Heat-conducting antistatic PE composite material and preparation method thereof

Abstract

The invention discloses a heat-conducting antistatic PE composite material and a preparation method thereof. The heat-conducting antistatic PE composite material is prepared from the following raw materials in parts by weight: 90 parts of PE, 3-7 parts of an antistatic agent XG / CNTs (at) PDA, 2-4 parts of a heat-conducting agent HNTs-SiO2-KH550, 0.5-1 part of an antioxidant 1010, 1-3 parts of polyethylene wax and 1 part of glycerol. The antistatic agent is based on a carbon nanotube, is subjected to compatibility modification by utilizing polydopamine, and then is compounded with a reinforcing component xanthan gum; the heat conduction agent is prepared by the following steps: homogenizing and modifying halloysite nanotubes, then combining the halloysite nanotubes with SiO2 with good heat conduction capability, and finally carrying out compatibility modification on the whole. The antistatic agent and the heat conduction agent are added into the PE material, so that the heat conduction and antistatic properties and mechanical properties of the PE material are effectively improved, and the PE composite material with excellent properties is prepared.

Description

Technical Field

[0001] The present invention belongs to the field of polymer composite processing, and particularly relates to a thermally conductive and antistatic PE composite material and a preparation method thereof. Background Art

[0002] Polyethylene (PE) is a polymer chain structure formed by the polymerization of ethylene molecules, and its output accounts for about 1 / 4 of the total plastic output. Due to its light weight, low price, strong stability and other characteristics, polyethylene materials have been widely used in modern industry. However, the inherent insulation of polyethylene materials causes static electricity to be generated during transportation by friction and when used in electronic devices. The static electricity is difficult to eliminate and gradually accumulates. When it reaches the critical point, it will cause fires and explosions. In addition, static electricity will cause dust absorption in medical devices, ultimately affecting the accuracy of the results. According to relevant surveys and statistics, static electricity has always been one of the main causes of fires and explosions. The global losses caused by static electricity may reach billions of dollars every year. Therefore, the insulation of polyethylene has become one of the main problems restricting its application.

[0003] At the same time, based on the continuous innovation of information technology, electronic devices have developed in the direction of being thin, light and small. If the generated heat cannot be effectively dissipated, the performance stability and service life of the device will face great threats. Therefore, there is an urgent need for high-efficiency polymer materials in the heat dissipation of electronic devices. Polyethylene materials have the advantages of easy processing, light weight, low cost, etc., and are widely used in fields such as modern electronic devices. However, crystal defects and crystal interfaces in polyethylene will seriously affect the heat transfer efficiency, resulting in a very low thermal conductivity (Tc) value (0.1 - 0.5 W / m·K). The Tc of the thermal conductive materials required for high-density integrated electronic devices is not less than 1 W / m·K. Therefore, traditional polyethylene materials can no longer meet the development needs of this field, and it is necessary to develop polyethylene composite materials with good thermal conductivity.

[0004] Based on this, the present invention proposes a thermally conductive and antistatic PE composite material and a preparation method thereof. Summary of the Invention

[0005] The object of the present invention is to provide a thermally conductive and antistatic PE composite material and a preparation method thereof. An antistatic agent and a thermal conductive agent are used to prepare a thermally conductive and antistatic PE composite material by means of melt blending. The antistatic agent is based on carbon nanotubes with stable chemical properties and excellent electrical conductivity, and PDA is used to modify its compatibility so that it can be evenly distributed in the polyethylene matrix. Then xanthan gum (XG) is compounded with CNTs@PDA as a reinforcing component, and the obtained antistatic agent not only has strong thermal stability, but also has excellent antistatic performance for the composite material prepared by melt blending with polyethylene resin, and the mechanical properties will also be greatly improved. The thermal conductive agent is based on RHNTs that can conduct heat flow. After homogenization modification, SiO2 is attached to the outer wall of the nanotube to form a structure similar to a grape cluster, and the overall compatibility modification is carried out. The two prepared modified fillers are melt-compounded with the polyethylene matrix resin to prepare a polyethylene composite material with excellent thermal conductivity, antistatic performance and greatly enhanced mechanical properties. The formula of the present invention is scientific and reasonable, and the technological process is simple and practical. By adding an antistatic agent and a thermal conductive agent, the produced PE composite material has excellent thermal conductivity, antistatic performance and mechanical properties.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A thermally conductive and antistatic PE composite material, wherein the raw material composition of the PE composite material is calculated by weight as follows: 90 parts of PE, 3-7 parts of an antistatic agent, 2-4 parts of a thermal conductive agent, 0.5-1 part of antioxidant 1010, 1-3 parts of polyethylene wax, and 1 part of glycerol; the antistatic agent is XG / CNTs@PDA, and the thermal conductive agent is HNTs-SiO2-KH550.

[0007] The preparation method steps of the above antistatic agent XG / CNTs@PDA are as follows: (1) Preparation of CNTs@PDA: Disperse 3 g of carbon nanotubes in 10 mL of anhydrous ethanol and 300 mg of hydrochloric acid dopamine in 100 mL of Tris-HCl buffer solution (concentration 1.6 g / L, pH = 8.5). The mixture is continuously stirred in a constant temperature reactor at 50 °C for 12 h, and after vacuum filtration, washing with deionized water and vacuum drying at 60 °C, CNTs@PDA powder is obtained.

