High-property polypropylene composite material and preparation method thereof

Abstract

The application discloses a high-property polypropylene composite material and a preparation method thereof, relates to the technical field of polymer composite materials, and comprises the following components in parts by weight: 50-80 parts of a polypropylene matrix, 10-25 parts of oriented graphene / hydroxyapatite composite whiskers, 5-15 parts of a POE-g-GMA / nano silicon nitride composite toughening compatilizer, 3-10 parts of a filler, 0.2-2 parts of a lubricant and 0.2-1 part of an antioxidant; wherein the oriented graphene / hydroxyapatite composite whiskers are grafted with a maleic anhydride-styrene copolymer. The application has the effects of synergistically improving rigidity, toughness and heat resistance by combining the oriented graphene / hydroxyapatite composite whiskers with the POE-g-GMA / nano silicon nitride composite toughening compatilizer, and grafting the maleic anhydride-styrene copolymer, and has the effects of low mechanical property attenuation rate after long-term high-temperature aging, and significantly improved processing fluidity and size stability.

Description

Technical Field

[0001] This application relates to the field of polymer composite materials technology, and in particular to a high-performance polypropylene composite material and its preparation method. Background Technology

[0002] Polypropylene (PP) is one of the most widely used general-purpose thermoplastics, possessing advantages such as low density, good chemical stability, easy processing, and low cost, and is widely used in various fields such as automobiles, electronics, and construction. As industries upgrade towards high-end and lightweight products, the inherent defects of pure polypropylene, such as low impact strength, brittleness at low temperatures, difficulty in balancing rigidity and toughness, and insufficient heat resistance, can no longer meet the stringent requirements of high-end applications. Therefore, the industry commonly employs composite modification technology to prepare high-property polypropylene composites to achieve synergistic improvements in mechanical, heat resistance, and processing properties.

[0003] In existing technologies, high-performance polypropylene composites use polypropylene as the core matrix. Specifically, the composition includes at least one of homopolymer polypropylene, copolymer polypropylene, or highly crystalline polypropylene (50-80 parts by weight) as the matrix, at least one of glass fiber, carbon fiber, or calcium sulfate whiskers (5-30 parts by weight) as the reinforcing material, synergistically comprising a toughening agent (2-20 parts by weight, composed of elastomer) and fillers (5-25 parts by weight). Simultaneously, by adding 0.2-2 parts of lubricant, 0.2-1 parts of antioxidant, and 2-10 parts of modifying agents, the mechanochemical properties of the high-performance polypropylene composites are synergistically improved.

[0004] However, existing high-property-value polypropylene composites are difficult to adapt to the needs of high-end applications. Adding reinforcing materials leads to a decrease in toughness, and excessive addition of toughening agents reduces rigidity and heat resistance. In use, its heat distortion temperature is generally below 150℃, and it is prone to heat aging and mechanical property degradation under long-term high temperatures, which needs to be improved. Summary of the Invention

[0005] In view of this, the first objective of this application is to provide a high-performance polypropylene composite material to synergistically improve rigidity and heat resistance, thereby meeting the needs of high-end applications. The specific solution is as follows: A high-performance polypropylene composite material comprises 50-80 parts by weight of polypropylene matrix, 10-25 parts by weight of oriented graphene / hydroxyapatite composite whiskers, 5-15 parts by weight of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer, 3-10 parts by weight of filler, 0.2-2 parts by weight of lubricant, and 0.2-1 parts by weight of antioxidant; wherein the oriented graphene / hydroxyapatite composite whiskers are grafted with maleic anhydride-styrene copolymer.

[0006] Preferably, the polypropylene matrix is ​​one or more of homopolymer polypropylene, copolymer polypropylene, or highly crystalline polypropylene, mixed in any ratio.

[0007] Preferably, the preparation method of the oriented graphene / hydroxyapatite composite whiskers includes step ① adding 80-90 parts by weight of hydroxyapatite whisker precursor, 100-150 parts by weight of deionized water, and 0.5-1.5 parts by weight of dispersant into a hydrothermal reactor. The reactor is then subjected to controlled temperature of 160-180℃, pressure of 0.3-0.5MPa, and aspect ratio of 30-50:1, and the reaction is maintained at this temperature for 8-12 hours. Afterwards, the mixture is cooled, centrifuged, and dried to obtain oriented hydroxyapatite whiskers; step ② combining the oriented hydroxyapatite whiskers obtained in step ① with 5- 12 parts of maleic anhydride-styrene copolymer, 3-8 parts of graphene, and 2-5 parts of nano-silicon nitride particles are dispersed at high speed, with the rotation speed controlled at 1500-2000 r / min and the temperature at 60-80℃, for 30-60 min to obtain a pre-dispersion system; Step ③, 5-12 parts by weight of maleic anhydride-styrene copolymer are mixed with the pre-dispersion system for grafting to obtain a grafting reaction system, which is then washed, dried, and pulverized to obtain oriented graphene / hydroxyapatite composite whiskers with a grafting rate of 5-12% of maleic anhydride-styrene copolymer.

