High-toughness and high-thermal-conductivity nylon composite material and preparation method thereof

Abstract

The invention discloses a high-toughness and high-thermal-conductivity nylon composite material and a preparation method thereof. The composite material is prepared from the following raw materials in parts by mass: 35 to 55 parts of nylon resin, 20 to 45 parts of heat-conducting filler, 5 to 25 parts of reinforcing filler, 0.1 to 1 part of dispersing agent, 0.5 to 1.5 parts of main compatilizer, 0.5 to 1.5 parts of auxiliary compatilizer, 1 to 3 parts of nucleating agent and 0.1 to 0.5 part of first antioxidant, the heat-conducting filler comprises at least one of graphene filler and graphite filler; the main compatilizer is prepared from the following raw materials in parts by mass: 7 to 9 parts of polypropylene, 0.6 to 0.8 part of maleic anhydride, 0.6 to 0.8 part of vinyl trimethoxy silane, 0.04 to 0.06 part of an initiator, 0.1 to 0.3 part of a second antioxidant and 0.2 to 0.4 part of silicone powder; the preparation method of the main compatilizer comprises the following steps: uniformly mixing the raw materials of the main compatilizer, performing melt extrusion through a first double-screw extruder, and performing cooling and drying to obtain the main compatilizer.

Description

Technical Field

[0001] This invention relates to the field of nylon composite materials, and more specifically to a high-toughness, high-thermal-conductivity nylon composite material and its preparation method. Background Technology

[0002] In high-power applications such as automobiles, lighting equipment, and home appliances, metal materials are typically used as the primary heat conduction and heat dissipation medium. Currently, to achieve lightweight structures and reduce manufacturing costs, the market trend is gradually shifting towards using thermally conductive plastics to replace metal materials with lower mechanical performance requirements. To achieve good thermal conductivity comparable to metals, a large amount of graphene filler is usually added to nylon. This results in nylon plastic having high rigidity and low toughness. However, for high thermally conductive nylon materials used as metal substitutes, high rigidity is not an advantage; low flexibility and low toughness can lead to damage during assembly and use.

[0003] The following existing technologies were found through a search: Patent specification CN116285318A discloses a lightweight, thermally conductive engineering plastic and its preparation method, belonging to the field of engineering plastics technology. The method includes the following raw materials in parts by weight: 100 parts polyamide resin (nylon), 60-70 parts modified graphene, 812 parts nano-alumina, 23 parts lubricant, and 0.6-0.8 parts antioxidant. The modified graphene and nano-alumina are placed in a high-speed mixer, followed by the addition of polyamide resin, lubricant, and antioxidant. The high-speed mixer is then turned on to obtain a homogeneous mixture. The mixture is then extruded and granulated using a twin-screw extruder to obtain the engineering plastic. This patented technology uses polyamide resin (nylon) as the matrix, thus possessing lightweight and high-strength characteristics. By modifying and adding graphene, the thermal conductivity, toughness, and flame retardancy of the engineering plastic can be simultaneously improved, resulting in a lightweight, highly thermally conductive engineering plastic.

[0004] Patent specification CN103740092A discloses a high thermal conductivity graphene / nylon composite material and its preparation method. By weight, it comprises 30-80 parts nylon, 4-8 parts expandable graphite, 0.5-1.5 parts amphiphilic pyrene graft, 1-20 parts highly oriented silicon nitride fiber, 1-15 parts carbon fiber, 5-10 parts boron nitride, 0.02-4 parts high-temperature resistant additive, 0.02-0.8 parts antioxidant, 1-3 parts anti-hydrolysis agent, and 2-6 parts toughening agent. This patented technology employs a novel thermal conductivity additive to improve the thermal conductivity of nylon. This thermal conductivity additive is graphene prepared from expandable graphite and amphiphilic pyrene graft through a liquid-phase ultrasonic exfoliation method. The advantages of this novel thermal conductivity additive are: it allows graphene to be uniformly dispersed in the matrix resin and strengthens the interfacial adhesion between graphene and nylon, improving compatibility. Summary of the Invention

[0005] This invention provides a high-toughness, high-thermal-conductivity nylon composite material and its preparation method, belonging to the field of polymer material modification technology. This invention's high-toughness, high-thermal-conductivity nylon composite material solves the problems of low deflection, poor toughness, and uneven thermal conductivity caused by uneven dispersion of thermally conductive fillers in graphite / graphene-filled thermally conductive nylon composite materials by optimizing interfacial compatibility and thermal conductivity processes.

