Antistatic light-weight plastic-wood composite material and preparation method thereof

Abstract

This invention relates to the field of lightweight wood-plastic composite materials, specifically to an antistatic lightweight wood-plastic composite material and its preparation method, which addresses the problems of insufficient antistatic properties and high density in existing wood-plastic composite materials. The method involves mixing an antistatic agent with high-density polyethylene, extruding, cooling, crushing, and sieving to obtain an antistatic masterbatch. Modified wood flour, high-density polyethylene, maleic anhydride graft compatibilizer, antioxidant, 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane are then mixed, cooled, and the antistatic masterbatch is added for further mixing. The mixture is fed into a twin-screw extruder, and cobalt ferrite-coated hollow glass microspheres are added. After extrusion, cooling, and crushing, the mixture is then subjected to secondary molding in a single-screw extruder, gradient cooling for shaping, and traction cutting to obtain the antistatic lightweight wood-plastic composite material. This material possesses excellent antistatic properties, low density, and lightweight characteristics, along with good flexural strength and impact strength, low water absorption, and excellent water resistance.

Description

Technical Field

[0001] This invention relates to the field of lightweight wood-plastic composite materials, specifically to an antistatic lightweight wood-plastic composite material and its preparation method. Background Technology

[0002] Wood-plastic composites, as an environmentally friendly alternative to wood and plastics, have advantages such as corrosion resistance, moisture resistance, dimensional stability, and recyclability, and have been widely used in various scenarios. However, traditional wood-plastic composites have two major drawbacks: first, their antistatic properties are insufficient, and they are prone to accumulating static electricity in environments such as petrochemical and electronics workshops, which may cause sparks or even explosions; second, their high density limits their application in weight-sensitive scenarios such as rooftop platforms and high-altitude facilities.

[0003] Existing antistatic wood-plastic composites mostly involve adding a single antistatic agent or metal powder, resulting in problems such as short-lasting antistatic effects and uneven dispersion. Meanwhile, lightweight solutions often rely on simple foaming, which easily leads to decreased mechanical properties and increased water absorption. Therefore, developing a wood-plastic composite material with stable antistatic effects, low density, and excellent mechanical properties has become a pressing technical challenge for the industry. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide an antistatic lightweight wood-plastic composite material and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions: In a first aspect, this application provides an antistatic lightweight wood-plastic composite material, comprising the following components in parts by weight: 50-70 parts wood flour, 250-400 parts sodium hydroxide aqueous solution, 2-5 parts antistatic agent, 20-40 parts high-density polyethylene, 8-15 parts maleic anhydride graft compatibilizer, 1-3 parts antioxidant, 2-5 parts 2-hydroxy-4-methoxybenzophenone, 1-2 parts γ-aminopropyltriethoxysilane, and 5-10 parts cobalt ferrite-coated hollow glass microspheres. The antistatic agent is prepared by the following steps: Step a1: Place melamine in an agate mortar and grind for 20-22 minutes. Then place it in a muffle furnace and heat it to 550°C at a heating rate of 5°C / min. Calcinate at a constant temperature for 4 hours. After calcination, allow it to cool naturally to room temperature. Grind it in an agate mortar and pass it through a 100-mesh standard sieve to obtain graphite phase carbon nitride powder. Step a2: Add graphitic carbon nitride powder, 1,4-dibromobutane, dimethyl sulfoxide, and potassium carbonate to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and reflux condenser. Purge with nitrogen for protection and stir at 25-30℃ and 300-400 r / min for 30-35 min. Then raise the temperature to 85-90℃ and stir for 24-25 h. After the reaction is complete, allow it to cool naturally to room temperature. Collect the solid product by vacuum filtration. Wash it 10 times with petroleum ether using ultrasonication, each time with a power of 300W and a time of 10 min. Then filter it and wash it twice with anhydrous ethanol. Place the solid in a vacuum drying oven and dry it for 14-15 h at 55-60℃ and a vacuum of -0.09 MPa. Grind and pass through a 120-mesh sieve to obtain bromoalkyl-modified graphitic carbon nitride powder. Step a3: Add bromoalkyl-modified graphitic carbon nitride powder, 1-hexylimidazole, and dimethyl sulfoxide to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir the mixture at 65-70℃ and a stirring rate of 300-400 r / min for 24 h. After the reaction is complete, cool to room temperature, collect the solid product by vacuum filtration, wash 8 times with petroleum ether, wash once with anhydrous ethanol after vacuum filtration, and then place it in a vacuum drying oven and dry it at 55-60℃ and a vacuum of -0.09 MPa for 10-12 h. Grind and pass through a 120-mesh sieve to obtain the antistatic agent.