[0008] Preferably, in step ③, the mixed grafting involves adding 0.4-0.9 parts of di-tert-butyl peroxide to the pre-dispersed system, stirring for 15-20 minutes, adding maleic anhydride-styrene copolymer, heating to 120-140°C, and holding the reaction at that temperature for 5-7 hours to obtain the grafted reaction system.

[0009] Preferably, in step ③, the mixed grafting involves adding 0.2-0.7 parts of polyethylene glycol to the pre-dispersed system, stirring for 15-20 minutes, then adding maleic anhydride-styrene copolymer and heating to 120-140°C, maintaining the temperature for 5-7 hours to obtain the grafted reaction system.

[0010] Preferably, the dispersant is stearic acid, sodium dodecylbenzenesulfonate, polyethylene glycol, or sodium citrate.

[0011] Preferably, the preparation method of the POE-g-GMA / nano-silicon nitride composite toughening compatibilizer includes: Step 1, mixing 70-85 parts by weight of ethylene-octene copolymer at a controlled temperature of 160-180℃, a rotation speed of 30-50 r / min, and a melt plasticizing time of 5-8 min, then adding 8-15 parts of glycidyl acrylate and 0.8-1.5 parts of initiator, heating to 185-200℃ and holding for 10-15 min to obtain the POE-g-GMA active skeleton; Step 2, mixing 10-20 parts of nano-silicon nitride particles and 50-80 parts of... Ethanol and 20-30 parts of deionized water are mixed and ultrasonically dispersed for 20-30 minutes, with the ultrasonic power controlled at 300-500W, to obtain a sol system; Step 3: The POE-g-GMA active skeleton is added to the sol system, and the temperature is controlled at 70-90℃ and the stirring speed at 300-500r / min, and the reaction is maintained at this temperature for 2-4 hours. Finally, 1-3 parts of hindered phenolic heat-resistant additive are added and the reaction is stirred for 30-60 minutes to obtain the final reaction system; Step 4: The final reaction system is subjected to vacuum distillation, drying and granulation in sequence to obtain the POE-g-GMA / nano silicon nitride composite toughening compatibilizer.

[0012] Preferably, the initiator is benzoyl peroxide, azobisisobutyronitrile, or di-tert-butyl peroxide; the hindered phenolic heat-resistant additive is antioxidant 1010 or antioxidant 1076.

[0013] Preferably, the filler is ultrafine talc powder or ultrafine calcium carbonate with a particle size of 3000-10000 mesh; the lubricant is at least one of calcium stearate, EBS or erucamide; and the antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1-2.

[0014] The second objective of this invention is to provide a method for preparing a high-performance polypropylene composite material. This method, used to prepare the high-performance polypropylene composite material described above, includes the following steps: Step 1: Add the appropriate weight parts of polypropylene matrix, oriented graphene / hydroxyapatite composite whiskers, POE-g-GMA / nano silicon nitride composite toughening compatibilizer, filler, lubricant, and antioxidant to a high-speed mixer, control the rotation speed at 800-1200 r / min and the temperature at 80-100℃, stir for 3-5 min and obtain a mixture. Step 2: Feed the mixture into a twin-screw extruder, control the temperature of the feeding section to 180-190℃, the temperature of the melting section to 190-210℃, the temperature of the homogenization section to 200-220℃, the temperature of the die head to 210-220℃, and the screw speed to 350-450 r / min. After extrusion, cool with water and then pelletize to obtain high-property-value polypropylene composite material particles.

[0015] As can be seen from the above solutions, this application provides a high-performance polypropylene composite material and its preparation method, which has the following beneficial effects: 1. High rigidity is provided by directional graphene / hydroxyapatite composite whiskers, which are synergistically modified by grafting maleic anhydride-styrene copolymer and form a stable cross-linked network with POE-g-GMA / nano silicon nitride composite toughening compatibilizer. This effectively compensates for the brittleness while avoiding whisker agglomeration, and achieves a synergistic improvement in rigidity and toughness. 2. By combining the high-temperature resistance and thermal conductivity of oriented graphene / hydroxyapatite composite whiskers with the high-temperature resistance and anti-aging properties of POE-g-GMA / nano silicon nitride composite toughening compatibilizer, the high-temperature degradation of the material is inhibited. Furthermore, the interfacial bonding strength is improved by grafting maleic anhydride-styrene copolymer, which reduces interfacial peeling during high-temperature aging, thereby significantly improving the heat resistance and high-temperature stability. 3. By using maleic anhydride-styrene copolymer, the industrial production cost can be reduced, and the process is convenient and easy to scale up for industrial production. Detailed Implementation

[0016] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0017] It should be noted that the polypropylene matrix in this embodiment has a melt flow index of 10-30 g / 10 min at a test temperature of 230°C and an applied weight load of 2.16 kg. Meanwhile, the polypropylene matrix is ​​one or more of homopolymer polypropylene, copolymer polypropylene, or highly crystalline polypropylene mixed in any ratio. The filler is ultrafine talc powder or ultrafine calcium carbonate with a particle size of 3000-10000 mesh. The lubricant is at least one of calcium stearate, EBS, or erucamide. The antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1-2. Of course, in a specific embodiment of this application, the polypropylene matrix is ​​a mixture of homopolymer polypropylene and copolymer polypropylene in a mass ratio of 1:2. The filler is ultrafine talc powder with a particle size of 6000 mesh. The lubricant is calcium stearate. The antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.5.