[0006] The specific technical solution is as follows: In a first aspect, the present invention provides a high-toughness, high-thermal-conductivity nylon composite material, wherein, by mass parts, the raw material composition of the high-toughness, high-thermal-conductivity nylon composite material comprises: 35-55 parts of nylon resin (e.g., 40 parts), 20-45 parts of thermally conductive filler (e.g., 40 parts), 5-25 parts of reinforcing filler (e.g., 12 parts), 0.1-1 part of dispersant (e.g., 0.6 parts, 0.8 parts), 0.5-1.5 parts of main compatibilizer (e.g., 1 part), 0.5-1.5 parts of auxiliary compatibilizer, 1-3 parts of nucleating agent (e.g., 1.5 parts), and 0.1-0.5 parts of first antioxidant; The thermally conductive filler includes at least one of graphene filler and graphite filler; The main compatibilizer comprises, by weight, 7-9 parts (e.g., 8 parts), 0.6-0.8 parts (e.g., 0.7 parts), 0.6-0.8 parts (e.g., 0.7 parts), 0.04-0.06 parts (e.g., 0.05 parts), 0.1-0.3 parts (e.g., 0.2 parts), and 0.2-0.4 parts (e.g., 0.3 parts) of silicone powder. The preparation method of the main compatibilizer includes: mixing the raw materials of the main compatibilizer and then melting and extruding them through a first twin-screw extruder, cooling and drying them to obtain the main compatibilizer.

[0007] While small molecules of silane coupling agents can improve material compatibility, their small molecular structure significantly increases the material's rigidity and flexural modulus, leading to brittleness. The main compatibilizer of this invention, however, has a larger molecular structure and better flexibility, significantly avoiding this problem. This main compatibilizer enhances the bonding and coating ability with reinforcing fillers such as glass fiber and thermally conductive fillers such as graphene, while exhibiting similar compatibility with resins, thus greatly improving the interfacial compatibility of the material without increasing its rigidity.

[0008] The high-toughness, high-thermal-conductivity nylon composite material, wherein the nylon resin is preferably nylon 6. The characteristic viscosity of the nylon 6 is preferably 1.6~3.2 dL / g, for example 2.0 dL / g, 2.4 dL / g, 2.8 dL / g, etc. The nylon resin can be a combination of nylon 6 with different characteristic viscosities.

[0009] The high-toughness and high-thermal-conductivity nylon composite material, wherein the graphene filler preferably includes one or more of single-layer graphene, few-layer (2 to 10 layers, such as 3 layers) graphene, and graphene oxide.

[0010] The high-toughness, high-thermal-conductivity nylon composite material preferably includes at least one morphology of spherical and dendritic graphene fillers. Spherical graphene fillers exhibit better processing stability. Dendritic graphene fillers possess higher thermal conductivity.

[0011] The high-toughness, high-thermal-conductivity nylon composite material, wherein the reinforcing filler preferably includes one or more of glass fiber, carbon fiber, basalt fiber, and glass microspheres.

[0012] The high-toughness, high-thermal-conductivity nylon composite material, wherein the nucleating agent preferably includes a primary nucleating agent and a secondary nucleating agent. The primary nucleating agent preferably includes one or more of talc, sodium lignite, silica, and montmorillonite. The secondary nucleating agent preferably includes one or more of CHB-3C, NAV-101, and CAV-102. The mass ratio of the primary nucleating agent to the secondary nucleating agent is preferably 1.5~2.5:1, for example, 2:1.

[0013] The high-toughness, high-thermal-conductivity nylon composite material, wherein the first antioxidant preferably comprises a first primary antioxidant and a first secondary antioxidant. The first primary antioxidant preferably comprises at least one of antioxidant 1010 and antioxidant 1098. The first secondary antioxidant preferably comprises at least one of antioxidant 626 and antioxidant 168. The mass ratio of the first primary antioxidant to the first secondary antioxidant is preferably 1 to 2:1, for example, 1.5:1.

[0014] Preferably, in the high-toughness, high-thermal-conductivity nylon composite material, the dispersant comprises one or more of phenyltrimethoxysilane, hexadecyltrimethoxysilane, and γ-mercaptopropyltriethoxysilane. More preferably, the dispersant is a compound dispersant comprising two or more of phenyltrimethoxysilane, hexadecyltrimethoxysilane, and γ-mercaptopropyltriethoxysilane.