[0006] In a preferred embodiment of the present invention, the ratio of the graphitic carbon nitride powder, 1,4-dibromobutane, dimethyl sulfoxide and potassium carbonate used in step a2 is 2-3g: 28.1-42.2g: 40-60mL: 0.2-0.3g.

[0007] In a preferred embodiment of the present invention, the ratio of the bromoalkyl-modified graphitic carbon nitride powder, 1-hexylimidazole and dimethyl sulfoxide in step a3 is 1.5-2.1g: 5-7g: 37.5-52.5mL.

[0008] The cobalt ferrite-coated hollow glass microspheres are prepared by the following steps: Step b1: Add hollow glass microsphere powder and sodium hydroxide solution to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen for protection and stir for 20-25 min at a temperature of 75-80℃ and a stirring rate of 300-400 r / min. Then transfer to an ultrasonic cleaner and sonicate for 20-22 min at a power of 300W. Collect the solid product by filtration and wash repeatedly with deionized water until the filtrate is neutral. Then place it in a vacuum drying oven and dry for 6-7 h at a temperature of 75-80℃ and a vacuum degree of −0.09MPa. After grinding, pass through a 100-mesh sieve to obtain pretreated hollow glass microspheres. Step b2: Add cobalt nitrate hexahydrate, ferric nitrate nonahydrate, citric acid, and deionized water to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection. Stir the reaction at 25-30℃ and a stirring rate of 200-250 rpm for 20-30 minutes. Then, sonicate the solution at 300W for 20-22 minutes. While stirring, add ammonia dropwise to adjust the pH to 7. Add pretreated hollow glass microspheres and continue sonication for 20-22 minutes. Place the three-necked flask at a constant temperature of 80℃. The mixture was stirred in a water bath for 2-3 hours, then removed and allowed to stand at room temperature for 2 hours. It was then transferred to a 120℃ constant temperature oven and dried for 24 hours to obtain a dry gel. The dry gel was crushed and transferred to a muffle furnace, heated to 600℃ at a heating rate of 5℃ / min, and calcined for 4 hours. After naturally cooling to room temperature, it was washed 1-2 times with distilled water, filtered, and placed in a vacuum drying oven. It was dried for 2-3 hours at a temperature of 75-80℃ and a vacuum degree of -0.09MPa. After that, it was ball-milled for 30-32 minutes and passed through a 120-mesh sieve to obtain cobalt ferrite-coated hollow glass microspheres.

[0009] In a preferred embodiment of the present invention, the ratio of hollow glass microsphere powder to sodium hydroxide solution in step b1 is 10-12g:100-120mL.

[0010] In a preferred embodiment of the present invention, the concentration of the sodium hydroxide solution in step b1 is 3 mol / L.

[0011] In a preferred embodiment of the present invention, the ratio of cobalt nitrate hexahydrate, ferric nitrate nonahydrate, citric acid, deionized water and pretreated hollow glass microspheres in step b2 is 2.9-5.8g: 8-16g: 4.2-8.4g: 50-100mL: 1-2g.

[0012] In a preferred embodiment of the present invention, the mass fraction of the ammonia water in step b2 is 25%.