[0008] (2)Preparation of XG / CNTs@PDA: Dissolve 4 g of xanthan gum and 4 g of glacial acetic acid in 250 mL of deionized water, and then stir for 30 min in a magnetic stirrer to form a homogeneous solution. Subsequently, add 3 g of CNTs@PDA powder, and dropwise add 5 g of citric acid aqueous solution (solution purity is 99.5%) at a stirring rate of 500 rpm until CNTs@PDA is uniformly dispersed in the solution. Continue to stir for 6 h, then put it into a freeze dryer for freeze drying for 24 h, and obtain XG / CNTs@PDA after grinding.

[0009] The preparation steps of the above thermal conductive agent HNTs-SiO2-KH550 are as follows: (1)Preparation of HNTs: Add 4 g of 3-aminopropyltriethoxysilane to a mixed solution formed by 150 mL of ethanol and 30 mL of deionized water and stir for 1 hour, then add 1 g of halloysite nanotubes (RHNTs) and ultrasonically treat for 0.5 hour. Reflux the solution at 80 °C and stir for 24 hours. After filtration, wash the precipitate with ethanol and dry at 60 °C for 10 h to obtain HNTs.

[0010] (2)Preparation of HNTs-SiO2: Add 1 g of HNTs to 44 mL of deionized water and ultrasonically treat for 2 hours, then add 4.4 g of citric acid and continue ultrasonically treat for 2 hours (solution A). Dissolve 20 g of sodium silicate in 250 mL of deionized water, heat to 80 °C, and add 2.5 mL of ethanol dropwise thereto (solution B). Slowly and evenly drop solution A into solution B, adjust the pH value of the reaction environment to 6 with sulfuric acid (2.5 mol / L), then add 160 mL of absolute ethanol, continue to stir for 1 hour, and then let it stand overnight for aging. The precipitate obtained after centrifugation is washed three times with deionized water and ethanol, and dried at 60 °C for 12 h. Obtain HNTs-SiO2 powder.

[0011] (3)Preparation of HNTs-SiO2-KH550: Add 2 mL of 3-aminopropyltriethoxysilane (KH550) to 200 mL of ethanol solution (95%), ultrasonically treat for 1 h, then add 8 g of HNTs-SiO2 powder and stir at 80 °C for 6 h. After filtration, wash it repeatedly with ethanol and deionized water, and vacuum dry at 60 °C for 24 h to obtain the thermal conductive filler HNTs-SiO2-KH550.

[0012] A preparation method of a thermal conductive and antistatic PE composite material includes the following steps: (1) After uniformly mixing the antistatic agent XG / CNTs@PDA, the thermal conductive agent HNTs-SiO2-KH550, the antioxidant 1010, the polyethylene wax, and glycerol, they were further mixed uniformly with PE particles in a high-speed mixer. The rotation speed of the high-speed mixer was 300 r / min, the temperature was 60 °C, and then they were placed in an oven at 60 °C and dried for 1 hour.

[0013] (2) The dried raw materials were added to a twin-screw extruder. The temperature of the first section of the twin-screw extruder was 180 °C, the second section was 175 °C, the third section was 170 °C, the fourth section was 165 °C, and the fifth section was 160 °C; the rotation speed of the screw was 10 r / min; and masterbatches were obtained by extrusion granulation.

[0014] (3) The masterbatches obtained from the twin-screw extruder and the granulator were dried in an oven at 60 °C for 1 hour and injection-molded using an injection molding machine. The temperatures from the feed inlet to the discharge outlet of the injection molding machine were: the temperature of the first section: 200 °C, the second section: 190 °C, the third section: 180 °C, the fourth section: 170 °C, the fifth section: 160 °C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, and a thermally conductive and antistatic PE composite material was obtained.

[0015] The beneficial effects of the present invention are as follows: (1) The synthesized antistatic agent XG / CNTs@PDA of the present invention not only has good electrical conductivity but also excellent thermal stability due to the presence of carbon nanotubes (CNTs). In addition, the compatibility of CNTs was modified using polydopamine, which can avoid the decrease in the mechanical properties of the composite material caused by the poor compatibility between carbon nanotubes and the polyethylene matrix and improve the dispersion degree of the antistatic agent in the polyethylene matrix. And xanthan gum was added as a reinforcing component, which not only improved the compatibility between the antistatic agent and polyethylene but also exerted its high-viscosity characteristics, greatly improving the mechanical properties of the composite material. Moreover, when the addition amount of the antistatic agent is relatively high, carbon nanotubes can form an electrically conductive pathway in the polyethylene matrix, making the antistatic performance of the composite material more excellent.

