Bamboo fiber modified reinforced polypropylene composite material and preparation method thereof

Abstract

The application relates to the technical field of high-performance polypropylene, and discloses a bamboo fiber modified reinforced polypropylene composite material and a preparation method thereof, which comprises the following raw materials in parts by mass: functionalized polypropylene 60-80 parts, modified bamboo fiber 15-35 parts, activated calcium carbonate 5-15 parts, a compatilizer 4-8 parts, an antioxidant 0.5-1.5 parts, and a lubricant 0.3-0.8 parts. The composite material prepared by the application has excellent mechanical properties, antistatic properties and flame-retardant properties, the raw materials are widely sourced and the cost is controllable, the preparation process is mild and easy to operate, the performance improvement and industrial production feasibility are considered, the composite material can be widely applied to multiple fields such as automobile interiors, electronic and electrical appliance shells and building materials, and has remarkable practical value and market prospect.

Description

Technical Field

[0001] This invention relates to the field of high-performance polypropylene technology, specifically to bamboo fiber modified and reinforced polypropylene composite materials and their preparation methods. Background Technology

[0002] Polypropylene, as one of the five major general-purpose plastics, boasts advantages such as low density, good chemical resistance, easy processing and molding, and low cost, making it widely used in the automotive industry, electronics, building materials, and daily consumer goods. However, pure polypropylene also has significant performance limitations. Its antistatic properties are poor, and it easily accumulates static charge due to friction during use, which not only attracts dust and affects the appearance of products but may also cause electrostatic discharge. Furthermore, its mechanical strength needs improvement under certain operating conditions. In addition, polypropylene is a flammable material, which limits its application in fields requiring high flame retardancy, such as electronic appliance housings, automotive interior parts, and building materials. Therefore, developing a method to improve the mechanical strength, antistatic properties, and flame retardancy of polypropylene materials has significant application value and practical importance. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a bamboo fiber modified and reinforced polypropylene composite material and its preparation method.

[0004] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, a bamboo fiber-modified reinforced polypropylene composite material comprises the following raw materials in parts by weight: Functionalized polypropylene 60-80 parts, modified bamboo fiber 15-35 parts, activated calcium carbonate 5-15 parts, compatibilizer 4-8 parts, antioxidant 0.5-1.5 parts, lubricant 0.3-0.8 parts; The compatibilizer is prepared by compounding maleic anhydride-grafted polypropylene and citric acid in a mass ratio of 3:0.5~1. The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:0.5~1; The lubricant is a compound of calcium stearate and polyethylene wax in a mass ratio of 2:1 to 1.5.

[0005] Furthermore, the preparation method of reinforced polypropylene includes the following steps: A1. Place 100-120 parts of polypropylene in a vacuum drying oven at 80-90℃ and dry for 4-6 hours. After cooling, transfer them to a plasma treatment device and bombard them with argon gas for 3-5 minutes at a power of 300-400 W and a vacuum degree of 0.05-0.06 MPa. A2. Add the plasma-treated polypropylene, 8-10 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 4-5 parts of sodium hydroxide, 3-4 parts of glycidyl methacrylate, 2-3 parts of cysteine ​​hydrochloride, 1-1.5 parts of hexamethylene diisocyanate, 0.5-1 part of styrene, and 0.5-0.8 parts of divinylbenzene to a high-speed mixer in sequence, then add 0.6-0.8 parts of dicumyl peroxide, and stir at 300-500 r / min for 20-25 min to form a mixture; A3. Add the mixture to a twin-screw extruder with a length-to-diameter ratio of 30~40:1, temperature gradient: zone 1 140~150℃, zone 2 155~165℃, zone 3 170~180℃, zone 4 180~190℃, screw speed 230~260 r / min, material residence time 8~10min, and extruded strips are water-cooled at 15~25℃ and vacuum-dried at 60~80℃ for 6~8 h to obtain functionalized polypropylene.