[0018] The following will provide a detailed description of a high-performance polypropylene composite material and its preparation method.

[0019] A high-property-value polypropylene composite material includes 50-80 parts by weight of polypropylene matrix, 10-25 parts by weight of oriented graphene / hydroxyapatite composite whiskers, 5-15 parts by weight of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer, 3-10 parts by weight of filler, 0.2-2 parts by weight of lubricant, and 0.2-1 parts by weight of antioxidant.

[0020] It should be noted that the oriented graphene / hydroxyapatite composite whiskers are grafted with maleic anhydride-styrene copolymer. The preparation method of the oriented graphene / hydroxyapatite composite whiskers includes step ① adding 80-90 parts by weight of hydroxyapatite whisker precursor, 100-150 parts by weight of deionized water, and 0.5-1.5 parts by weight of stearic acid, sodium dodecylbenzene sulfonate, polyethylene glycol, or sodium citrate as a dispersant to a hydrothermal reactor. The temperature is controlled at 160-180℃, the pressure at 0.3-0.5 MPa, and the aspect ratio at 30-50:1. After reacting at this temperature for 8-12 hours, the mixture is successively cooled, centrifuged, and dried to obtain the oriented hydroxyapatite whiskers; step ②... Whiskers are dispersed at high speed with 5-12 parts by weight of maleic anhydride-styrene copolymer, 3-8 parts by weight of graphene, and 2-5 parts by weight of nano-silicon nitride particles. The speed is controlled at 1500-2000 r / min and the temperature at 60-80℃ for 30-60 min to obtain a pre-dispersion system. Step ③: 5-12 parts by weight of maleic anhydride-styrene copolymer are mixed with the pre-dispersion system to obtain a grafting reaction system. After washing, drying, and pulverizing, oriented graphene / hydroxyapatite composite whiskers with a grafting rate of 5-12% of maleic anhydride-styrene copolymer are obtained. In step ③, in order to improve the grafting effect of maleic anhydride-styrene copolymer and pre-dispersion system, the mixed grafting is carried out by adding 0.4-0.9 parts of di-tert-butyl peroxide to the pre-dispersion system and stirring for 15-20 min, then adding maleic anhydride-styrene copolymer and heating to 120-140℃, and holding the reaction for 5-7 h to obtain the grafted reaction system.

[0021] Meanwhile, the preparation method of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer includes the following steps: Step 1: 70-85 parts by weight of ethylene-octene copolymer are mixed at a controlled temperature of 160-180℃, a rotation speed of 30-50 r / min, and a melt plasticizing time of 5-8 min. Then, 8-15 parts by weight of glycidyl acrylate and 0.8-1.5 parts by weight of benzoyl peroxide, azobisisobutyronitrile, or di-tert-butyl peroxide are added as initiators, and the mixture is heated to 185-200℃ and held for 10-15 min to obtain the POE-g-GMA active framework; Step 2: 10-20 parts by weight of nano-silicon nitride particles, 50-8... Step 1: Mix 0 parts of ethanol with 20-30 parts of deionized water and ultrasonically disperse for 20-30 minutes, controlling the ultrasonic power at 300-500W to obtain a sol system; Step 2: Add the POE-g-GMA active framework to the sol system, control the temperature at 70-90℃ and the stirring speed at 300-500r / min, and keep the reaction at this temperature for 2-4 hours. Finally, add 1-3 parts of antioxidant 1010 or antioxidant 1076 as a hindered phenolic heat-resistant additive and stir the reaction for 30-60 minutes to obtain the final reaction system; Step 3: Sequentially subject the final reaction system to vacuum distillation, drying, and granulation to obtain the POE-g-GMA / nano silicon nitride composite toughening compatibilizer.

[0022] A method for preparing a high-performance polypropylene composite material, comprising the following steps: Step 1: Add the appropriate weight parts of polypropylene matrix, oriented graphene / hydroxyapatite composite whiskers, POE-g-GMA / nano silicon nitride composite toughening compatibilizer, filler, lubricant, and antioxidant to a high-speed mixer, control the rotation speed at 800-1200 r / min and the temperature at 80-100℃, stir for 3-5 min and obtain a mixture. Step 2: Feed the mixture into a twin-screw extruder, control the temperature of the feeding section to 180-190℃, the temperature of the melting section to 190-210℃, the temperature of the homogenization section to 200-220℃, the temperature of the die head to 210-220℃, and the screw speed to 350-450 r / min. After extrusion, cool with water and then pelletize to obtain high-property-value polypropylene composite material particles.