[0016] (2) The synthesized thermal conductive agent HNTs-SiO2-KH550 of the present invention is based on halloysite nanotubes for heat transfer and forms a structure similar to a grape cluster by attaching SiO2 outside the nanotubes. In this structure, halloysite nanotubes can quickly conduct heat, and SiO2 can store heat while having good thermal conductivity. After the compatibility of the filler with this structure was modified as a whole and melt-blended with polyethylene to prepare a composite material, when the addition amount of the thermal conductive agent is relatively high, a multi-dimensional thermal conductive network can be constructed in the composite material, greatly improving the thermal conductivity of the composite material while maintaining stable mechanical properties. Description of the Drawings

[0017] Figure 1 Fourier transform infrared spectrum of antistatic agent XG / CNTs@PDA.

[0018] Figure 2 Fourier transform infrared spectrum of thermal conductive agent HNTs-SiO2-KH550.

[0019] Figure 3 SEM image of CNTs@PDA.

[0020] Figure 4 SEM image of XG / CNTs@PDA.

[0021] Figure 5 SEM image of HNTs-SiO2-KH550.

[0022] Figure 6 SEM image of the thermally conductive and antistatic PE composite material prepared in Example 3 of the present invention. Detailed implementation manners

[0023] The present invention will be further described below in conjunction with specific embodiments to make the present invention easier to understand, but the present invention is not limited to these embodiments.

[0024] Example 1 1. Preparation of antistatic agent XG / CNTs@PDA: (1) Preparation of CNTs@PDA: Disperse 3 g of carbon nanotubes in 100 mL of Tris-HCl buffer solution (concentration 1.6 g / L, pH = 8.5), add 10 mL of absolute ethanol and 300 mg of dopamine hydrochloride. The above mixture is continuously stirred in a constant temperature reactor at 50 °C for 12 h, and after vacuum filtration, washing with deionized water and vacuum drying at 60 °C, the CNTs@PDA composite material is obtained.

[0025] (2) Preparation of XG / CNTs@PDA: Dissolve 4 g of xanthan gum (XG) and 4 g of glacial acetic acid in 250 mL of deionized water, and then stir in a magnetic stirrer for 30 min to form a homogeneous solution. Subsequently, add 3 g of CNTs@PDA powder, and dropwise add 5 g of citric acid aqueous solution (solution purity 99.5%) at a stirring rate of 500 rpm until CNTs@PDA is uniformly dispersed in the solution. After continuing to stir for 6 h, it is placed in a freeze dryer for freeze drying for 24 h and then ground to obtain XG / CNTs@PDA.

[0026] 2. Preparation of thermal conductive agent HNTs-SiO2-KH550: (1)Preparation of HNTs: 4 g of 3-aminopropyltriethoxysilane was added to a mixed solution formed by 150 mL of absolute ethanol and 30 mL of deionized water and stirred for 1 hour. Then, 1 g of halloysite nanotubes (RHNTs) was added and sonicated for 0.5 hour. The resulting solution was refluxed and stirred at 80 °C for 24 hours, filtered, washed with ethanol, and dried at 60 °C for 10 h to obtain HNTs.

[0027] (2)Preparation of HNTs-SiO2 composite filler: 1 g of HNTs was added to 44 mL of deionized water and sonicated for 2 hours, and 4.4 g of citric acid was added and sonicated for another 2 hours (solution A). 20 g of sodium silicate was dissolved in 250 mL of deionized water, heated to 80 °C, and 2.5 mL of absolute ethanol was added dropwise to the sodium silicate solution (solution B). Solution A was slowly and evenly added dropwise to solution B. The pH value of the reaction environment was adjusted to 6 with sulfuric acid (2.5 mol / L). Then, 160 mL of absolute ethanol was added and stirred for 1 hour, left to age overnight, and the precipitate obtained after centrifugation was washed three times with deionized water and ethanol and dried at 60 °C for 12 h to prepare the HNTs-SiO2 composite filler.

[0028] (3)Preparation of HNTs-SiO2-KH550: 2 mL of 3-aminopropyltriethoxysilane (KH550) was added to 200 mL of ethanol solution (95%) and sonicated for 1 h, and then 8 g of HNTs-SiO2 composite filler was added and stirred at 80 °C for 6 h. After filtration, it was washed multiple times with ethanol and deionized water and vacuum dried at 60 °C for 24 h to obtain the thermal conductive filler HNTs-SiO2-KH550.

[0029] 3. After uniformly mixing 3 parts by weight of XG / CNTs@PDA, 2 parts by weight of HNTs-SiO2-KH550, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax, and 1 part by weight of glycerol, they were further mixed uniformly with 90 parts by weight of PE particles in a high-speed mixer. The rotation speed of the high-speed mixer was 300 r / min, the temperature was 60 °C, and then it was placed in an oven at 60 °C and dried for 1 hour.

[0030] 4. The dried raw materials were added to a twin-screw extruder. The temperature of the first section of the twin-screw extruder was 180 °C, the second section was 175 °C, the third section was 170 °C, the fourth section was 165 °C, and the fifth section was 160 °C; the rotation speed of the screw was 10 r / min; and the mixed masterbatch was obtained by extrusion granulation.

[0031] 5. Dry the mixed masterbatch obtained in step (4) in an oven at 60 °C for 1 hour, and injection mold it using an injection molding machine. The temperatures of the injection molding machine from the feed inlet to the discharge outlet are as follows: the temperature of the first section: 200 °C, the temperature of the second section: 190 °C, the temperature of the third section: 180 °C, the temperature of the fourth section: 170 °C, the temperature of the fifth section: 160 °C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, to obtain a thermally conductive and antistatic PE composite material.

