A high-performance, high-thermal-conductivity plastic and its preparation method

Abstract

This invention relates to the field of thermally conductive plastics technology, specifically to a high-performance, high-thermal-conductivity plastic and its preparation method. The high-performance, high-thermal-conductivity plastic, by weight, comprises the following raw materials: 40-60 parts nylon resin, 5-10 parts flame retardant, 20-35 parts thermally conductive filler, 10-15 parts glass fiber, 1-2 parts coupling agent, and 1-2 parts antioxidant. The high-performance, high-thermal-conductivity plastic prepared by this invention possesses excellent thermal conductivity while also exhibiting good mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive plastics technology, specifically to a high-performance, high-thermal-conductivity plastic and its preparation method. Background Technology

[0002] Thermally conductive plastics are used in consumer electronics, new energy vehicles, medical equipment, home appliances, construction, and other fields. They are typically polymer materials composed of thermally conductive fillers such as ceramic particles, carbon fibers, and graphene, combined with engineering plastic matrices such as PPS, PA, PC, and PPA. These materials combine the lightweight, insulation, and easy-to-process properties of plastics with excellent thermal conductivity.

[0003] Traditional thermally conductive materials are mostly metals such as Ag, Cu, and Al, and metal oxides such as Al₂O₃, MgO, and BeO, as well as other non-metallic materials such as graphite, carbon black, Si₃N₄, and AlN. Generally, polymer materials themselves have poor thermal conductivity and are poor conductors of heat. Only by filling them with fillers of high thermal conductivity can the thermal conductivity of the material be increased. The thermal conductivity of the filler itself and its distribution within the polymer matrix determine the overall thermal conductivity of the material. How to maximize the formation of a thermally conductive network within the system to achieve effective heat conduction is a crucial issue that must be considered.

[0004] Patent CN105086431A discloses a thermally conductive, insulating, and flame-retardant nylon alloy for LEDs and its preparation method. This nylon alloy is composed of the following components by weight percentage: 5-80% first nylon resin, 5-75% magnesium oxide, 1-30% flame retardant, 0.1-1.5% antioxidant, 0.1-3% lubricant, and 1-15% compatibilizer. This invention, by selectively applying magnesium oxide whiskers to the nylon alloy, yields a polymer material with good thermal conductivity, insulation, aging resistance, and flame retardant properties, which can replace metals in the production of LED lamp heat sinks. However, poor dispersion of magnesium oxide whiskers in the nylon alloy may affect the thermal conductivity of different parts of the nylon alloy.

[0005] Patent CN118546521A discloses a graphene-modified high thermal conductivity plastic and its preparation method, which is prepared from nylon matrix resin, graphene-modified polyaniline resin, surface-modified aramid fiber, and nano-high thermal conductivity insulating filler; the mass of surface-modified aramid fiber accounts for 6-8% of the total mass of the high thermal conductivity plastic; the mass of nano-high thermal conductivity insulating filler accounts for 24-28% of the total mass of the high thermal conductivity plastic; the mass of graphene-modified polyaniline resin accounts for 28-36% of the total mass of the high thermal conductivity plastic; the nylon matrix resin is composed of PA66 and PA612 in a mass ratio of (6-8):(2-4). The nano-high thermal conductivity insulating filler is composed of spherical alumina, spherical aluminum nitride, and boron nitride nanosheets. The spherical alumina is a graphene-modified spherical alumina. The high thermal conductivity plastic prepared in this application has good thermal conductivity and heat dissipation. However, the poor dispersion of graphene in the nylon matrix resin may affect the mechanical properties of the high thermal conductivity plastic.

[0006] Therefore, there is an urgent need in the market for a high thermal conductivity plastic with excellent mechanical properties. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of this invention is to obtain a high-performance, high-thermal-conductivity plastic with excellent mechanical properties.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides a high-performance, high-thermal-conductivity plastic, comprising the following raw materials by weight: 40-60 parts of nylon resin, 5-10 parts of flame retardant, 20-35 parts of thermally conductive filler, 10-15 parts of glass fiber, 1-2 parts of coupling agent, and 1-2 parts of antioxidant.

[0010] This application presents a high-performance, high-thermal-conductivity plastic prepared by blending nylon resin, flame retardant, thermally conductive filler, glass fiber, coupling agent, and antioxidant. This plastic possesses excellent mechanical and thermal conductivity properties.

[0011] In some embodiments, the nylon resin is a combination of nylon 6 and nylon 66.

[0012] Preferably, the mass ratio of nylon 6 to nylon 66 is (1.5-2):1.