[0023] Example 1 A high-performance polypropylene composite material comprises 50 parts by weight of polypropylene matrix, 10 parts by weight of oriented graphene / hydroxyapatite composite whiskers, 5 parts by weight of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer, 3 parts by weight of filler, 0.2 parts by weight of lubricant and 0.2 parts by weight of antioxidant.

[0024] It should be noted that the oriented graphene / hydroxyapatite composite whiskers are grafted with maleic anhydride-styrene copolymer. The preparation method of the oriented graphene / hydroxyapatite composite whiskers includes step ① adding 80 parts by weight of hydroxyapatite whisker precursor, 100 parts by weight of deionized water, and 0.5 parts by weight of stearic acid to a hydrothermal reactor. The temperature is controlled at 160℃, the pressure at 0.3MPa, and the aspect ratio at 30:1. After reacting at this temperature for 8 hours, the mixture is successively cooled, centrifuged, and dried to obtain oriented hydroxyapatite whiskers; step ② combining the oriented hydroxyapatite whiskers obtained in step ① with 5 parts by weight of... Maleic anhydride-styrene copolymer, 3 parts graphene, and 2 parts nano-silicon nitride particles were dispersed at high speed at a speed of 1500 r / min and a temperature of 60℃ for 60 min to obtain a pre-dispersion system. Step ③: 5 parts by weight of maleic anhydride-styrene copolymer were mixed with the pre-dispersion system for grafting to obtain a grafting reactant system. After washing, drying, and pulverizing, oriented graphene / hydroxyapatite composite whiskers grafted with maleic anhydride-styrene copolymer were obtained. In step ③, to improve the grafting effect between the maleic anhydride-styrene copolymer and the pre-dispersion system, the mixed grafting involved adding 0.4 parts of di-tert-butyl peroxide to the pre-dispersion system and stirring for 15 min, followed by adding the maleic anhydride-styrene copolymer and heating to 120℃ for 7 h to obtain the grafting reactant system.

[0025] Meanwhile, the preparation method of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer includes the following steps: Step 1: 70 parts by weight of ethylene-octene copolymer are subjected to intensive mixing at a controlled temperature of 160℃, a rotation speed of 30 r / min, and a melt plasticizing time of 8 min. Then, 8 parts of glycidyl acrylate and 0.8 parts of benzoyl peroxide are added as initiators, and the mixture is heated to 185℃ and held for 15 min to obtain the POE-g-GMA active framework; Step 2: 10 parts of nano-silicon nitride particles, 50 parts of ethanol, and 20... Step 1: Mix 1 part of deionized water and ultrasonically disperse for 20 min, controlling the ultrasonic power at 300W to obtain a sol system; Step 2: Add the POE-g-GMA active skeleton to the sol system, control the temperature at 70℃ and the stirring speed at 300 r / min, and keep the reaction at this temperature for 4 h. Finally, add 1 part of antioxidant 1010 as a hindered phenolic heat-resistant additive and stir for 30 min to obtain the final reaction system; Step 3: Pass the final reaction system through vacuum distillation, drying and granulation in sequence to obtain the POE-g-GMA / nano silicon nitride composite toughening compatibilizer.

[0026] A method for preparing a high-performance polypropylene composite material, comprising the following steps: Step 1: Add the appropriate weight parts of polypropylene matrix, oriented graphene / hydroxyapatite composite whiskers, POE-g-GMA / nano silicon nitride composite toughening compatibilizer, filler, lubricant, and antioxidant to a high-speed mixer, control the speed at 800 r / min and the temperature at 80℃, stir for 5 min and obtain the mixture. Step 2: Feed the mixture into a twin-screw extruder, control the temperature of the feeding section to 180℃, the temperature of the melting section to 190℃, the temperature of the homogenization section to 200℃, the temperature of the die head to 210℃, and the screw speed to 350 r / min. After extrusion, cool with water and then pelletize to obtain high-property-value polypropylene composite particles.

[0027] Example 2 A high-performance polypropylene composite material comprises 65 parts by weight of polypropylene matrix, 16 parts by weight of oriented graphene / hydroxyapatite composite whiskers, 10 parts by weight of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer, 6 parts by weight of filler, 1 part by weight of lubricant and 0.6 parts by weight of antioxidant.