[0006] Furthermore, the preparation method of modified bamboo fiber includes the following steps: B1. Add 100-120 parts of activated bamboo fiber, 15-20 parts of succinic anhydride, 5-8 parts of pyridine, and 300-500 parts of ethanol to a round-bottom flask, heat to reflux, and stir at a constant temperature for 2-3 hours. After the reaction is complete, wash with deionized water 2-3 times and dry under vacuum at 60-80℃ for 6-8 hours to obtain carboxylated bamboo fiber. B2. Immerse 80-90 parts of carboxylated bamboo fiber in a 3-5% (w / w) aqueous solution of zinc chloride containing metal ions, and disperse with ultrasonic assistance at a power of 200-300 W and a frequency of 30-40 kHz for 20-30 min. Stir and react at room temperature for 1.5-2 h, filter to separate the fiber, wash with deionized water 3-5 times, and vacuum dry at 60-80℃ for 6-8 h to obtain zinc ion complexed bamboo fiber. B3. Add 60-80 parts of zinc ion complexed bamboo fiber and 10-15 parts of ammonium polyphosphate to a high-speed mixer, add 400-500 parts of deionized water, stir and mix at 60-80℃ for 15-30 min, transfer to a 100-110℃ forced-air drying oven, dry for 1-2 h, cool to room temperature, pulverize, and pass through a 100-150 mesh sieve to obtain modified bamboo fiber.

[0007] Further, the preparation method of activated bamboo fiber in step B1 is as follows: Take 150~200 parts of bamboo fiber and place it in 800~1200 parts of 0.5~2% sodium hydroxide solution, boil at 60~80℃ for 0.5~2 h, take it out and wash it repeatedly with deionized water until neutral, transfer it to a freeze dryer at -40~-50℃ and dry it for 40~50 h to obtain activated bamboo fiber.

[0008] Furthermore, in step B3, before adding the zinc ion-complexed bamboo fiber to the high-speed mixer, it is placed in a plasma treatment device and bombarded with oxygen plasma for 2-3 minutes at a power of 250-300 W and a vacuum degree of 0.05-0.06 MPa.

[0009] Furthermore, the method for preparing activated calcium carbonate includes the following steps: C1. Place 80-100 parts of calcium carbonate powder in a 100-110℃ forced-air drying oven and dry for 2-3 hours. Cool to room temperature, then add 3-5 parts of sodium citrate and 600-800 parts of deionized water to a three-necked flask, stir and disperse to form a suspension, and adjust the pH to 6.5-7.0 with dilute hydrochloric acid. C2. Place the three-necked flask in a constant temperature water bath and keep it at 70~80℃ with stirring for 1.5~2 h. After the reaction is complete, centrifuge the suspension at 2000~3000 r / min for 8~10 min. Wash the precipitate with deionized water 1~3 times, and then dry it in a vacuum drying oven at 80~100℃ for 2~4 h. Grind it through a 100~200 mesh sieve to obtain activated calcium carbonate.

[0010] Furthermore, during step C2, 0.5 to 1.5 parts of γ-aminopropyltriethoxysilane are added to the three-necked flask while maintaining the temperature and stirring.

[0011] A second aspect of the present invention provides a bamboo fiber-modified reinforced polypropylene composite material, comprising the following steps: S1. Add functionalized polypropylene and compatibilizer to a high-speed mixer and stir at 80~100℃ for 3~5 min. Add modified bamboo fiber and activated calcium carbonate and stir for 3~5 min. Add antioxidant and lubricant and stir for 2~3 min to form a premix. S2. Using a twin-screw extruder with a length-to-diameter ratio of 30~40:1, the premixed material is added to the feed hopper. The extrusion temperature gradient is: Zone 1 145~155℃, Zone 2 165~175℃, Zone 3 175~185℃, Zone 4 185~195℃, screw speed 240~260 r / min, material residence time 8~10 min, the extruded strip is cooled by a 15~25℃ water cooling device, and then pelletized by an underwater pelletizer to a diameter of 2~3 mm. The pellets are then transferred to a forced-air drying oven and dried at 80~100℃ for 4~6 h. After cooling to room temperature, the composite material is obtained.

[0012] (iii) Beneficial technical effects This invention provides a bamboo fiber-modified reinforced polypropylene composite material. After plasma activation, the functionalized polypropylene undergoes multi-site grafting to introduce cationic, epoxy, and mercapto groups, as well as hydroxyl and silane groups from activated calcium carbonate. This significantly enhances interfacial bonding, effectively suppresses bamboo fiber agglomeration and stress concentration, and results in a stable improvement in the composite material's mechanical strength. The modified bamboo fiber, through carboxylation, zinc ion complexation, and flame-retardant loading, establishes a stable conductive pathway, endowing the composite material with excellent antistatic properties. Simultaneously, it effectively inhibits the migration and loss of flame-retardant components, significantly improving the limiting oxygen index of the composite material.