[0013] In some embodiments, the method for preparing the thermally conductive filler includes the following steps:

[0014] A1. In an ice-water bath, mix graphene, concentrated sulfuric acid and sodium nitrate, stir until homogeneous, add potassium permanganate, maintain the temperature at 0℃, continue stirring for 8-12 hours, add deionized water to dilute, then add hydrogen peroxide and stir for 30-60 minutes, filter to obtain a solid, put the solid into 1-3 mol / L hydrochloric acid and stir for 20-30 minutes, centrifuge, wash and dry to obtain graphene oxide;

[0015] A2. Add aluminum isopropoxide and hexamethylenetetramine to an aqueous ethanol solution and stir at 50-60°C for 3-5 hours to obtain an aluminum precursor; add graphene oxide and polyvinylpyrrolidone obtained in step A1 to deionized water, sonicate for 2-4 hours, add to the aluminum precursor, stir at 60-80°C for 4-6 hours, dry, and calcine at 800-1000°C for 3-5 hours in an ammonia atmosphere to obtain aluminum nitride-coated graphene.

[0016] A3. Add aluminum nitride-coated graphene and KH-550 silane coupling agent to an ethanol aqueous solution, stir at 30-40℃ for 2-4 hours, filter and dry to obtain a solid product;

[0017] A4. Add the solid product obtained in step A3, tetrabutyl titanate, and hydrogenated cinnamic acid to DMF, stir at 60-80℃ for 4-6 hours, filter and dry to obtain the thermally conductive filler.

[0018] This application prepares aluminum nitride-coated graphene by reacting graphene oxide with an aluminum precursor and then calcining it. The resulting thermally conductive filler, obtained by reacting graphene oxide with KH550 silane coupling agent and hydrogenated cinnamic acid, is then added to a nylon thermally conductive plastic system, which enables the plastic to have excellent thermal conductivity and mechanical properties. This may be because, on the one hand, aluminum nitride coating of graphene can weaken the interaction forces between graphene sheets, resulting in better dispersion of the thermally conductive filler in nylon resin. The aluminum nitride coating layer can also inhibit the sliding of graphene sheets, thus increasing the tensile strength of the high thermal conductivity plastic compared to the pure graphene-filled system. Furthermore, the phonon transport of aluminum nitride is complementary to the electron / phonon conduction of graphene, reducing interfacial thermal resistance. In addition, aluminum nitride can act as a "thermal bridge" to connect graphene sheets, forming a three-dimensional thermally conductive pathway, giving nylon plastic excellent thermal conductivity. On the other hand, the reaction of KH550 silane coupling agent with hydrogenated cinnamic acid yields amide groups, allowing the same amide segments as nylon resin to be grafted onto the aluminum nitride-coated graphene, further improving the dispersion of aluminum nitride-coated graphene in nylon resin. Moreover, the benzene ring on hydrogenated cinnamic acid can generate π-π conjugation with graphene, enhancing the continuity of the phonon transport path and improving the thermal conductivity of nylon plastic.

[0019] In some embodiments, the mass ratio of graphene oxide to aluminum isopropoxide in step A2 is 1:(3-5).

[0020] This application, by limiting the ratio of graphene oxide to aluminum isopropoxide, enables a small portion of graphene exposed on the surface of the conductive filler to generate π-π conjugation with the benzene rings on hydrogenated cinnamic acid, thereby enhancing the continuity of the phonon transport path and improving the thermal conductivity of nylon plastic.

[0021] In some embodiments, the mass ratio of aluminum nitride-coated graphene and KH-550 silane coupling agent in step A3 is 1:(0.1-0.3).

[0022] In some embodiments, the mass ratio of the solid product to hydrogenated cinnamic acid in step A4 is 1:(0.05-0.15).

[0023] This application enables high thermal conductivity plastics to possess both excellent thermal conductivity and excellent mechanical properties by limiting the ratio of aluminum nitride-coated graphene, KH-550 silane coupling agent, solid products, and hydrogenated cinnamic acid. This may be because the ratio allows some residual hydrogenated cinnamic acid in the system, whose carboxyl groups can form hydrogen bonds with the amide groups on the nylon resin, weakening the hydrogen bond network between nylon molecular chains, reducing chain segment movement resistance, and making the thermally conductive filler easier to disperse in the nylon resin.

[0024] In some embodiments, the flame retardant is one or more of halogen-based flame retardants, metal hydroxide flame retardants, phosphorus-based flame retardants, and nitrogen-based flame retardants.