[0032] Figure 1 is the Fourier infrared spectrum of the antistatic agent XG / CNTs@PDA. In the infrared spectrum of CNT@PDA, the strong vibration band at 1591 cm -1 belongs to the in-plane stretching vibration of sp 2 hybridized carbon atoms, confirming the existence of graphene domains; the characteristic peak at 1395 cm -1 corresponds to the unique boundary vibration mode of carbon nanotubes. In the spectrum of XG / CNTs@PDA, the characteristic peak observed at 1625 cm -1 is the C=O stretching vibration of the amide bond, confirming the amideification reaction at the interface between xanthan gum and carbon nanotubes; the vibration peak at 1708 cm -1 originates from the C=O vibration of the ester group; after PDA modification, the C-O stretching vibration of phenol appears as an absorption peak at 1285 cm −1 , indicating that CNTs are modified by PDA. It shows that the antistatic agent XG / CNTs@PDA is successfully prepared.

[0033] Figure 2 is the Fourier infrared spectrum of the thermal conductive agent HNTs-SiO2-KH550. For RHNTs, 3697 and 3621 cm -1 correspond to the peak values of the stretching vibrations of the hydroxyl groups on the inner and outer surfaces of halloysite nanotubes respectively. The peak value at 538 cm -1 is the bending vibration peak of Al-O-Si. The infrared spectrum of HNTs-SiO2-KH550 shows the C-H deformation vibration peak (2924 cm -1 ) and the N-H stretching vibration peak (3448 cm -1 ) introduced by the silane coupling agent KH550. At the same time, the stretching vibration peaks of Si-O-Si and Si-OH can also be observed near 1096 and 962 cm -1 . This indicates the successful preparation of the HNTs-SiO2-KH550 thermal conductive agent.

[0034] Figure 3 is the SEM image of CNT@PDA. It can be clearly observed in the figure that the CNTs are intertwined with each other, and there are many small particles outside the tube walls, which indicates that CNT@PDA is successfully prepared.

[0035] Figure 4 This is a SEM image of the antistatic agent XG / CNTs@PDA prepared in this invention. Due to the presence of XG, the antistatic agent particles are larger, and short rod-like CNTs@PDA can be observed on the surface, indicating that they have formed a composite antistatic agent with XG.

[0036] Figure 5 This is a SEM image of the thermal conductive agent HNTs-SiO2-KH550 prepared in this invention. As can be seen in the image, the tubular HNTs are more dispersed due to modification. The bulk SiO2 is attached to the nanotube walls, forming a grape-like structure.

[0037] Example 2 1. The preparation process of the antistatic agent XG / CNTs@PDA and the thermal conductive agent HNTs-SiO2-KH550 was the same as that in Example 1; 2. 5 parts by weight of XG / CNTs@PDA, 3 parts by weight of HNTs-SiO2-KH550, 0.5 parts by weight of antioxidant 1010, 1 part by weight of polyethylene wax, and 1 part by weight of glycerol were mixed uniformly, and then mixed uniformly with 90 parts by weight of PE particles in a high-speed mixer at a speed of 300 r / min and a temperature of 60°C. The mixture was then placed in a 60°C oven to dry for 1 hour.

[0038] 3. Add the dried raw materials into a twin-screw extruder with the first section temperature of 180°C, the second section temperature of 175°C, the third section temperature of 170°C, the fourth section temperature of 165°C, and the fifth section temperature of 160°C; the screw speed is 10r / min; and the mixed masterbatch is obtained by extrusion granulation.

[0039] 4. Dry the mixed masterbatch in an oven at 60°C for 1 hour and then use an injection molding machine to mold it. The temperatures from the inlet to the outlet of the injection molding machine are: first section temperature: 200°C, second section temperature: 190°C, third section temperature: 180°C, fourth section temperature: 170°C, fifth section temperature: 160°C; injection pressure: 135MPa; holding pressure: 40MPa, to obtain a thermally conductive and antistatic PE composite material.

[0040] Example 3 1. The preparation process of the antistatic agent XG / CNTs@PDA and the thermal conductive agent HNTs-SiO2-KH550 was the same as that in Example 1; 2. Mix 7 parts by weight of XG / CNTs@PDA, 4 parts by weight of HNTs-SiO2-KH550, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax and 1 part by weight of glycerol evenly, and then mix them evenly with 90 parts by weight of PE particles in a high-speed mixer. The rotation speed of the high-speed mixer is 300 r / min, the temperature is 60 °C, and then place it in an oven at 60 °C and dry for 1 hour.

[0041] 3. Add the dried raw materials into a twin-screw extruder. The temperature of the first section of the twin-screw extruder is 180 °C, the second section is 175 °C, the third section is 170 °C, the fourth section is 165 °C, and the fifth section is 160 °C; the rotation speed of the screw is 10 r / min; obtain the masterbatch by extrusion granulation.