[0013] The raw materials used in this invention are widely available and cost-controllable. The preparation process is mild and easy to operate, taking into account both performance improvement and feasibility for industrial production. The prepared composite material has excellent mechanical properties, antistatic properties and flame retardant properties, and can be widely used in many fields such as automotive interiors, electronic and electrical housings, and building materials, with significant practical value and market prospects. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0015] Unless otherwise specified, all components of the bamboo fiber modified and reinforced polypropylene composite material formulation of this invention are commercially available. All parts used in this invention are parts by weight; The polypropylene was purchased from Daqing Petrochemical Company; Cysteine ​​hydrochloride was purchased from Shandong Suihua Biotechnology Co., Ltd. Styrene was purchased from Daqing Petrochemical Company; The bamboo fiber was purchased from Hunan Zhuzhiyuan Environmental Protection Technology Co., Ltd. Maleic anhydride-grafted polypropylene: grafting rate 0.8~1.5%, purchased from Nanjing Deba Polymer Materials Co., Ltd.; Example 1, bamboo fiber modified and reinforced polypropylene composite material, comprising the following parts by weight of raw materials: Functionalized polypropylene 60 parts, modified bamboo fiber 15 parts, activated calcium carbonate 5 parts, compatibilizer 4 parts, antioxidant 0.5 parts, lubricant 0.3 parts; The compatibilizer is a mixture of maleic anhydride-grafted polypropylene and citric acid in a mass ratio of 3:0.5. The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:0.5; The lubricant is a compound of calcium stearate and polyethylene wax in a mass ratio of 2:1.

[0016] The preparation method of reinforced polypropylene includes the following steps: A1. Place 100 parts of polypropylene in an 80℃ vacuum drying oven and dry for 4 hours. After cooling, transfer them to a plasma treatment device and bombard them with argon gas for 3 minutes at a power of 300 W and a vacuum degree of 0.05 MPa. A2. The plasma-treated polypropylene, 8 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 4 parts of sodium hydroxide, 3 parts of glycidyl methacrylate, 2 parts of cysteine ​​hydrochloride, 1 part of hexamethylene diisocyanate, 0.5 parts of styrene, and 0.5 parts of divinylbenzene were sequentially added to a high-speed mixer, followed by 0.6 parts of dicumyl peroxide. The mixture was stirred at 300 r / min for 20 min to form a mixture. A3. Add the mixture to a twin-screw extruder with a length-to-diameter ratio of 30:1, temperature gradient: zone 1 140℃, zone 2 155℃, zone 3 170℃, zone 4 180℃, screw speed 230 r / min, material residence time 8 min, and extruded strip is water-cooled at 15℃ and vacuum-dried at 60℃ for 6 h to obtain functionalized polypropylene.

[0017] The preparation method of modified bamboo fiber includes the following steps: B1. Add 100 parts activated bamboo fiber, 15 parts succinic anhydride, 5 parts pyridine, and 300 parts ethanol to a round-bottom flask, heat to reflux, and stir at a constant temperature for 2 hours. After the reaction is complete, wash twice with deionized water and dry under vacuum at 60°C for 6 hours to obtain carboxylated bamboo fiber. B2. Immerse 80 parts of carboxylated bamboo fiber in a 3% (w / w) aqueous solution of zinc chloride containing metal ions, disperse with ultrasonic assistance at 200 W and 30 kHz for 20 min, stir at room temperature for 1.5 h, filter to separate the fiber, wash with deionized water 3 times, and vacuum dry at 60℃ for 6 h to obtain zinc ion complexed bamboo fiber. B3. Add 60 parts of zinc ion complexed bamboo fiber and 10 parts of ammonium polyphosphate to a high-speed mixer, add 400 parts of deionized water, stir and mix at 60°C for 15 min, transfer to a 100°C forced-air drying oven, dry for 1 h, cool to room temperature, pulverize, and pass through a 100-mesh sieve to obtain modified bamboo fiber.

[0018] The preparation method of activated bamboo fiber in step B1 is as follows: Take 150 parts of bamboo fiber and place it in 800 parts of 0.5% sodium hydroxide solution, boil at 60℃ for 0.5 h, take it out and wash it repeatedly with deionized water until neutral, transfer it to a freeze dryer at -40℃ and dry for 40 h to obtain activated bamboo fiber.

[0019] In step B3, before the zinc ion-complexed bamboo fiber is added to the high-speed mixer, it is placed in a plasma treatment device and bombarded with oxygen plasma for 2 minutes at a power of 250 W and a vacuum degree of 0.05 MPa.