[0028] It should be noted that the oriented graphene / hydroxyapatite composite whiskers are grafted with maleic anhydride-styrene copolymer. The preparation method of the oriented graphene / hydroxyapatite composite whiskers includes step ① adding 85 parts by weight of hydroxyapatite whisker precursor, 120 parts by weight of deionized water, and 1 part by weight of polyethylene glycol as a dispersant to a hydrothermal reactor. The temperature is controlled at 170℃, the pressure at 0.4 MPa, and the aspect ratio at 40:1. After reacting at this temperature for 10 hours, the mixture is successively cooled, centrifuged, and dried to obtain oriented hydroxyapatite whiskers; step ② combining the oriented hydroxyapatite whiskers obtained in step ① with... Eight parts by weight of maleic anhydride-styrene copolymer, five parts by weight of graphene, and three parts by weight of nano-silicon nitride particles were dispersed at high speed at a speed of 1800 r / min and a temperature of 70℃ for 45 min to obtain a pre-dispersion system. In step ③, eight parts by weight of maleic anhydride-styrene copolymer were mixed with the pre-dispersion system for grafting to obtain a grafting reactant system. After washing, drying, and pulverizing, oriented graphene / hydroxyapatite composite whiskers grafted with maleic anhydride-styrene copolymer were obtained. In step ③, to improve the grafting effect between the maleic anhydride-styrene copolymer and the pre-dispersion system, the mixed grafting involved adding 0.7 parts by weight of di-tert-butyl peroxide to the pre-dispersion system and stirring for 18 min, followed by adding the maleic anhydride-styrene copolymer and heating to 130℃ for 6 h to obtain the grafting reactant system.

[0029] Meanwhile, the preparation method of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer includes the following steps: Step 1: 80 parts by weight of ethylene-octene copolymer are subjected to intensive mixing at a controlled temperature of 170℃, a rotation speed of 40 r / min, and a melt plasticizing time of 6 min. Then, 12 parts by weight of glycidyl acrylate and 1.1 parts by weight of azobisisobutyronitrile are added as initiators, and the mixture is heated to 190℃ and held for 12 min to obtain the POE-g-GMA active framework; Step 2: 15 parts by weight of nano-silicon nitride particles, 65 parts by weight of ethanol, and 25 parts by weight of... Step 1: Mix 1 part of deionized water and ultrasonically disperse for 25 min, controlling the ultrasonic power at 400W to obtain a sol system; Step 2: Add the POE-g-GMA active skeleton to the sol system, control the temperature at 80℃ and the stirring speed at 400 r / min, and keep the reaction at this temperature for 3 h. Finally, add 2 parts of antioxidant 1076 as a hindered phenolic heat-resistant additive and stir for 45 min to obtain the final reaction system; Step 3: Pass the final reaction system through vacuum distillation, drying and granulation to obtain the POE-g-GMA / nano silicon nitride composite toughening compatibilizer.

[0030] A method for preparing a high-performance polypropylene composite material, comprising the following steps: Step 1: Add the appropriate weight parts of polypropylene matrix, oriented graphene / hydroxyapatite composite whiskers, POE-g-GMA / nano silicon nitride composite toughening compatibilizer, filler, lubricant, and antioxidant to a high-speed mixer, control the speed at 1000 r / min and the temperature at 90℃, stir for 4 min and obtain the mixture. Step 2: Feed the mixture into a twin-screw extruder, control the temperature of the feeding section to 185℃, the temperature of the melting section to 200℃, the temperature of the homogenization section to 210℃, the temperature of the die head to 215℃, and the screw speed to 400r / min. After extrusion, cool with water and then pelletize to obtain high-property-value polypropylene composite particles.

[0031] Example 3 A high-performance polypropylene composite material comprises 80 parts by weight of polypropylene matrix, 25 parts by weight of oriented graphene / hydroxyapatite composite whiskers, 15 parts by weight of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer, 10 parts by weight of filler, 2 parts by weight of lubricant and 1 part by weight of antioxidant.

[0032] It should be noted that the oriented graphene / hydroxyapatite composite whiskers are grafted with maleic anhydride-styrene copolymer. The preparation method of the oriented graphene / hydroxyapatite composite whiskers includes step ① adding 90 parts by weight of hydroxyapatite whisker precursor, 150 parts by weight of deionized water, and 1.5 parts by weight of sodium dodecylbenzenesulfonate as a dispersant to a hydrothermal reactor. The temperature is controlled at 180℃, the pressure at 0.5MPa, and the aspect ratio at 50:1. After reacting at this temperature for 8-12 hours, the mixture is successively cooled, centrifuged, and dried to obtain oriented hydroxyapatite whiskers; step ② combining the oriented hydroxyapatite whiskers obtained in step ① with... A pre-dispersed system was obtained by high-speed dispersion of 12 parts by weight of maleic anhydride-styrene copolymer, 8 parts by weight of graphene, and 5 parts by weight of nano-silicon nitride particles at a controlled rotation speed of 2000 r / min and a temperature of 80℃ for 30 min. Step ③ involved mixing 12 parts by weight of maleic anhydride-styrene copolymer with the pre-dispersed system to obtain a grafting reaction system. This system was then washed, dried, and pulverized to obtain oriented graphene / hydroxyapatite composite whiskers grafted with maleic anhydride-styrene copolymer. In step ③, to improve the grafting effect between the maleic anhydride-styrene copolymer and the pre-dispersed system, the mixed grafting involved adding 0.9 parts by weight of di-tert-butyl peroxide to the pre-dispersed system and stirring for 20 min, followed by adding the maleic anhydride-styrene copolymer and heating to 140℃ for 5 h to obtain the grafting reaction system.