[0042] 4. Dry the masterbatch in an oven at 60 °C for 1 hour, and injection mold it with an injection molding machine. The temperatures of the injection molding machine from the feed port to the discharge port are the first section temperature: 200 °C, the second section temperature: 190 °C, the third section temperature: 180 °C, the fourth section temperature: 170 °C, the fifth section temperature: 160 °C; injection pressure: 135 MPa; holding pressure: 40 MPa, to obtain the thermally conductive and antistatic PE composite material.

[0043] Figure 6 This is the SEM image of the thermally conductive and antistatic PE composite material prepared in Example 3 of the present invention. It can be seen in the figure that the antistatic agent with larger particles and the thermally conductive agent with smaller particles. The two fillers are dispersed relatively evenly in the polyethylene matrix and have good compatibility with polyethylene. Therefore, both the mechanical properties and the thermally conductive and antistatic properties of the composite material are maintained well.

[0044] Example 4 1. The preparation processes of the antistatic agent XG / CNTs@PDA and the thermally conductive agent HNTs-SiO2-KH550 are the same as those in Example 1; 2. Mix 9 parts by weight of XG / CNTs@PDA, 5 parts by weight of HNTs-SiO2-KH550, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax and 1 part by weight of glycerol evenly, and then mix them evenly with 90 parts by weight of PE particles in a high-speed mixer. The rotation speed of the high-speed mixer is 300 r / min, the temperature is 60 °C, and then place it in an oven at 60 °C and dry for 1 hour.

[0045] 3. Add the dried raw materials into a twin-screw extruder. The temperature of the first section of the twin-screw extruder is 180 °C, the second section is 175 °C, the third section is 170 °C, the fourth section is 165 °C, and the fifth section is 160 °C; the rotation speed of the screw is 10 r / min; obtain the masterbatch by extrusion granulation.

[0046] 4. Dry the masterbatch at 60 °C in an oven for 1 hour, and then injection mold it using an injection molding machine. The temperatures from the feed inlet to the discharge outlet of the injection molding machine are as follows: the first-stage temperature: 200 °C, the second-stage temperature: 190 °C, the third-stage temperature: 180 °C, the fourth-stage temperature: 170 °C, the fifth-stage temperature: 160 °C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, to obtain a thermally conductive and antistatic PE composite material.

[0047] Comparative Example 1 1. Mix 90 parts by weight of PE particles, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax, and 1 part by weight of glycerol evenly in a high-speed mixer. The rotation speed of the high-speed mixer is 300 r / min, and the temperature is 60 °C. Then place it in an oven at 60 °C and dry for 1 hour.

[0048] 2. Add the dried raw materials to a twin-screw extruder. The temperatures of the first stage, the second stage, the third stage, the fourth stage, and the fifth stage of the twin-screw extruder are 180 °C, 175 °C, 170 °C, 165 °C, and 160 °C respectively; the rotation speed of the screw is 10 r / min; obtain the masterbatch by extrusion granulation.

[0049] 3. Dry the masterbatch obtained from the twin-screw extruder and the granulator in an oven at 60 °C for 1 hour, and then injection mold it using an injection molding machine. The temperatures from the feed inlet to the discharge outlet of the injection molding machine are as follows: the first-stage temperature: 200 °C, the second-stage temperature: 190 °C, the third-stage temperature: 180 °C, the fourth-stage temperature: 170 °C, the fifth-stage temperature: 160 °C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, to obtain a thermally conductive and antistatic PE composite material.

[0050] Comparative Example 2 1. The preparation method of the thermal conductive agent HNTs-SiO2-KH550 is the same as that in Example 1; 2. After mixing 5 parts by weight of CNTs, 3 parts by weight of HNTs-SiO2-KH550, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax, and 1 part by weight of glycerol evenly, then mix them evenly with 90 parts by weight of PE particles in a high-speed mixer. The rotation speed of the high-speed mixer is 300 r / min, and the temperature is 60 °C. Then place it in an oven at 60 °C and dry for 1 hour.

[0051] 3. Add the dried raw materials to a twin-screw extruder. The temperatures of the first stage, the second stage, the third stage, the fourth stage, and the fifth stage of the twin-screw extruder are 180 °C, 175 °C, 170 °C, 165 °C, and 160 °C respectively; the rotation speed of the screw is 10 r / min; obtain the masterbatch by extrusion granulation.

[0052] 4. Dry the mixed masterbatch at 60°C in an oven for 1 hour, and injection mold it using an injection molding machine. The temperatures of the injection molding machine from the feed inlet to the discharge outlet are as follows: the first-stage temperature: 200°C, the second-stage temperature: 190°C, the third-stage temperature: 180°C, the fourth-stage temperature: 170°C, the fifth-stage temperature: 160°C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, to obtain a thermally conductive and antistatic PE composite material.

[0053] Comparative Example 3 1. The preparation methods of the antistatic agent CNTs@PDA and the thermal conductive agent HNTs-SiO2-KH550 are the same as those in Example 1; 2. After uniformly mixing 5 parts by weight of CNTs@PDA, 3 parts by weight of HNTs-SiO2-KH550, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax, and 1 part by weight of glycerin, then uniformly mix them with 90 parts by weight of PE particles in a high-speed mixer. The rotation speed of the high-speed mixer is 300 r / min, the temperature is 60°C, and then place them in an oven at 60°C for drying for 1 hour.