[0020] The preparation method of activated calcium carbonate includes the following steps: C1. Place 80 parts of calcium carbonate powder in a 100℃ forced-air drying oven and dry for 2 hours. Cool to room temperature, then add 3 parts of sodium citrate and 600 parts of deionized water to a three-necked flask, stir and disperse to form a suspension, and adjust the pH to 6.5 with dilute hydrochloric acid. C2. Place the three-necked flask in a constant temperature water bath and keep it at 70℃ with stirring for 1.5 h. After the reaction is complete, centrifuge the suspension at 2000 r / min for 8 min. Wash the precipitate once with deionized water and then dry it in a vacuum drying oven at 80℃ for 2 h. Grind it through a 100-mesh sieve to obtain activated calcium carbonate.

[0021] In step C2, while maintaining the temperature and stirring, add 0.5 parts of γ-aminopropyltriethoxysilane to the three-necked flask.

[0022] Bamboo fiber modified and reinforced polypropylene composite material, comprising the following steps: S1. Add functionalized polypropylene and compatibilizer to a high-speed mixer and stir at 80°C for 3 min. Add modified bamboo fiber and activated calcium carbonate and stir for 3 min. Add antioxidant and lubricant and stir for 2 min to form a premix. S2. Using a twin-screw extruder with a length-to-diameter ratio of 30:1, the premixed material is added to the feed hopper. The extrusion temperature gradient is: Zone 1 145℃, Zone 2 165℃, Zone 3 175℃, Zone 4 185℃, screw speed 240 r / min, material residence time 8 min. The extruded strip is cooled by a 15℃ water cooling device and pelletized by an underwater pelletizer to a diameter of 2 mm. It is then transferred to a forced-air drying oven and dried at 80℃ for 4 hours. After cooling to room temperature, the composite material is obtained.

[0023] Example 2, bamboo fiber modified and reinforced polypropylene composite material, comprising the following parts by weight of raw materials: Functionalized polypropylene 70 parts, modified bamboo fiber 25 parts, activated calcium carbonate 10 parts, compatibilizer 6 parts, antioxidant 1 part, lubricant 0.5 parts; The compatibilizer is a mixture of maleic anhydride-grafted polypropylene and citric acid in a mass ratio of 3:0.8. The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:0.8; The lubricant is a compound of calcium stearate and polyethylene wax in a mass ratio of 2:1.2.

[0024] The preparation method of reinforced polypropylene includes the following steps: A1. Place 110 parts of polypropylene in a vacuum drying oven at 85℃ for 5 h, cool and then transfer to a plasma treatment device. Use argon gas to bombard for 4 min, with a power of 350 W and a vacuum degree of 0.05 MPa. A2. The plasma-treated polypropylene, 9 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 4.5 parts of sodium hydroxide, 3.5 parts of glycidyl methacrylate, 2.5 parts of cysteine ​​hydrochloride, 1.2 parts of hexamethylene diisocyanate, 0.6 parts of styrene, and 0.7 parts of divinylbenzene were sequentially added to a high-speed mixer, followed by 0.7 parts of dicumyl peroxide. The mixture was stirred at 400 r / min for 20 min to form a mixture. A3. Add the mixture to a twin-screw extruder with a length-to-diameter ratio of 35:1, temperature gradient: zone 1 145℃, zone 2 160℃, zone 3 175℃, zone 4 185℃, screw speed 250 r / min, material residence time 10 min, and extruded strip is water-cooled at 20℃ and vacuum-dried at 70℃ for 7 h to obtain functionalized polypropylene.

[0025] The preparation method of modified bamboo fiber includes the following steps: B1. Add 110 parts activated bamboo fiber, 18 parts succinic anhydride, 6 parts pyridine, and 400 parts ethanol to a round-bottom flask, heat to reflux, and stir at a constant temperature for 2.5 h. After the reaction is complete, wash twice with deionized water and dry under vacuum at 70℃ for 7 h to obtain carboxylated bamboo fiber. B2. Immerse 85 parts of carboxylated bamboo fiber in a 4% (w / w) aqueous solution of zinc chloride, disperse with ultrasonic assistance at 250 W and 35 kHz for 30 min, stir at room temperature for 1.5 h, filter to separate the fiber, wash with deionized water 4 times, and vacuum dry at 70℃ for 7 h to obtain zinc ion complexed bamboo fiber. B3. Add 70 parts of zinc ion complexed bamboo fiber and 12 parts of ammonium polyphosphate to a high-speed mixer, add 450 parts of deionized water, stir and mix at 70°C for 20 min, transfer to a 105°C forced-air drying oven, dry for 1.5 h, cool to room temperature, pulverize, and pass through a 120-mesh sieve to obtain modified bamboo fiber.