[0033] Meanwhile, the preparation method of POE-g-GMA / nano-silicon nitride composite toughening compatibilizer includes the following steps: Step 1: 85 parts by weight of ethylene-octene copolymer are subjected to intensive mixing at a controlled temperature of 180℃, a rotation speed of 50 r / min, and a melt plasticizing time of 5 min. Then, 15 parts by weight of glycidyl acrylate and 1.5 parts by weight of di-tert-butyl peroxide are added as initiators, and the mixture is heated to 200℃ and held for 10 min to obtain the POE-g-GMA active framework; Step 2: 20 parts by weight of nano-silicon nitride particles, 80 parts by weight of ethanol, and 3... Step 1: Mix 0 parts of deionized water and ultrasonically disperse for 20 min, controlling the ultrasonic power at 500W to obtain a sol system; Step 2: Add the POE-g-GMA active skeleton to the sol system, control the temperature at 90℃ and the stirring speed at 500 r / min, and keep the reaction at this temperature for 2 h. Finally, add 3 parts of antioxidant 1010 as a hindered phenolic heat-resistant additive and stir for 30 min to obtain the final reaction system; Step 3: Sequentially subject the final reaction system to vacuum distillation, drying and granulation to obtain the POE-g-GMA / nano silicon nitride composite toughening compatibilizer.

[0034] A method for preparing a high-performance polypropylene composite material, comprising the following steps: Step 1: Add the appropriate weight parts of polypropylene matrix, oriented graphene / hydroxyapatite composite whiskers, POE-g-GMA / nano silicon nitride composite toughening compatibilizer, filler, lubricant, and antioxidant to a high-speed mixer, control the speed at 1200 r / min and the temperature at 100℃, stir for 3 min and obtain a mixture. Step 2: Feed the mixture into a twin-screw extruder, control the temperature of the feeding section to 190℃, the temperature of the melting section to 210℃, the temperature of the homogenization section to 220℃, the temperature of the die head to 220℃, and the screw speed to 450 r / min. After extrusion, cool with water and then pelletize to obtain high-property-value polypropylene composite particles.

[0035] Example 4 The difference between Example 4 and Example 3 is that in Example 4, in step ③ of the preparation method of oriented graphene / hydroxyapatite composite whiskers, the mixing and grafting involves adding 0.2 parts of polyethylene glycol to the pre-dispersion system and stirring for 15 minutes before adding maleic anhydride-styrene copolymer.

[0036] Example 5 The difference between Example 4 and Example 3 is that in Example 4, in step ③ of the preparation method of oriented graphene / hydroxyapatite composite whiskers, the mixing and grafting involves adding 0.5 parts of polyethylene glycol to the pre-dispersion system and stirring for 18 minutes before adding maleic anhydride-styrene copolymer.

[0037] Example 6 The difference between Example 4 and Example 3 is that in Example 4, in step ③ of the preparation method of oriented graphene / hydroxyapatite composite whiskers, the mixing and grafting involves adding 0.7 parts of polyethylene glycol to the pre-dispersion system and stirring for 20 minutes before adding maleic anhydride-styrene copolymer.

[0038] Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that the oriented graphene / hydroxyapatite composite whiskers in Comparative Example 1 were not grafted with maleic anhydride-styrene copolymer.

[0039] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that in step ③ of the preparation method of oriented graphene / hydroxyapatite composite whiskers in Comparative Example 2, di-tert-butyl peroxide was not added.

[0040] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that in Comparative Example 3, maleic anhydride-grafted ethylene-octene copolymer was used instead of POE-g-GMA / nano silicon nitride composite toughening compatibilizer.

[0041] Performance testing: 1. Set the sample size to 80mm × 10mm × 4mm; 2. Density test: The density of the sample was obtained by testing according to GB / T1033.1-2008 "Determination of density of non-foamed plastics - Part 1: Immersion method, liquid specific gravity bottle method and titration method (Method A)"; 2. Flexural modulus test: According to GB / T9341-2008 "Determination of Flexural Properties of Plastics", the test temperature was set to 23℃, the span was 64mm, the loading speed was 2mm / min, and 5 samples were tested in each group, and the average value was taken. 3. Notched impact strength test: According to GB / T1843-2008 "Determination of notched impact strength of plastic cantilever beam", the test temperature was set at 23℃ and the impact speed was 3.5m / s. Five samples were tested in each group and the average value was taken. 4. Heat distortion temperature test: According to GB / T 17037.4 "Preparation of injection molded specimens of thermoplastic materials - Part 4: Determination of molding shrinkage", the molding shrinkage rate was obtained by testing. 5. -30℃ Multiaxial Impact Test: The test was conducted according to GB / T14152-2001 Test Method for Resistance to External Impact of Thermoplastic Pipes by Clockwise Rotation Method to obtain the equivalent evaluation of low-temperature multiaxial impact.

[0042] The performance test results are shown in Table 1 below.

