thermally conductive filler; The modified thermally conductive filler is prepared by the following method: Boron nitride and carbon nanotubes were added to water, followed by the addition of sodium lignosulfonate and stirred until homogeneous to obtain a boron nitride-carbon nanotube mixture. Cerium nitrate was added to a boron nitride-carbon nanotube mixture, followed by sodium hydroxide. After stirring for 2-4 hours, the solid was separated to obtain product A. Product A was subjected to constant temperature treatment at 300~500°C for 1~3 hours to obtain product B; Product B is added to water, followed by the modifier. After stirring at 40-80°C for 3-5 hours, the solid is separated and dried to obtain the modified thermally conductive filler. The modifier is composed of bis(dioctyloxypyrophosphate) ethylene titanate, pentadecylfluorooctanoate ammonium, and sodium dodecylbenzene sulfonate. The weight ratio of bis(dioctyloxypyrophosphate) ethylene titanate, pentadecylfluorooctanoate ammonium, and sodium dodecylbenzene sulfonate is 1-3:3-6:1-3.

2. The composite material with thermal conductivity according to claim 1, characterized in that, The raw material components comprise the following parts by weight: 100-120 parts polyamide resin; 20-30 parts thermally conductive filler; 5-10 parts flame retardant; 1-3 parts dispersant; 1-2 parts antioxidant.

3. The thermally conductive composite material according to claim 1, characterized in that, The raw material components comprise the following parts by weight: 110 parts polyamide resin; 25 parts thermally conductive filler; 10 parts flame retardant; 3 parts dispersant; 2 parts antioxidant.

4. The composite material with thermal conductivity according to claim 1, characterized in that, The ratio of boron nitride, carbon nanotubes and water is 3~5kg:1kg:25~50L.

5. The thermally conductive composite material according to claim 1, characterized in that, The ratio of boron nitride, carbon nanotubes and water is 4 kg: 1 kg: 30 L.

6. The thermally conductive composite material according to claim 1, characterized in that, The ratio of sodium lignosulfonate to water is 0.3~1kg:25~50L.

7. The thermally conductive composite material according to claim 1, characterized in that, The ratio of sodium lignosulfonate to water is 0.6 kg: 30 L.

8. The thermally conductive composite material according to claim 1, characterized in that, The ratio of boron nitride-carbon nanotube mixture to cerium nitrate and sodium hydroxide is 25~50L:0.3~0.5kg:1.2~2.5kg.

9. A method for preparing the thermally conductive composite material according to any one of claims 1 to 8, characterized in that, It includes the following steps: The polyamide resin, thermally conductive filler, flame retardant, dispersant and antioxidant are mixed evenly, and then melt-extruded through a twin-screw extruder to obtain the thermally conductive composite material.

Images