[0026] The preparation method of activated bamboo fiber in step B1 is as follows: Take 180 parts of bamboo fiber and place them in 1000 parts of 1% sodium hydroxide solution. Boil at 70℃ for 1 h. After taking them out, wash them repeatedly with deionized water until neutral. Transfer them to a freeze dryer at -45℃ and dry for 45 h to obtain activated bamboo fiber.

[0027] In step B3, before the zinc ion-complexed bamboo fiber is added to the high-speed mixer, it is placed in a plasma treatment device and bombarded with oxygen plasma for 3 minutes at a power of 280 W and a vacuum degree of 0.05 MPa.

[0028] The preparation method of activated calcium carbonate includes the following steps: C1. Place 90 parts of calcium carbonate powder in a 105℃ forced-air drying oven and dry for 2 hours. Cool to room temperature, then add 4 parts of sodium citrate and 700 parts of deionized water to a three-necked flask, stir and disperse to form a suspension, and adjust the pH to 6.8 with dilute hydrochloric acid. C2. Place the three-necked flask in a constant temperature water bath and keep it at 75℃ with stirring for 2 hours. After the reaction is complete, centrifuge the suspension at 2500 r / min for 9 minutes. Wash the precipitate twice with deionized water and then dry it in a vacuum drying oven at 90℃ for 3 hours. Grind it through a 150-mesh sieve to obtain activated calcium carbonate.

[0029] In step C2, while maintaining the temperature and stirring, add 1 part of γ-aminopropyltriethoxysilane to the three-necked flask.

[0030] Bamboo fiber modified and reinforced polypropylene composite material, comprising the following steps: S1. Add functionalized polypropylene and compatibilizer to a high-speed mixer and stir at 90°C for 4 min. Add modified bamboo fiber and activated calcium carbonate and stir for 4 min. Add antioxidant and lubricant and stir for 3 min to form a premix. S2. Using a twin-screw extruder with a length-to-diameter ratio of 35:1, the premixed material is added to the feed hopper. The extrusion temperature gradient is: Zone 1 150℃, Zone 2 170℃, Zone 3 180℃, Zone 4 180℃, screw speed 250 r / min, material residence time 10 min. The extruded strip is cooled by a 20℃ water cooling device and pelletized by an underwater pelletizer to a diameter of 2 mm. It is then transferred to a forced-air drying oven and dried at 90℃ for 5 hours. After cooling to room temperature, the composite material is obtained.

[0031] Example 3, bamboo fiber modified and reinforced polypropylene composite material, comprising the following parts by weight of raw materials: Functionalized polypropylene 80 parts, modified bamboo fiber 35 parts, activated calcium carbonate 15 parts, compatibilizer 8 parts, antioxidant 1.5 parts, lubricant 0.8 parts; The compatibilizer is a mixture of maleic anhydride-grafted polypropylene and citric acid in a mass ratio of 3:1. The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1. The lubricant is a compound of calcium stearate and polyethylene wax in a mass ratio of 2:1.5.

[0032] The preparation method of reinforced polypropylene includes the following steps: A1. Place 120 parts of polypropylene in a vacuum drying oven at 90℃ and dry for 6 hours. After cooling, transfer them to a plasma treatment device and bombard them with argon gas for 5 minutes at a power of 400 W and a vacuum degree of 0.06 MPa. A2. The plasma-treated polypropylene, 10 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 5 parts of sodium hydroxide, 4 parts of glycidyl methacrylate, 3 parts of cysteine ​​hydrochloride, 1.5 parts of hexamethylene diisocyanate, 1 part of styrene, and 0.8 parts of divinylbenzene were sequentially added to a high-speed mixer, followed by 0.8 parts of dicumyl peroxide. The mixture was stirred at 500 r / min for 25 min to form a mixture. A3. Add the mixture to a twin-screw extruder with a length-to-diameter ratio of 40:1, temperature gradient: zone 1 150℃, zone 2 165℃, zone 3 180℃, zone 4 190℃, screw speed 260 r / min, material residence time 10 min, and extruded strip is water-cooled at 25℃ and vacuum-dried at 80℃ for 8 h to obtain functionalized polypropylene.