[0025] In some embodiments, the glass fiber has a diameter of 10-20 μm and a length of 0.2-1 mm.

[0026] In some embodiments, the antioxidant is selected from one or more of hindered phenols, phosphites, thioesters, benzofurans, and hydroxylamine antioxidants.

[0027] Preferably, the antioxidant is antioxidant 1010.

[0028] Another aspect of the present invention provides a method for preparing high-performance, high-thermal-conductivity plastics, comprising the following steps: first, pre-treating thermally conductive fillers with glass fibers and coupling agents by ball milling; then, melt-blending and extruding with nylon resin, flame retardant and antioxidant; the twin-screw extrusion temperature is 250-280℃ and the rotation speed is 200-400rpm to obtain high-performance, high-thermal-conductivity plastics.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The high-performance, high-thermal-conductivity plastic prepared by blending nylon resin, flame retardant, thermally conductive filler, glass fiber, coupling agent and antioxidant has excellent mechanical and thermal properties.

[0031] (2) The aluminum nitride-coated graphene prepared by reacting graphene oxide and aluminum precursor and then calcining can weaken the interaction force between graphenes, so that the thermally conductive filler has better dispersibility in nylon resin. The aluminum nitride coating layer can also inhibit the sliding of graphene sheets, so that the tensile strength of the high thermal conductivity plastic is higher than that of the pure graphene filling system. Moreover, the phonon transport of aluminum nitride is complementary to the electron / phonon conduction of graphene, which reduces the interfacial thermal resistance. Furthermore, aluminum nitride can act as a "thermal bridge" to connect graphene sheets, forming a three-dimensional thermally conductive pathway, so that nylon plastic has excellent thermal conductivity.

[0032] (3) The thermally conductive filler of the present invention is obtained by reacting aluminum nitride-coated graphene with KH550 silane coupling agent and hydrogenated cinnamic acid. The reaction of KH550 silane coupling agent with hydrogenated cinnamic acid yields amide groups, which graft amide segments identical to those of nylon resin onto the aluminum nitride-coated graphene, thereby further improving the dispersibility of aluminum nitride-coated graphene in nylon resin. Furthermore, the benzene ring on the hydrogenated cinnamic acid can generate π-π conjugation with graphene, enhancing the continuity of phonon transport paths and improving the thermal conductivity of nylon plastic. Detailed Implementation

[0033] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0034] In the following examples and comparative examples, except for the thermally conductive filler, all other compounds and related reagents used were commercially available. Specifically, the nylon 6 was BASF FP10KT; the nylon 66 was BASF A3K A3X2G7; the graphene was 5-10 μm nano-graphene sheets purchased from Beijing Deco Island Gold Technology Co., Ltd.; the glass fiber had a diameter of 10-20 μm and a length of 0.2-1 mm; and the coupling agent was a titanate coupling agent, model NDZ-101.

[0035] Preparation Example 1

[0036] The preparation method of thermally conductive filler-1 includes the following steps:

[0037] A1. In an ice-water bath, mix 10g of nano-graphene sheets, 230ml of 98wt% concentrated sulfuric acid and 6g of sodium nitrate, stir well, add 30g of potassium permanganate, keep the temperature at 0℃, continue stirring for 10h, add deionized water to dilute, then add 70ml of hydrogen peroxide and stir for 45min, filter to obtain a solid, put the solid into 300ml of 2mol / L hydrochloric acid and stir for 25min, centrifuge, wash and dry to obtain graphene oxide;

[0038] A2. Add 40g of aluminum isopropoxide and 8g of hexamethylenetetramine to 200ml of 75wt% ethanol aqueous solution and stir at 55℃ for 4h to obtain aluminum precursor; add 10g of graphene oxide obtained in step A1 and 3g of polyvinylpyrrolidone to 100ml of deionized water, sonicate for 3h, add to aluminum precursor, stir at 70℃ for 5h, dry, and calcine at 900℃ for 4h in an ammonia atmosphere to obtain aluminum nitride coated graphene.

[0039] A3. Add 10g of aluminum nitride-coated graphene and 2g of KH-550 silane coupling agent to 100ml of 90wt% ethanol aqueous solution, stir at 35℃ for 3h, filter and dry to obtain solid product.

[0040] A4. Add 10g of the solid product obtained in step A3, 0.2g of tetrabutyl titanate and 1g of hydrogenated cinnamic acid to 100ml of DMF, stir at 70℃ for 5h, filter and dry to obtain thermally conductive filler-1.