[0013] Secondly, this application provides a method for preparing an antistatic lightweight wood-plastic composite material, comprising the following steps: Step 1: Weigh out 50-70 parts by weight of wood flour, 250-400 parts by weight of sodium hydroxide aqueous solution, 2-5 parts by weight of antistatic agent, 20-40 parts by weight of high-density polyethylene, 8-15 parts by weight of maleic anhydride graft compatibilizer, 1-3 parts by weight of antioxidant, 2-5 parts by weight of 2-hydroxy-4-methoxybenzophenone, 1-2 parts by weight of γ-aminopropyltriethoxysilane, and 5-10 parts by weight of cobalt ferrite-coated hollow glass microspheres, and set aside. Step 2: Soak the wood flour in an aqueous sodium hydroxide solution for 2 hours, then wash it with deionized water until neutral, centrifuge it at 800-1000 r / min for 5-10 minutes to remove water, then place it in a vacuum drying oven and dry it at 100-105℃ and -0.09 MPa for 4-5 hours. Grind the wood flour and pass it through a 100-mesh standard sieve to obtain modified wood flour. Step 3: Place the antistatic agent and 1 / 3 of the high-density polyethylene into a high-speed mixer and mix for 10-12 minutes at a temperature of 55-60℃ and a speed of 60-85 r / min. Then feed it into a twin-screw extruder with a barrel temperature of 160-180℃, a die temperature of 170-185℃, and a screw speed of 30 r / min. After extrusion, cool and crush the material and pass it through a 100-mesh sieve to obtain antistatic masterbatch. Step 4: Add modified wood flour, 2 / 3 high-density polyethylene, maleic anhydride graft compatibilizer, antioxidant, 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane to a high-speed mixer and mix for 15-25 minutes at 60-80℃ and 60-85 r / min. Then lower the temperature to 40-50℃, add antistatic masterbatch, and mix for 10-15 minutes. Then feed the mixture into a twin-screw extruder, with vacuum degassing enabled. Cobalt ferrite-coated hollow glass microspheres are then passed through... The material is fed separately through the side feed port of the twin-screw extruder. The barrel temperature is 160-190℃, the die temperature is 170-200℃, and the screw speed is 30-40 r / min. After extrusion, the material is cooled and crushed, and then fed into a single-screw extruder for secondary melt extrusion molding. The length-to-diameter ratio is 25:1, the barrel temperature is 170-205℃, the die temperature is 180-210℃, the feed speed is 20-40Hz, and the main extruder speed is 30-50Hz. After gradient cooling and shaping, and traction cutting, an antistatic lightweight wood-plastic composite material is obtained.

[0014] In a preferred embodiment of the present invention, the wood powder in step one is pine wood powder with a particle size of 100 mesh; the sodium hydroxide aqueous solution has a mass fraction of 5%.

[0015] In a preferred embodiment of the present invention, the high-density polyethylene in step two is produced by Yanshan Petrochemical and is model HDPE 5000S.

[0016] In a preferred embodiment of the present invention, the antioxidant in step three is antioxidant 1010; and the maleic anhydride graft compatibilizer is FUSABOND® E265.

[0017] The beneficial effects of this invention are: This invention discloses an antistatic lightweight wood-plastic composite material and its preparation method. The method involves soaking wood flour in an aqueous sodium hydroxide solution, followed by washing, centrifugal dehydration, drying, grinding, and sieving to obtain modified wood flour. An antistatic agent is mixed with high-density polyethylene, and the mixture is extruded using a twin-screw extruder, cooled, crushed, and sieved to obtain antistatic masterbatch. Modified wood flour, high-density polyethylene, maleic anhydride graft compatibilizer, antioxidant, 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane are then added to a high-speed mixer for mixing. After cooling, the antistatic masterbatch is added and mixing continues. The mixture is then fed into a twin-screw extruder. Cobalt ferrite-coated hollow glass microspheres are added separately through a side feed port. After extrusion, cooling and crushing, the mixture is then melt-extruded again using a single-screw extruder. After gradient cooling and shaping, it is traction-cut to finally obtain the antistatic lightweight wood-plastic composite material. Antistatic agents can construct efficient ion conduction channels for antistatic lightweight wood-plastic composites, endowing them with excellent and long-lasting antistatic properties. They also exhibit good compatibility with the matrix and can slightly improve the material's density and water resistance through filling, ensuring the long-term performance stability of the composite material. Cobalt ferrite-coated hollow glass microspheres not only impart low-density and lightweight characteristics to the antistatic lightweight wood-plastic composites due to their hollow structure, but also enhance the interfacial bonding force with the polymer matrix through the cobalt ferrite coating, increasing the material's flexural and impact strength. Simultaneously, they reduce interfacial gaps, lower water absorption, and improve the composite material's water resistance and overall performance stability. Therefore, antistatic lightweight wood-plastic composites possess excellent antistatic properties, low-density and lightweight characteristics, good flexural and impact strength, low water absorption, and excellent water resistance.