[0033] The preparation method of modified bamboo fiber includes the following steps: B1. Add 120 parts activated bamboo fiber, 20 parts succinic anhydride, 8 parts pyridine, and 500 parts ethanol to a round-bottom flask, heat to reflux, and stir at a constant temperature for 3 hours. After the reaction is complete, wash with deionized water 3 times and dry under vacuum at 80°C for 8 hours to obtain carboxylated bamboo fiber. B2. Immerse 90 parts of carboxylated bamboo fiber in a 5% (w / w) aqueous solution of zinc chloride containing metal ions, and disperse with ultrasonic assistance at 300 W and 40 kHz for 30 min. Stir and react at room temperature for 2 h, filter to separate the fiber, wash with deionized water 5 times, and vacuum dry at 80℃ for 8 h to obtain zinc ion complexed bamboo fiber. B3. Add 80 parts of zinc ion complexed bamboo fiber and 15 parts of ammonium polyphosphate to a high-speed mixer, add 500 parts of deionized water, stir and mix at 80°C for 30 min, transfer to a 110°C forced-air drying oven, dry for 2 h, cool to room temperature, pulverize, and pass through a 150-mesh sieve to obtain modified bamboo fiber.

[0034] The preparation method of activated bamboo fiber in step B1 is as follows: Take 200 parts of bamboo fiber and place them in 1200 parts of 2% sodium hydroxide solution. Boil at 80℃ for 2 hours. After taking them out, wash them repeatedly with deionized water until neutral. Transfer them to a freeze dryer at -50℃ and dry for 50 hours to obtain activated bamboo fiber.

[0035] In step B3, before the zinc ion-complexed bamboo fiber is added to the high-speed mixer, it is placed in a plasma treatment device and bombarded with oxygen plasma for 3 minutes at a power of 300 W and a vacuum degree of 0.06 MPa.

[0036] The preparation method of activated calcium carbonate includes the following steps: C1. Place 100 parts of calcium carbonate powder in a 110℃ forced-air drying oven and dry for 3 hours. Cool to room temperature, then add 5 parts of sodium citrate and 800 parts of deionized water to a three-necked flask, stir and disperse to form a suspension, and adjust the pH to 7.0 with dilute hydrochloric acid. C2. Place the three-necked flask in a constant temperature water bath and keep it at 80℃ with stirring for 2 hours. After the reaction is complete, centrifuge the suspension at 3000 r / min for 10 minutes. Wash the precipitate three times with deionized water and then dry it in a vacuum drying oven at 100℃ for 4 hours. Grind it through a 200-mesh sieve to obtain activated calcium carbonate.

[0037] In step C2, while maintaining the temperature and stirring, add 1.5 parts of γ-aminopropyltriethoxysilane to the three-necked flask.

[0038] Bamboo fiber modified and reinforced polypropylene composite material, comprising the following steps: S1. Add functionalized polypropylene and compatibilizer to a high-speed mixer and stir at 100°C for 5 min. Add modified bamboo fiber and activated calcium carbonate and stir for 5 min. Add antioxidant and lubricant and stir for 3 min to form a premix. S2. Using a twin-screw extruder with a length-to-diameter ratio of 40:1, the premixed material is added to the feed hopper. The extrusion temperature gradient is: Zone 1 155℃, Zone 2 175℃, Zone 3 185℃, Zone 4 195℃, screw speed 260 r / min, material residence time 10 min. The extruded strip is cooled by a 25℃ water cooling device and pelletized by an underwater pelletizer to a diameter of 3 mm. It is then transferred to a forced-air drying oven and dried at 100℃ for 6 hours. After cooling to room temperature, the composite material is obtained.

[0039] Comparative Example 1: Functionalized polypropylene, modified bamboo fiber, and activated calcium carbonate were replaced with equal masses of polypropylene, bamboo fiber, and calcium carbonate, while the remaining components and processes were the same as in Example 1.

[0040] Comparative Example 2: Functionalized polypropylene was replaced with an equal mass of polypropylene, and the remaining components and processes were the same as in Example 1.

[0041] Comparative Example 3: Modified bamboo fiber was replaced with an equal mass of bamboo fiber, and the remaining components and processes were the same as in Example 1.