[0041] Preparation Example 2

[0042] The preparation method of thermally conductive filler-2 is the same as that of preparation example 1, except that the amount of aluminum isopropoxide added is 55g.

[0043] Preparation Example 3

[0044] The preparation method of thermally conductive filler-3 is the same as that of preparation example 1, except that the amount of KH-550 silane coupling agent added is 4g.

[0045] Preparation Example 4

[0046] The preparation method of thermally conductive filler-4 is the same as that of preparation example 1, except that the amount of hydrogenated cinnamic acid added is 2g.

[0047] Example 1

[0048] A high-performance, high-thermal-conductivity plastic, by weight, comprises the following raw materials: 50 parts nylon resin, 7 parts melamine cyanurate, 27 parts thermally conductive filler-1, 12 parts glass fiber, 1.5 parts titanate coupling agent, and 1.5 parts antioxidant 1010.

[0049] The preparation method of high-performance, high-thermal-conductivity plastic in this embodiment includes the following steps: First, the thermally conductive filler-1 is ball-milled with glass fiber and titanate coupling agent at a ball-to-material ratio of 15:1 for 4 hours. Then, it is melt-blended and extruded with nylon resin, melamine cyanurate and antioxidant 1010 at a twin-screw extrusion temperature of 265°C and a rotation speed of 300 rpm to obtain high-performance, high-thermal-conductivity plastic.

[0050] The nylon resin is a composition of nylon 6 and nylon 66 in a mass ratio of 1.5:1.

[0051] Example 2

[0052] A high-performance, high-thermal-conductivity plastic, by weight, comprises the following raw materials: 40 parts nylon resin, 5 parts melamine cyanurate, 20 parts thermally conductive filler-1, 10 parts glass fiber, 1 part titanate coupling agent, and 1 part antioxidant 1010.

[0053] The preparation method of high-performance, high-thermal-conductivity plastic in this embodiment includes the following steps: First, the thermally conductive filler-1 is ball-milled with glass fiber and titanate coupling agent at a ball-to-material ratio of 15:1 for 4 hours. Then, it is melt-blended and extruded with nylon resin, melamine cyanurate and antioxidant 1010 at a twin-screw extrusion temperature of 250°C and a rotation speed of 400 rpm to obtain high-performance, high-thermal-conductivity plastic.

[0054] The nylon resin is a composition of nylon 6 and nylon 66 in a mass ratio of 1.5:1.

[0055] Example 3

[0056] A high-performance, high-thermal-conductivity plastic, by weight, comprises the following raw materials: 60 parts nylon resin, 10 parts melamine cyanurate, 35 parts thermally conductive filler-1, 15 parts glass fiber, 2 parts titanate coupling agent, and 2 parts antioxidant 1010.

[0057] The preparation method of high-performance, high-thermal-conductivity plastic in this embodiment includes the following steps: First, the thermally conductive filler-1 is ball-milled with glass fiber and titanate coupling agent at a ball-to-material ratio of 15:1 for 4 hours. Then, it is melt-blended and extruded with nylon resin, melamine cyanurate and antioxidant 1010 at a twin-screw extrusion temperature of 280°C and a rotation speed of 200 rpm to obtain high-performance, high-thermal-conductivity plastic.

[0058] The nylon resin is a composition of nylon 6 and nylon 66 in a mass ratio of 2:1.

[0059] Example 4

[0060] A high-performance, high-thermal-conductivity plastic and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that thermally conductive filler-1 is replaced with thermally conductive filler-2 in equal amounts.

[0061] Example 5

[0062] A high-performance, high-thermal-conductivity plastic and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that thermally conductive filler-1 is replaced with thermally conductive filler-3 in equal amounts.

[0063] Example 6

[0064] A high-performance, high-thermal-conductivity plastic and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that thermally conductive filler-1 is replaced with thermally conductive filler-4 in equal amounts.

[0065] Example 7

[0066] A high-performance, high-thermal-conductivity plastic and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the thermally conductive filler-1 is replaced with an equal amount of nano-graphene sheets.

[0067] Performance testing

[0068] The performance of the high-performance, high-thermal-conductivity plastics obtained in the above embodiments and comparative examples was tested:

[0069] (1) Thermal conductivity: The thermal conductivity was determined according to the standard test method of ASTM D5470-06 for thermally conductive and electrically insulating materials.

[0070] (2) Bending strength: Bending strength was determined according to the standard test method of ASTM D790-03 for bending properties of unreinforced and reinforced plastics and electrical insulating materials.