[0043] Table 1 Performance Test Results

[0044] As shown in Table 1 above, in Examples 1 to 3, the polypropylene matrix, oriented graphene / hydroxyapatite composite whiskers, POE-g-GMA / nano silicon nitride composite toughening compatibilizer and filler in Example 3 are added in synergistic amounts to form a rigid support and interface bonding system that is superior to other examples. As a result, it has the best flexural modulus and the lowest molding shrinkage, indicating that it has the best dimensional stability. At the same time, it maintains good notched impact strength and low-temperature toughness, and its overall physical properties are the most outstanding.

[0045] In Example 4, based on the use of polyethylene glycol-mediated grafting, the interfacial compatibility between the oriented graphene / hydroxyapatite composite whiskers and the matrix is ​​optimized to form a stable bridging structure, effectively reducing filler agglomeration. As a result, it has physicochemical properties similar to those of Examples 1 to 3. Its density, flexural modulus, notched impact strength and molding shrinkage are all between those of Examples 2 and 3. Low-temperature multiaxial impact also shows ductile fracture, and the overall performance is stable and excellent.

[0046] In Comparative Example 1, the absence of maleic anhydride-styrene copolymer meant that no cross-linked network structure was formed between it and the POE-g-GMA / nano-silicon nitride composite toughening compatibilizer. This resulted in poor component compatibility and significant whisker agglomeration, leading to a significant increase in the density of the high-property polypropylene composite material, a substantial decrease in flexural modulus and notched impact strength, a significant weakening of rigidity and toughness, a significant increase in molding shrinkage, poor dimensional stability, and brittle fracture under multiaxial impact at -30°C. Furthermore, the heat resistance and low-temperature toughness were comprehensively deteriorated.

[0047] In Comparative Example 2, the absence of di-tert-butyl peroxide resulted in the inactivation of hydroxyl groups on the surface of the oriented graphene / hydroxyapatite composite whiskers, uneven grafting of the maleic anhydride-styrene copolymer, weakened interfacial bonding strength, and a significant decrease in performance. Its density was higher than that of Examples 1 to 4, while its flexural modulus and notched impact strength were lower. The molding shrinkage was also higher, and it exhibited quasi-ductile fracture in a multiaxial impact test at -30°C. Overall, its performance was between that of Examples 1 and Comparative Example 1, indicating that the initiator had a significant effect on grafting and material properties.

[0048] Comparative Example 3, by using maleic anhydride-grafted ethylene-octene copolymer to replace the POE-g-GMA / nano-silicon nitride composite toughening compatibilizer, no longer possesses the rigid support and heat resistance synergistic effect of nano-silicon nitride particles, resulting in a decrease in its high-temperature resistance and anti-aging properties. It does not have the effect of synergistically promoting the improvement of heat distortion temperature, impact strength and anti-aging properties with oriented graphene / hydroxyapatite composite whiskers. Although its notched impact strength is higher than that of Comparative Example 1 and Comparative Example 2, it is lower than that of all examples. Its density is relatively high, and its molding shrinkage rate is close to that of the examples. However, its overall rigidity, heat resistance and long-term use stability are not as good as those of the examples.

[0049] In summary, this application provides a high-performance polypropylene composite material and its preparation method. Firstly, the high rigidity of this high-performance polypropylene composite material and its preparation method is achieved through oriented graphene / hydroxyapatite composite whiskers, synergistically modified with maleic anhydride-styrene copolymer, and formed with a POE-g-GMA / nano-silicon nitride composite toughening compatibilizer to form a stable cross-linked network. This effectively compensates for brittleness while preventing whisker agglomeration, achieving a synergistic improvement in rigidity and toughness. Secondly, the high-temperature resistance and thermal conductivity of the oriented graphene / hydroxyapatite composite whiskers, combined with the high-temperature resistance and anti-aging effects of the POE-g-GMA / nano-silicon nitride composite toughening compatibilizer, synergistically inhibit high-temperature degradation of the material. Furthermore, the grafting with maleic anhydride-styrene copolymer enhances the interfacial bonding strength, reducing interfacial delamination during high-temperature aging, thus significantly improving heat resistance and high-temperature stability. Simultaneously, the high-performance polypropylene composite material and its preparation method of this application reduce industrial production costs by using maleic anhydride-styrene copolymer, and the process is convenient and easy for large-scale industrial production.

[0050] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.

[0051] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0052] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A high-performance polypropylene composite material, characterized in that: The product comprises 50-80 parts by weight of polypropylene matrix, 10-25 parts of oriented graphene / hydroxyapatite composite whiskers, 5-15 parts of POE-g-GMA / nano silicon nitride composite toughening compatibilizer, 3-10 parts of filler, 0.2-2 parts of lubricant, and 0.2-1 parts of antioxidant; wherein the oriented graphene / hydroxyapatite composite whiskers are grafted with maleic anhydride-styrene copolymer.

2. The high-property polypropylene composite material according to claim 1, characterized in that: The polypropylene matrix is ​​one or more of homopolymer polypropylene, copolymer polypropylene, or highly crystalline polypropylene, mixed in any ratio.