[0018] In the preparation of antistatic lightweight wood-plastic composite materials, an antistatic agent was first prepared. Melamine underwent intermolecular condensation reaction after high-temperature calcination, resulting in the removal of ammonia and the formation of graphitic carbon nitride powder with a layered conjugated structure. Then, in the polar aprotic solvent dimethyl sulfoxide, the active amino groups on the surface of the graphitic carbon nitride underwent nucleophilic substitution with 1,4-dibromobutane. Potassium carbonate, acting as an acid-binding agent, absorbed the hydrogen bromide generated in the reaction to drive the reaction forward, achieving covalent grafting of bromoalkyl groups onto the surface of the graphitic carbon nitride. Subsequently, the bromoterminated bromine end groups on the surface of the bromoalkyl-modified graphitic carbon nitride underwent quaternization with 1-hexylimidazole, forming ionic bonds through the nucleophilic interaction of nitrogen atoms, thereby grafting imidazole onion groups onto the surface of the graphitic carbon nitride, ultimately yielding a functionalized antistatic agent with ion conductivity. This antistatic agent uses melamine as a precursor, and the process of gradient-temperature calcination combined with sieving ensures the high efficiency of the graphitic carbon nitride. The crystallinity and complete layered conjugated structure ensure uniform particle size, providing a stable reaction substrate for subsequent modification. Dimethyl sulfoxide (DMSO) was then used as a polar aprotic solvent, combined with potassium carbonate as an acid-binding agent, effectively solving the compatibility problem between inorganic powders and organic reagents. Excess 1,4-dibromobutane ensured complete modification of the amino groups on the surface of the graphitic carbon nitride. A multi-stage washing process using petroleum ether and anhydrous ethanol efficiently removed unreacted raw materials and solvent residues, precisely introducing active bromine end groups. The layered conjugated structure of the graphitic carbon nitride provides a continuous channel for electron migration, and the imidazolium salt groups grafted onto its surface can dissociate mobile cations, forming ion conduction pathways. These two elements synergistically construct an electron-ion dual conductive pathway, rapidly dissipating static charge. The grafted organic groups enhance the compatibility between the antistatic agent and the matrix. Combined with the masterbatch dispersion process, the integrity of the conductive network is ensured, and the ionic groups, grafted via covalent bonds, are not easily migrated or lost, achieving a long-lasting antistatic effect.

[0019] In the preparation of antistatic lightweight wood-plastic composite materials, a cobalt ferrite-coated hollow glass microsphere was prepared. First, the hollow glass microspheres were subjected to alkaline etching with sodium hydroxide solution, which removed the silicon oxide on their surface by reacting with the alkali, while simultaneously introducing a large number of active hydroxyl groups, providing binding sites for subsequent coating. Subsequently, the Co ferrite released after the dissolution of cobalt nitrate hexahydrate and ferric nitrate nonahydrate... 2+ with Fe 3+A stable precursor sol is formed under the complexation of citric acid. After adjusting the pH to 7 with ammonia, the sol is uniformly adsorbed onto the surface of pretreated hollow glass microspheres through hydrogen bonding. The sol is then concentrated in a water bath and dried to form a dry gel. During high-temperature calcination, the citric acid complexing agent decomposes and escapes, and the nitrates first decompose into cobalt oxide and iron oxide. These two oxides further undergo a solid-phase reaction to generate spinel-type cobalt ferrite crystals. After ball milling, cobalt ferrite-coated hollow glass microspheres are obtained. The pretreatment method of alkaline etching combined with ultrasound in the preparation of these cobalt ferrite-coated hollow glass microspheres can efficiently remove silicon oxide impurities from the surface of the hollow glass microspheres and introduce active hydroxyl groups. This not only improves the interfacial bonding force between the microspheres and the cobalt ferrite but also avoids the formation of harmful chemical residues through mild process conditions. Microspheres are broken down to maintain their lightweight properties; the sol-gel method uses citric acid to complex metal ions to form a stable precursor sol, achieving a dense molecular-level coating of cobalt ferrite on the surface of the microspheres, effectively avoiding problems of uneven coating or agglomeration; hollow glass microspheres endow the composite material with low-density properties, realizing the lightweighting of wood-plastic composites; the spinel-type cobalt ferrite coating on the surface enhances the rigidity of the filler and strengthens the mechanical properties of the composite material; the active hydroxyl groups and cobalt ferrite coating layer introduced by the alkaline etching pretreatment improve the interfacial compatibility between the microspheres and the polymer matrix, avoid filler agglomeration, and ensure the uniformity of material properties; the final product combines the low-density properties of hollow microspheres with the rigidity-enhancing function of cobalt ferrite, and its surface active groups can improve the compatibility with the polymer matrix. Detailed Implementation