[0015] In some preferred embodiments, the high-toughness, high-thermal-conductivity nylon composite material uses a dispersant comprising γ-mercaptopropyltriethoxysilane and hexadecyltrimethoxysilane. The mass ratio of γ-mercaptopropyltriethoxysilane to hexadecyltrimethoxysilane in the dispersant is preferably 2-4:1, for example, 3:1, and more preferably 3-4:1. Hexadecyltrimethoxysilane has an aliphatic long chain, which is beneficial for improving the dispersibility of the thermally conductive filler while maintaining the toughness of the composite material.

[0016] Preferably, in the high-toughness, high-thermal-conductivity nylon composite material, the initiator includes dicumyl peroxide (DCP).

[0017] Preferably, in the high-toughness, high-thermal-conductivity nylon composite material, the second antioxidant comprises a second primary antioxidant and a second secondary antioxidant. The second primary antioxidant preferably comprises antioxidant 1076. The second secondary antioxidant preferably comprises antioxidant 168. The mass ratio of the second primary antioxidant to the second secondary antioxidant is preferably 1 to 2:1.

[0018] Preferably, in the high-toughness, high-thermal-conductivity nylon composite material, the silicone powder comprises polydimethylsiloxane.

[0019] Preferably, in the high-toughness, high-thermal-conductivity nylon composite material, the main compatibilizer is granules.

[0020] Preferably, in the high-toughness, high-thermal-conductivity nylon composite material, the preparation method of the main compatibilizer involves adding the raw material of the main compatibilizer to the main feed port of the first twin-screw extruder, setting the temperature of each section of the barrel of the first twin-screw extruder to 180-230℃, and the screw speed to 350-450 rpm.

[0021] The high-toughness, high-thermal-conductivity nylon composite material, wherein the compatibilizer preferably includes one or more of polyethylene wax, ethylene bis-fatty acid amide, silicone masterbatch, and pentaerythritol stearate.

[0022] In a second aspect, the present invention provides a method for preparing the high-toughness, high-thermal-conductivity nylon composite material described in the first aspect, comprising: The raw materials of the high-toughness and high-thermal-conductivity nylon composite material, excluding the reinforcing filler, are mixed to obtain a mixed material; The mixed material and the reinforcing filler are respectively added to the main feed port and the side feed port of the second twin-screw extruder, and then melted, extruded, cooled and dried to obtain the high-toughness and high-thermal-conductivity nylon composite material.

[0023] Preferably, in the preparation method of the high-toughness and high-thermal-conductivity nylon composite material, the temperature of each section of the barrel of the second twin-screw extruder is set to 180-250℃, and the screw speed is 350-450 rpm.

[0024] Compared with the prior art, the beneficial effects of this invention are as follows: This invention solves the technical problem of reduced deflection and toughness caused by excessive graphite / graphene filler in current high thermal conductivity nylon, which leads to assembly difficulties and easy cracking. It develops a nylon composite material that has both high toughness and uniform dispersion, as well as high thermal conductivity.

[0025] To achieve good thermal conductivity, nylon composites typically require the addition of significant amounts of thermally conductive fillers such as graphite / graphene. However, these fillers are prone to agglomeration, resulting in only a slight improvement in thermal conductivity even with increased filler content. To address this, existing technologies often employ small-molecule silane coupling agents such as KH550 to improve the dispersion of the thermally conductive fillers and their compatibility with the nylon matrix. However, the introduction of these small-molecule silane coupling agents leads to a significant increase in the rigidity of the nylon composite, which is detrimental to its practical applications. This invention, through formulation improvement and the use of a specific main compatibilizer, successfully solves the above technical problems, improving the dispersion of the thermally conductive fillers without significantly increasing the rigidity of the composite material, thereby obtaining a nylon composite material that simultaneously possesses high toughness and high thermal conductivity. Detailed Implementation

[0026] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0027] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0028] Unless otherwise specified, "parts" in the specific implementation method refers to parts by mass.

[0029] The preparation method of the main compatibilizer used in the specific embodiment includes: premixing 8 parts of polypropylene PP9012D, 0.7 parts of maleic anhydride, 0.7 parts of vinyltrimethoxysilane, 0.05 parts of initiator DCP, 0.2 parts of compound antioxidant (antioxidant 1076 and antioxidant 168 in a 1:1 mass ratio), and 0.3 parts of silicone powder polydimethylsiloxane. The mixture is then melt-sheared, extruded, cooled, dried, and pelletized into granules using a twin-screw extruder to obtain the main compatibilizer. The temperature of each section of the twin-screw extruder barrel is set to 180-230℃, and the screw speed is 450 rpm.