[0054] 3. Add the dried raw materials to a twin-screw extruder. The temperature of the first stage of the twin-screw extruder is 180°C, the temperature of the second stage is 175°C, the temperature of the third stage is 170°C, the temperature of the fourth stage is 165°C, and the temperature of the fifth stage is 160°C; the rotation speed of the screw is 10 r / min; obtain the mixed masterbatch by extrusion granulation.

[0055] 4. Dry the mixed masterbatch at 60°C in an oven for 1 hour, and injection mold it using an injection molding machine. The temperatures of the injection molding machine from the feed inlet to the discharge outlet are as follows: the first-stage temperature: 200°C, the second-stage temperature: 190°C, the third-stage temperature: 180°C, the fourth-stage temperature: 170°C, the fifth-stage temperature: 160°C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, to obtain a thermally conductive and antistatic PE composite material.

[0056] Comparative Example 4 1. The preparation methods of the antistatic agent XG / CNTs@PDA and the thermal conductive agent HNTs-SiO2 are the same as those in Example 1; 2. After uniformly mixing 5 parts by weight of XG / CNTs@PDA, 3 parts by weight of HNTs-SiO2, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax, and 1 part by weight of glycerin, then uniformly mix them with 90 parts by weight of PE particles in a high-speed mixer. The rotation speed of the high-speed mixer is 300 r / min, the temperature is 60°C, and then place them in an oven at 60°C for drying for 1 hour.

[0057] 3. Add the dried raw materials into a twin-screw extruder. The temperature of the first section of the twin-screw extruder is 180 °C, the second section is 175 °C, the third section is 170 °C, the fourth section is 165 °C, and the fifth section is 160 °C; the rotational speed of the screw is 10 r / min; obtain the masterbatch through extrusion granulation.

[0058] 4. Dry the masterbatch in an oven at 60 °C for 1 hour, and then injection mold it with an injection molding machine. The temperatures from the feed inlet to the discharge outlet of the injection molding machine are as follows: the temperature of the first section: 200 °C, the second section: 190 °C, the third section: 180 °C, the fourth section: 170 °C, the fifth section: 160 °C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, to obtain the thermally conductive and antistatic PE composite material.

[0059] Comparative Example 5 1. The preparation method of the antistatic agent XG / CNTs@PDA is the same as that in Example 1; 2. Preparation steps of the thermal conductive agent HNTs: Add 4 g of 3-aminopropyltriethoxysilane into a mixed solution formed by 150 mL of ethanol and 30 mL of deionized water and stir for 1 hour, then add 1 g of halloysite nanotubes (RHNTs) and ultrasonically treat for 0.5 hour. Reflux and stir the solution at 80 °C for 24 hours. Filter by suction to obtain the final product, wash it with ethanol and dry it at 60 °C for 10 h. The obtained sample is HNTs.

[0060] 3. Mix 5 parts by weight of XG / CNTs@PDA, 3 parts by weight of HNTs, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax and 1 part by weight of glycerol evenly, and then mix them evenly with 90 parts by weight of PE particles in a high-speed mixer. The rotational speed of the high-speed mixer is 300 r / min, the temperature is 60 °C, and then place it in an oven at 60 °C and dry for 1 hour.

[0061] 4. Add the dried raw materials into a twin-screw extruder. The temperature of the first section of the twin-screw extruder is 180 °C, the second section is 175 °C, the third section is 170 °C, the fourth section is 165 °C, and the fifth section is 160 °C; the rotational speed of the screw is 10 r / min; obtain the masterbatch through extrusion granulation.

[0062] 5. Dry the masterbatch in an oven at 60 °C for 1 hour, and then injection mold it with an injection molding machine. The temperatures from the feed inlet to the discharge outlet of the injection molding machine are as follows: the temperature of the first section: 200 °C, the second section: 190 °C, the third section: 180 °C, the fourth section: 170 °C, the fifth section: 160 °C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, to obtain the thermally conductive and antistatic PE composite material.

[0063] Comparative Example 6 1. The preparation method of the antistatic agent XG / CNTs@PDA is the same as that in Example 1; 2. The preparation method of the thermal conductive agent HNTs-SiO2-KH570 includes the following steps: (1) Preparation of HNTs: Add 4 g of KH570 to a mixed solution formed by 150 mL of absolute ethanol and 30 mL of deionized water and stir for 1 hour, then add 1 g of halloysite nanotubes (RHNTs) and sonicate for 0.5 hour. Reflux the solution at 80 °C and stir for 24 hours. Filter to obtain the final product, wash with ethanol and dry at 60 °C for 10 h. The obtained sample is HNTs.