[0042] Performance testing: 1. Mechanical property testing: Tensile strength: Refer to GB / T 1040.2-2022, specimen type: Type I dumbbell specimen, test conditions: tensile speed 50 mm / min, 25℃; Bending strength: Refer to GB / T 9341-2008, sample type: 80×10×4 mm strip, test conditions: span 64 mm, speed 2 mm / min; Notched impact strength: Refer to GB / T 1843-2008, sample type: 80×10×4 mm, type A notch, test conditions: pendulum energy 2.75 J, 25℃; 2. Antistatic performance test: Surface resistivity: Refer to GB / T 31838.2-2019; Sample type: 100×100 mm plate; Test conditions: Voltage 500 V, 25℃, humidity 50%; Volume resistivity: Refer to GB / T 31838.2-2019, sample type: 100×100 mm plate, test conditions: voltage 500 V, 25℃, humidity 50%; Electrostatic half-life: Refer to GB / T 31838.2-2019; Sample type: 45×45 mm specimen; Test conditions: Voltage ±10 kV, 25℃, humidity 50%; 3. Flame retardant performance test: Vertical burning rating: Refer to GB / T 2408-2021, sample size: 125×13×3.2 mm, test conditions: flame height 20 mm, flame applied twice, 10 s each time; Limiting oxygen index: Refer to GB / T 2406.2-2009, sample type: 80×10×4 mm, test conditions: oxygen concentration adjustment, test critical oxygen concentration; Table 1. Mechanical property test results Group Tensile strength (MPa) Bending strength (MPa) <![CDATA[Izod impact strength (kJ / m 2 )]]> Example 1 48.2 62.3 7.5 Example 2 51.6 66.8 7.9 Example 3 49.5 64.1 7.8 Comparative Example 1 38.1 48.6 5.1 Comparative Example 2 42.3 52.8 5.6 Comparative Example 3 45.5 56.3 6.4 Table 2 Results of Antistatic Performance Test Group Surface resistivity (Ω) Volume resistivity (Ω·cm) Electrostatic half-life (s) Example 1 <![CDATA[2.3×10 8 ]]> <![CDATA[1.5×10 9 ]]> 1.2 Example 2 <![CDATA[1.8×10 8 ]]> <![CDATA[1.2×10 9 ]]> 0.9 Example 3 <![CDATA[2.1×10 8 ]]> <![CDATA[1.4×10 9 ]]> 1.1 Comparative Example 1 <![CDATA[2.1×10 15 ]]> <![CDATA[8.5×10 15 ]]> >180 Comparative Example 2 <![CDATA[3.6×10 14 ]]> <![CDATA[1.2×10 15 ]]> >120 Comparative Example 3 <![CDATA[2.8×10 9 ]]> <![CDATA[5.6×10 9 ]]> 2.8 Table 3 Flame retardant performance test results Group Vertical flammability rating Limiting oxygen index (%) Example 1 V-2 24.5 Example 2 V-2 25.2 Example 3 V-2 24.8 Comparative Example 1 No grade 18.2 Comparative Example 2 No grade 19.5 Comparative Example 3 HB 21.0 As shown in the table above, the synergistic effect of functionalized polypropylene, modified bamboo fiber, and activated calcium carbonate strengthens the interfacial bonding of the three phases, reduces stress concentration, and maintains toughness while improving strength. The zinc ion complexation of modified bamboo fiber forms a stable conductive pathway, effectively improving antistatic properties. The synergistic effect of ammonium polyphosphate loaded on modified bamboo fiber and zinc ions inhibits the migration of flame-retardant components and improves combustion stability.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bamboo fiber-modified reinforced polypropylene composite material, characterized in that, Includes the following quantities of raw materials: Functionalized polypropylene 60-80 parts, modified bamboo fiber 15-35 parts, activated calcium carbonate 5-15 parts, compatibilizer 4-8 parts, antioxidant 0.5-1.5 parts, lubricant 0.3-0.8 parts; The compatibilizer is prepared by compounding maleic anhydride-grafted polypropylene and citric acid in a mass ratio of 3:0.5~1. The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:0.5~1; The lubricant is a compound of calcium stearate and polyethylene wax in a mass ratio of 2:1 to 1.

5. The method for preparing the reinforced polypropylene includes the following steps: A1. Place 100-120 parts of polypropylene in a vacuum drying oven at 80-90℃ and dry for 4-6 hours. After cooling, transfer them to a plasma treatment device and bombard them with argon gas for 3-5 minutes at a power of 300-400 W and a vacuum degree of 0.05-0.06 MPa. A2. Add the plasma-treated polypropylene, 8-10 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 4-5 parts of sodium hydroxide, 3-4 parts of glycidyl methacrylate, 2-3 parts of cysteine ​​hydrochloride, 1-1.5 parts of hexamethylene diisocyanate, 0.5-1 part of styrene, and 0.5-0.8 parts of divinylbenzene to a high-speed mixer in sequence, then add 0.6-0.8 parts of dicumyl peroxide, and stir at 300-500 r / min for 20-25 min to form a mixture; A3. Add the mixture to a twin-screw extruder with a length-to-diameter ratio of 30~40:1, temperature gradient: zone 1 140~150℃, zone 2 155~165℃, zone 3 170~180℃, zone 4 180~190℃, screw speed 230~260 r / min, material residence time 8~10 min, and extruded strips are water-cooled at 15~25℃ and vacuum-dried at 60~80℃ for 6~8 h to obtain functionalized polypropylene.