[0071] The test results are shown in Table 1:

[0072] Table 1

[0073] Group Thermal conductivity W / (mK) Flexural strength (MPa) Example 1 2.92 215.53 Example 2 2.97 212.36 Example 3 2.84 217.85 Example 4 2.55 214.52 Example 5 2.63 212.47 Example 6 2.65 212.65 Example 7 1.89 182.34

[0074] As shown in Table 1, the high-performance, high-thermal-conductivity plastics of Examples 1-3 possess excellent thermal conductivity and mechanical properties. A comparison between Examples 4 and 1 reveals that altering the ratio of graphene oxide to aluminum isopropoxide worsens the continuity of the enhanced phonon transport path, thus reducing the thermal conductivity of the plastic. A comparison between Examples 5 and 6 and Example 1 shows that changing the ratio of aluminum nitride-coated graphene to KH-550 silane coupling agent or solid product to hydrogenated cinnamic acid makes it less likely for the hydrogen bond network between nylon molecular chains to be weakened, thereby reducing the thermal conductivity and mechanical properties of the high-thermal-conductivity plastic. A comparison between Example 7 and Example 1 shows that when nano-graphene sheets are used directly, the resulting plastic exhibits poor thermal conductivity and mechanical properties.

[0075] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high-performance, high-thermal-conductivity plastic, characterized in that, By weight, it includes the following raw materials: 40-60 parts nylon resin, 5-10 parts flame retardant, 20-35 parts thermally conductive filler, 10-15 parts glass fiber, 1-2 parts coupling agent, and 1-2 parts antioxidant. The method for preparing the thermally conductive filler includes the following steps: A1. In an ice-water bath, mix graphene, concentrated sulfuric acid and sodium nitrate, stir until homogeneous, add potassium permanganate, maintain the temperature at 0℃, continue stirring for 8-12 hours, add deionized water to dilute, then add hydrogen peroxide and stir for 30-60 minutes, filter to obtain a solid, put the solid into 1-3 mol / L hydrochloric acid and stir for 20-30 minutes, centrifuge, wash and dry to obtain graphene oxide; A2. Add aluminum isopropoxide and hexamethylenetetramine to an aqueous ethanol solution and stir at 50-60°C for 3-5 hours to obtain an aluminum precursor; add graphene oxide and polyvinylpyrrolidone obtained in step A1 to deionized water, sonicate for 2-4 hours, add to the aluminum precursor, stir at 60-80°C for 4-6 hours, dry, and calcine at 800-1000°C for 3-5 hours in an ammonia atmosphere to obtain aluminum nitride-coated graphene. A3. Add aluminum nitride-coated graphene and KH-550 silane coupling agent to an ethanol aqueous solution, stir at 30-40℃ for 2-4 hours, filter and dry to obtain a solid product; A4. Add the solid product obtained in step A3, tetrabutyl titanate and hydrogenated cinnamic acid to DMF, stir at 60-80℃ for 4-6 hours, filter and dry to obtain thermally conductive filler. In step A2, the mass ratio of graphene oxide to aluminum isopropoxide is 1:(3-5); the mass ratio of aluminum isopropoxide to hexamethylenetetramine is 40:

8. In step A3, the mass ratio of aluminum nitride-coated graphene to KH-550 silane coupling agent is 1:(0.1-0.3). The mass ratio of the solid product to hydrogenated cinnamic acid in step A4 is 1:(0.05-0.15).

2. The high-performance, high-thermal-conductivity plastic according to claim 1, characterized in that, The nylon resin is a combination of nylon 6 and nylon 66.

3. The high-performance, high-thermal-conductivity plastic according to claim 1, characterized in that, The flame retardant is one or more of the following: halogenated flame retardant, metal hydroxide flame retardant, phosphorus-based flame retardant, and nitrogen-based flame retardant.

4. The high-performance, high-thermal-conductivity plastic according to claim 1, characterized in that, The glass fiber has a diameter of 10–20 μm and a length of 0.2–1 mm.

5. The high-performance, high-thermal-conductivity plastic according to claim 1, characterized in that, The antioxidant is selected from one or more of hindered phenols, phosphites, thioesters, benzofurans, and hydroxylamine antioxidants.

6. A method for preparing a high-performance, high-thermal-conductivity plastic according to any one of claims 1-5, characterized in that, The process includes the following steps: first, the thermally conductive filler is ball-milled and pretreated with glass fiber and coupling agent, and then melt-blended and extruded with nylon resin, flame retardant and antioxidant. The twin-screw extrusion temperature is 250-280℃ and the speed is 200-400rpm to obtain high-performance, high thermally conductive plastic.