[0064] (2) Preparation of HNTs-SiO2 composite filler: Add 1 g of HNTs to 44 mL of deionized water and sonicate for 2 hours, add 4.4 g of citric acid and continue to sonicate for 2 hours (solution A). Dissolve 20 g of sodium silicate in 250 mL of deionized water, heat to 80 °C, and add 2.5 mL of ethanol dropwise to the sodium silicate solution (solution B). Slowly and evenly drop solution A into solution B. Adjust the pH value of the reaction environment to 6 with sulfuric acid (2.5 mol / L). Then, add 160 mL of absolute ethanol, continue to stir for 1 hour, and then leave it to age overnight. The precipitate obtained after centrifugation is washed three times with deionized water and absolute ethanol and dried at 60 °C for 12 h to obtain the HNTs-SiO2 composite filler.

[0065] (3) Preparation of HNTs-SiO2-KH570: Add 2 mL of KH570 to 200 mL of ethanol solution (95%), sonicate for 1 h, then add 8 g of HNTs-SiO2 composite filler and stir at 80 °C for 6 h. After filtration, wash with absolute ethanol and deionized water multiple times and dry under vacuum at 60 °C for 24 h to obtain the thermal conductive filler HNTs-SiO2-KH570.

[0066] 2. Mix 5 parts by weight of XG / CNTs@PDA, 3 parts by weight of HNTs-SiO2-KH570, 0.5 part by weight of antioxidant 1010, 1 part by weight of polyethylene wax and 1 part by weight of glycerol evenly, and then mix evenly with 90 parts by weight of PE particles in a high-speed mixer. The rotation speed of the high-speed mixer is 300 r / min, the temperature is 60 °C, and then place it in an oven at 60 °C and dry for 1 hour.

[0067] 3. Add the dried raw materials into a twin-screw extruder. The temperature of the first section of the twin-screw extruder is 180 °C, the second section is 175 °C, the third section is 170 °C, the fourth section is 165 °C, and the fifth section is 160 °C; the rotational speed of the screw is 10 r / min; obtain the masterbatch by extrusion granulation.

[0068] 4. Dry the masterbatch in an oven at 60 °C for 1 hour, and then injection mold it with an injection molding machine. The temperatures from the feed inlet to the discharge outlet of the injection molding machine are as follows: the temperature of the first section: 200 °C, the second section: 190 °C, the third section: 180 °C, the fourth section: 170 °C, the fifth section: 160 °C; the injection pressure: 135 MPa; the holding pressure: 40 MPa, and obtain the thermally conductive and antistatic PE composite material.

[0069] The performance test results of the PE composite materials obtained in the examples and comparative examples are shown in Table 1.

[0070] Performance test Table 1 Table 1 shows the performance test results of each example and each comparative example. It can be clearly seen from the above performance test results that for Examples 1-4, as the addition amounts of the thermal conductive agent and the antistatic agent increase, the tensile strength and elongation at break of the PE composite material show a trend of first increasing and then decreasing, the volume resistivity has been decreasing and the amplitude is relatively large, and the thermal conductivity has also been increasing, indicating that the antistatic performance and thermal conductivity of the composite material have been continuously improved. Among them, in Example 2, when the addition amount of the thermal conductive agent reaches 3 parts and the addition amount of the antistatic agent reaches 5 parts, the thermal conductivity and antistatic performance of the composite material are greatly improved. This is because the thermal conductive agent constructs a multi-dimensional thermal conduction network in the polyethylene matrix, enabling heat to be transferred quickly; at the same time, the antistatic agent also forms a conductive path in the matrix, and the composite material also has good antistatic ability. In Example 3, when the addition amount of the thermal conductive agent reaches 4 parts and the addition amount of the antistatic agent reaches 7 parts, except for a slight decrease in the elongation at break, the tensile strength of the composite material reaches the best, and the antistatic and thermal conductivity performances are very excellent. Compared with Example 3, in Example 4, the improvement amplitudes of the antistatic and thermal conductivity performances are smaller, but at this time, the tensile strength and elongation at break decrease more. This may be due to the agglomeration of the thermal conductive agent or the antistatic agent in the matrix material, resulting in a decrease in the mechanical properties. It can be seen from the comparison between Example 2 and Comparative Example 3 that the addition of the strengthening component XG in the antistatic agent can greatly improve the mechanical properties of the composite material. This is because XG can not only further improve the compatibility between the antistatic agent and polyethylene, but it can also exert its high-viscosity characteristics to improve the mechanical properties of the composite material. However, the antistatic performance of Comparative Example 3 is slightly improved compared with Example 2 because there are more carbon nanotubes in 5 parts by weight of CNTs@PDA in Comparative Example 3. It can be seen from the comparison between Comparative Examples 2 and 3 that after the carbon nanotubes are modified by polydopamine, their compatibility with the polyethylene matrix is better, which can reduce the influence of the addition of carbon nanotubes on the mechanical properties of the composite material. It can be seen from the comparison between Example 2 and Comparative Examples 4 and 5 that the overall modification of the thermal conductive agent can indeed improve its compatibility with the composite material and enhance the mechanical properties of the composite material. The comparison between Comparative Examples 4 and 5 can reflect that the composite material added with the HNTs-SiO2 thermal conductive agent has better thermal conductivity than the composite material only added with HNTs. This is only because the HNTs-SiO2 thermal conductive agent forms a structure similar to a grape cluster. When the addition amount of this structure of the thermal conductive agent is relatively high, it can construct a multi-dimensional thermal conduction network in the composite material, greatly improving the thermal conductivity of the composite material. It can be obtained from the comparison between Example 2 and Comparative Example 6 that the thermal conductive agent modified with KH550 has better thermal conductivity than the thermal conductive agent modified with KH570. This is because after being modified with KH550, the stacked RHNTs can be dispersed, not only enabling it to better form a grape cluster structure with SiO2, but also making the subsequent compatibility modification more sufficient, which makes the thermal conductivity and mechanical properties of the composite material better.