[0030] The preparation process of the following examples of nylon composite materials is the same, including: mixing raw materials other than reinforcing fillers to obtain a mixed material; adding the mixed material and the reinforcing fillers to the main feed port and side feed port of a twin-screw extruder, respectively; setting the temperature of each section of the twin-screw extruder barrel to 180-250℃ and the screw speed to 450rpm; and obtaining the nylon composite material through melting, extrusion, cooling and drying.

[0031] Example 1: Raw material composition: Nylon 6: 20 parts each of characteristic viscosity 1.6 dL / g and 2.8 dL / g; Graphene filler: 40 parts of spherical few-layer graphene; Reinforcing filler: 12 parts of glass fiber; Compound antioxidant: 0.3 parts of antioxidant 1098 and 0.2 parts of antioxidant 168; Compound nucleating agent: 1 part of 10000 mesh talc powder and 0.5 parts of CHB-3C.

[0032] Example 2: The raw material composition was improved based on Example 1 by adding a compound compatibilizer: 1 part KH-550 and 0.5 parts silicone masterbatch.

[0033] Example 3: The raw material composition is based on Example 1, with the addition of a compound compatibilizer: 1 part of main compatibilizer and 0.5 parts of silicone masterbatch.

[0034] Example 4: The raw material composition was improved based on Example 3 by adding a compound dispersant: 0.4 parts of γ-mercaptopropyltriethoxysilane and 0.2 parts of hexadecyltrimethoxysilane.

[0035] Example 5: The raw material composition was improved based on Example 3 by adding a compound dispersant: 0.6 parts of γ-mercaptopropyltriethoxysilane and 0.2 parts of hexadecyltrimethoxysilane.

[0036] Example 6: The raw material composition was improved based on Example 3 by adding a compound dispersant: 0.8 parts of γ-mercaptopropyltriethoxysilane and 0.2 parts of hexadecyltrimethoxysilane.

[0037] The mechanical properties and thermal conductivity of the nylon composite materials obtained in the above examples are shown in Table 1 below.

[0038] Table 1 Based on the test results of Examples 1-6, compared with ordinary thermally conductive nylons such as magnesium hydroxide-filled nylon, graphene filler, due to its small particle size, provides thermal conductivity while significantly increasing the rigidity of the material. This can be seen from the flexural modulus and deflection, which show that the material is not easy to bend.

[0039] The test results of Examples 1-3 show that only by adding a certain amount of organosilicon dispersant compatibilizer, which acts as an intermediate between graphene and resin, can the stability of the material be significantly enhanced. In terms of physical properties, although the thermal conductivity of Example 2 is improved to some extent, the added KH-550, after being removed from the solvent, exhibits a small molecular structure, which also significantly increases the rigidity of the material. In contrast, the main compatibilizer added in Example 3 is a PP-organosilicon resin, a large molecular structure with certain molecular chain segments, which does not lead to an increase in rigidity due to the introduction of small molecules. Furthermore, the large molecular organosilicon long chains of the main compatibilizer can better coat graphene, enhancing its compatibility with the resin. A comparison of Examples 3-6 shows that adding an appropriate amount of dispersant can effectively improve the dispersibility of graphene in the resin and reduce agglomeration. Because the graphene is more uniformly dispersed, the material's deflection does not decrease, and the flexural modulus does not increase significantly. Compared to Example 3, the thermal conductivity of Example 6 is increased by 20%. Taking into account both mechanical properties and cost, the graphene-filled nylon composite material of Example 5 is more competitive in the heat dissipation market.

[0040] As can be seen from the above scheme, the present invention solves the technical problem that graphene thermally conductive nylon is difficult to pass the toughness test due to its low mechanical properties caused by excessive filling of ultra-small particle size thermally conductive fillers, by improving the formula, and develops a high-toughness thermally conductive and flame-retardant nylon composite material.