3. The high-property polypropylene composite material according to claim 1, characterized in that: The preparation method of the oriented graphene / hydroxyapatite composite whiskers includes step ① adding 80-90 parts by weight of hydroxyapatite whisker precursor, 100-150 parts by weight of deionized water, and 0.5-1.5 parts by weight of dispersant into a hydrothermal reactor. The reactor is kept at a controlled temperature of 160-180℃, a pressure of 0.3-0.5 MPa, and an aspect ratio of 30-50:1 for 8-12 hours. After cooling, centrifugation, and drying, oriented hydroxyapatite whiskers are obtained. Step ② combining the oriented hydroxyapatite whiskers obtained in step ① with 5-12 parts by weight of... A pre-dispersion system is obtained by high-speed dispersion of maleic anhydride-styrene copolymer, 3-8 parts graphene, and 2-5 parts nano-silicon nitride particles, with the rotation speed controlled at 1500-2000 r / min and the temperature at 60-80℃ for 30-60 min; Step ③: 5-12 parts by weight of maleic anhydride-styrene copolymer are mixed with the pre-dispersion system to obtain a grafting reaction system, which is then washed, dried, and pulverized to obtain oriented graphene / hydroxyapatite composite whiskers with a grafting rate of 5-12% of maleic anhydride-styrene copolymer.

4. The high-property polypropylene composite material according to claim 3, characterized in that: In step ③, the mixed grafting involves adding 0.4-0.9 parts of di-tert-butyl peroxide to the pre-dispersed system, stirring for 15-20 minutes, adding maleic anhydride-styrene copolymer, heating to 120-140°C, and holding the reaction at that temperature for 5-7 hours to obtain the grafted reaction system.

5. A high-property polypropylene composite material according to claim 3, characterized in that: In step ③, the mixed grafting involves adding 0.2-0.7 parts of polyethylene glycol to the pre-dispersed system, stirring for 15-20 minutes, adding maleic anhydride-styrene copolymer, heating to 120-140°C, and holding the reaction at that temperature for 5-7 hours to obtain the grafted reaction system.

6. The high-property polypropylene composite material according to claim 3, characterized in that: The dispersant is stearic acid, sodium dodecylbenzenesulfonate, polyethylene glycol, or sodium citrate.

7. The high-property polypropylene composite material according to claim 1, characterized in that: The preparation method of the POE-g-GMA / nano-silicon nitride composite toughening compatibilizer includes the following steps: Step 1: 70-85 parts by weight of ethylene-octene copolymer are subjected to intensive mixing at a controlled temperature of 160-180℃, a rotation speed of 30-50 r / min, and a melt plasticizing time of 5-8 min. Then, 8-15 parts of glycidyl acrylate and 0.8-1.5 parts of initiator are added, and the mixture is heated to 185-200℃ and held for 10-15 min to obtain the POE-g-GMA active framework. Step 2: 10-20 parts of nano-silicon nitride particles and 50-80 parts of ethanol are mixed. Step 1: Mix with 20-30 parts of deionized water and ultrasonically disperse for 20-30 minutes, controlling the ultrasonic power at 300-500W to obtain a sol system; Step 2: Add the POE-g-GMA active skeleton to the sol system, control the temperature at 70-90℃ and the stirring speed at 300-500r / min, and keep the reaction at this temperature for 2-4 hours. Finally, add 1-3 parts of hindered phenolic heat-resistant additive and stir for 30-60 minutes to obtain the final reaction system; Step 3: Sequentially subject the final reaction system to vacuum distillation, drying and granulation to obtain the POE-g-GMA / nano silicon nitride composite toughening compatibilizer.

8. A high-property polypropylene composite material according to claim 7, characterized in that: The initiator is benzoyl peroxide, azobisisobutyronitrile, or di-tert-butyl peroxide; the hindered phenolic heat-resistant additive is antioxidant 1010 or antioxidant 1076.

9. A high-property polypropylene composite material according to claim 1, characterized in that: The filler is ultrafine talc or ultrafine calcium carbonate with a particle size of 3000-10000 mesh; the lubricant is at least one of calcium stearate, EBS or erucamide; the antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1-2.

10. A method for preparing a high-performance polypropylene composite material, used to prepare a high-performance polypropylene composite material as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Add the appropriate weight parts of polypropylene matrix, oriented graphene / hydroxyapatite composite whiskers, POE-g-GMA / nano silicon nitride composite toughening compatibilizer, filler, lubricant, and antioxidant to a high-speed mixer, control the rotation speed at 800-1200 r / min and the temperature at 80-100℃, stir for 3-5 min and obtain a mixture. Step 2: Feed the mixture into a twin-screw extruder, control the temperature of the feeding section to 180-190℃, the temperature of the melting section to 190-210℃, the temperature of the homogenization section to 200-220℃, the temperature of the die head to 210-220℃, and the screw speed to 350-450 r / min. After extrusion, cool with water and then pelletize to obtain high-property-value polypropylene composite material particles.

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