[0071] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A heat-conducting and antistatic PE composite material, characterized in that: The PE composite material, by weight, comprises 90 parts of PE, 3 - 7 parts of antistatic agent, 2 - 4 parts of heat conductive agent, 0.5 - 1 part of antioxidant 1010, 1 - 3 parts of polyethylene wax, and 1 part of glycerol; the antistatic agent is XG / CNTs@PDA, and the heat conductive agent is HNTs-SiO2-KH550.

2. The PE composite material according to claim 1, characterized in that: The preparation of the XG / CNTs@PDA comprises the following steps: (1) Preparation of CNTs@PDA: Disperse carbon nanotubes in Tris-HCl buffer solution, then add absolute ethanol and dopamine hydrochloride, stir at 50 °C for 12 h, and obtain CNTs@PDA powder after suction filtration, washing and drying. (2) Preparation of XG / CNTs@PDA: Dissolve xanthan gum and glacial acetic acid in deionized water to form a homogeneous solution, then add CNTs@PDA powder, and dropwise add 5 g of citric acid aqueous solution under stirring until CNTs@PDA is uniformly dispersed in the solution. Continue to stir for 6 h, and then obtain XG / CNTs@PDA after freeze-drying and grinding.

3. The preparation method according to claim 2, characterized in that: In step (1), the dosage ratio of the carbon nanotubes, Tris-HCl buffer solution, absolute ethanol and dopamine hydrochloride is 3 g:100 mL:10 mL:0.3 g.

4. The preparation method according to claim 2, characterized in that: In step (2), the dosage ratio of the xanthan gum, glacial acetic acid, CNTs@PDA and citric acid is 4:4:3:

5.

5. The PE composite material according to claim 1, wherein: The preparation of the HNTs-SiO2-KH550 comprises the following steps: (1) Preparation of HNTs: Add 4 g of 3-aminopropyltriethoxysilane to a mixed solution formed by 150 mL of ethanol and 30 mL of deionized water and stir for 1 hour, then add 1 g of halloysite nanotubes and ultrasonically treat for 0.5 h. Reflux the solution at 80 °C and stir for 24 hours, and obtain HNTs after suction filtration, washing and drying. (2) Preparation of HNTs-SiO2 composite filler: Add 1 g of HNTs to 44 mL of deionized water and ultrasonically treat for 2 h, then add 4.4 g of citric acid and continue to ultrasonically treat for 2 h to obtain solution A; dissolve 20 g of sodium silicate in 250 mL of deionized water, heat to 80 °C and then dropwise add 2.5 mL of ethanol to obtain solution B. Drop solution A into solution B, adjust the pH value to 6, then add 160 mL of absolute ethanol and continue to stir for 1 hour, and then let it stand overnight for aging. The precipitate obtained after centrifugation is washed and dried to obtain HNTs-SiO2 powder. (3) Preparation of HNTs-SiO2-KH550: Add 2 mL of 3-aminopropyltriethoxysilane to 200 mL of 95% ethanol solution and ultrasonically treat for 1 h, then add 8 g of HNTs-SiO2 powder and stir at 80 °C for 6 h. After filtration, washing and drying, the heat conductive agent HNTs-SiO2-KH550 is obtained.

6. A method for preparing the PE composite material according to claim 1, characterized in that: Comprises the following steps: (1) After uniformly mixing the antistatic agent XG / CNTs@PDA, the heat conductive agent HNTs-SiO2-KH550, the antioxidant 1010, the polyethylene wax and the glycerol, add them to a high-speed mixer and mix uniformly with PE, and then dry at 60 °C for 1 h. (2) Add the dried material into a twin-screw extruder and obtain masterbatch through extrusion granulation. (3) Dry the obtained masterbatch in an oven and then carry out injection molding to obtain the thermally conductive and antistatic PE composite material.

7. The preparation method according to claim 6, characterized in that: In step (1), the rotational speed of the high-speed mixer is 300 r / min and the temperature is 60°C.

8. The preparation method according to claim 6, characterized in that: In step (2), the extrusion temperatures of the twin-screw extruder are as follows: the first section is 180°C, the second section is 175°C, the third section is 170°C, the fourth section is 165°C, and the fifth section is 160°C; the screw rotational speed is 10 r / min.

9. The preparation method according to claim 6, characterized in that: In step (3), the drying temperature is 60°C and the time is 1 h; during injection molding, the injection temperatures from the feed port to the discharge port are as follows: the first section temperature is 200°C, the second section temperature is 190°C, the third section temperature is 180°C, the fourth section temperature is 170°C, and the fifth section temperature is 160°C; the injection pressure is 135 MPa and the holding pressure is 40 MPa.

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