[0041] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A high-toughness, high-thermal-conductivity nylon composite material, characterized in that, The raw material composition of the high-toughness and high-thermal-conductivity nylon composite material, by weight, includes: 35-55 parts nylon resin, 20-45 parts thermally conductive filler, 5-25 parts reinforcing filler, 0.1-1 part dispersant, 0.5-1.5 parts main compatibilizer, 0.5-1.5 parts auxiliary compatibilizer, 1-3 parts nucleating agent, and 0.1-0.5 parts primary antioxidant; The thermally conductive filler includes at least one of graphene filler and graphite filler; The main compatibilizer comprises, by mass parts, 7-9 parts polypropylene, 0.6-0.8 parts maleic anhydride, 0.6-0.8 parts vinyltrimethoxysilane, 0.04-0.06 parts initiator, 0.1-0.3 parts secondary antioxidant, and 0.2-0.4 parts silicone powder. The preparation method of the main compatibilizer includes: mixing the raw materials of the main compatibilizer and then melting and extruding them through a first twin-screw extruder, cooling and drying them to obtain the main compatibilizer.

2. The high-toughness, high-thermal-conductivity nylon composite material according to claim 1, characterized in that, The nylon resin is nylon 6, and the characteristic viscosity of nylon 6 is 1.6~3.2 dL / g.

3. The high-toughness, high-thermal-conductivity nylon composite material according to claim 1, characterized in that, The graphene filler includes one or more of monolayer graphene, few-layer graphene, and graphene oxide. The graphene filler has at least one morphology, including spherical and dendritic shapes. The reinforcing filler includes one or more of glass fiber, carbon fiber, basalt fiber, and glass microspheres; The nucleating agent includes a primary nucleating agent and a secondary nucleating agent; the primary nucleating agent includes one or more of talc, sodium lignite, silica, and montmorillonite; the secondary nucleating agent includes one or more of CHB-3C, NAV-101, and CAV-102; the mass ratio of the primary nucleating agent to the secondary nucleating agent is 1.5~2.5:1; The first antioxidant includes a first primary antioxidant and a first secondary antioxidant; the first primary antioxidant includes at least one of antioxidant 1010 and antioxidant 1098; the first secondary antioxidant includes at least one of antioxidant 626 and antioxidant 168; the mass ratio of the first primary antioxidant to the first secondary antioxidant is 1 to 2:

1.

4. The high-toughness, high-thermal-conductivity nylon composite material according to claim 1, characterized in that, The dispersant includes one or more of phenyltrimethoxysilane, hexadecyltrimethoxysilane, and γ-mercaptopropyltriethoxysilane.

5. The high-toughness, high-thermal-conductivity nylon composite material according to claim 4, characterized in that, The dispersant includes γ-mercaptopropyltriethoxysilane and hexadecyltrimethoxysilane; In the dispersant, the mass ratio of γ-mercaptopropyltriethoxysilane to hexadecyltrimethoxysilane is 2~4:

1.

6. The high-toughness, high-thermal-conductivity nylon composite material according to claim 1, characterized in that, The initiator includes dicumyl peroxide; The second antioxidant includes a second primary antioxidant and a second secondary antioxidant; the second primary antioxidant includes antioxidant 1076; the second secondary antioxidant includes antioxidant 168; the mass ratio of the second primary antioxidant to the second secondary antioxidant is 1~2:1; The silicone powder includes polydimethylsiloxane; The main compatibilizer is in granular form.

7. The high-toughness, high-thermal-conductivity nylon composite material according to claim 1, characterized in that, In the preparation method of the main compatibilizer, the raw material of the main compatibilizer is added to the main feed port of the first twin-screw extruder, and the temperature of each section of the barrel of the first twin-screw extruder is set to 180-230℃, and the screw speed is 350-450 rpm.

8. The high-toughness, high-thermal-conductivity nylon composite material according to claim 1, characterized in that, The compatibilizer includes one or more of polyethylene wax, ethylene bis-fatty acid amide, silicone masterbatch, and pentaerythritol stearate.

9. The method for preparing the high-toughness, high-thermal-conductivity nylon composite material according to any one of claims 1 to 8, characterized in that, include: The raw materials of the high-toughness and high-thermal-conductivity nylon composite material, excluding the reinforcing filler, are mixed to obtain a mixed material; The mixed material and the reinforcing filler are respectively added to the main feed port and the side feed port of the second twin-screw extruder, and then melted, extruded, cooled and dried to obtain the high-toughness and high-thermal-conductivity nylon composite material.

10. The method for preparing the high-toughness, high-thermal-conductivity nylon composite material according to claim 9, characterized in that, The temperature of each section of the barrel of the second twin-screw extruder is set to 180-250℃, and the screw speed is 350-450 rpm.

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