2. The bamboo fiber modified and reinforced polypropylene composite material according to claim 1, characterized in that, The preparation method of modified bamboo fiber includes the following steps: B1. Add 100-120 parts of activated bamboo fiber, 15-20 parts of succinic anhydride, 5-8 parts of pyridine, and 300-500 parts of ethanol to a round-bottom flask, heat to reflux, and stir at a constant temperature for 2-3 hours. After the reaction is complete, wash with deionized water 2-3 times and dry under vacuum at 60-80℃ for 6-8 hours to obtain carboxylated bamboo fiber. B2. Immerse 80-90 parts of carboxylated bamboo fiber in a 3-5% (w / w) aqueous solution of zinc chloride containing metal ions, and disperse using ultrasonic assistance at a power of 200-300W and a frequency of 30-40 kHz for 20-30 min. Stir the reaction at room temperature for 1.5-2 h, filter to separate the fiber, wash with deionized water 3-5 times, and vacuum dry at 60-80℃ for 6-8 h to obtain zinc ion complexed bamboo fiber. B3. Add 60-80 parts of zinc ion complexed bamboo fiber and 10-15 parts of ammonium polyphosphate to a high-speed mixer, add 400-500 parts of deionized water, stir and mix at 60-80℃ for 15-30 min, transfer to a 100-110℃ forced-air drying oven, dry for 1-2 h, cool to room temperature, pulverize, and pass through a 100-150 mesh sieve to obtain modified bamboo fiber.

3. The bamboo fiber modified and reinforced polypropylene composite material according to claim 2, characterized in that, The preparation method of activated bamboo fiber in step B1 is as follows: Take 150~200 parts of bamboo fiber and place them in 800~1200 parts of 0.5~2% sodium hydroxide solution, boil at 60~80℃ for 0.5~2 h, take them out and wash them repeatedly with deionized water until neutral, transfer them to a freeze dryer at -40~-50℃ and dry for 40~50 h to obtain activated bamboo fiber.

4. The bamboo fiber modified and reinforced polypropylene composite material according to claim 2, characterized in that, In step B3, before adding the zinc ion-complexed bamboo fiber to the high-speed mixer, it is placed in a plasma treatment device and bombarded with oxygen plasma for 2-3 minutes at a power of 250-300 W and a vacuum degree of 0.05-0.06 MPa.

5. The bamboo fiber modified and reinforced polypropylene composite material according to claim 1, characterized in that, The preparation method of activated calcium carbonate includes the following steps: C1. Place 80-100 parts of calcium carbonate powder in a 100-110℃ forced-air drying oven and dry for 2-3 hours. Cool to room temperature, then add 3-5 parts of sodium citrate and 600-800 parts of deionized water to a three-necked flask, stir and disperse to form a suspension, and adjust the pH to 6.5-7.0 with dilute hydrochloric acid. C2. Place the three-necked flask in a constant temperature water bath and keep it at 70~80℃ with stirring for 1.5~2 h. After the reaction is complete, centrifuge the suspension at 2000~3000 r / min for 8~10 min. Wash the precipitate with deionized water 1~3 times, and then dry it in a vacuum drying oven at 80~100℃ for 2~4 h. Grind it through a 100~200 mesh sieve to obtain activated calcium carbonate.

6. The bamboo fiber modified and reinforced polypropylene composite material according to claim 5, characterized in that, In step C2, while maintaining the temperature and stirring, add 0.5 to 1.5 parts of γ-aminopropyltriethoxysilane to the three-necked flask.

7. The bamboo fiber modified reinforced polypropylene composite material according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Add functionalized polypropylene and compatibilizer to a high-speed mixer and stir at 80~100℃ for 3~5 min. Add modified bamboo fiber and activated calcium carbonate and stir for 3~5 min. Add antioxidant and lubricant and stir for 2~3 min to form a premix. S2. Using a twin-screw extruder with a length-to-diameter ratio of 30~40:1, the premixed material is added to the feed hopper. The extrusion temperature gradient is: Zone 1 145~155℃, Zone 2 165~175℃, Zone 3 175~185℃, Zone 4 185~195℃, screw speed 240~260 r / min, material residence time 8~10 min, the extruded strip is cooled by a 15~25℃ water cooling device, and then pelletized by an underwater pelletizer to a diameter of 2~3 mm. The pellets are then transferred to a forced-air drying oven and dried at 80~100℃ for 4~6 h. After cooling to room temperature, the composite material is obtained.