[0020] 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.

[0021] Example 1:

[0022] This embodiment describes a method for preparing an antistatic lightweight wood-plastic composite material, including the following steps: Step S1: Place 5g of melamine in an agate mortar and grind for 20min. Then place it in a muffle furnace and heat it to 550℃ at a heating rate of 5℃ / min. Calcinate at a constant temperature for 4h. After calcination, allow it to cool naturally to room temperature. Grind it in an agate mortar and pass it through a 100-mesh standard sieve to obtain graphite phase carbon nitride powder. Step S2: 2g of graphitic carbon nitride powder, 28.1g of 1,4-dibromobutane, 40mL of dimethyl sulfoxide, and 0.2g of potassium carbonate were added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and reflux condenser. Nitrogen gas was introduced for protection, and the mixture was stirred at 25℃ and a stirring rate of 300r / min for 30min. Then the temperature was raised to 85℃ and the mixture was stirred for 24h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The solid product was then collected by vacuum filtration. It was first ultrasonically washed 10 times with petroleum ether, with each ultrasonic power of 300W and time of 10min. After vacuum filtration, it was washed twice with anhydrous ethanol. The solid was placed in a vacuum drying oven and dried at 55℃ and a vacuum degree of -0.09MPa for 14h. The solid was then ground and passed through a 120-mesh sieve to obtain bromoalkyl-modified graphitic carbon nitride powder. Step S3: 1.5g of bromoalkyl-modified graphitic carbon nitride powder, 5g of 1-hexylimidazole and 37.5mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 65℃ and 300r / min for 24h. After the reaction was completed, the mixture was cooled to room temperature, and the solid product was collected by vacuum filtration. The solid product was washed 8 times with petroleum ether, and then washed once with anhydrous ethanol after vacuum filtration. The solid product was then placed in a vacuum drying oven and dried at 55℃ and -0.09MPa for 10h. The solid product was then ground and passed through a 120-mesh sieve to obtain the antistatic agent. Step S4: Add 10g of hollow glass microsphere powder and 100mL of 3mol / L sodium hydroxide solution to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen for protection and stir for 20min at 75℃ and 300r / min. Then transfer to an ultrasonic cleaner and sonicate for 20min at 300W. Collect the solid product by filtration and wash repeatedly with deionized water until the filtrate is neutral. Then place it in a vacuum drying oven and dry for 6h at 75℃ and -0.09MPa. Grind and pass through a 100-mesh sieve to obtain pretreated hollow glass microspheres. Step S5: Add 2.9g of cobalt nitrate hexahydrate, 8g of ferric nitrate nonahydrate, 4.2g of citric acid, and 50mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and a stirring rate of 200r / min for 20min. Then, sonicate at 300W for 20min. While stirring, add 25% ammonia solution dropwise to adjust the pH to 7. Add 1g of pretreated hollow glass microspheres and continue sonicating for 20min. The flask was placed in a constant temperature water bath at 80℃ and stirred for 2 hours. After being removed and allowed to stand at room temperature for 2 hours, it was then transferred to a constant temperature oven at 120℃ and dried for 24 hours to obtain a dry gel. The dry gel was crushed and transferred to a muffle furnace and heated to 600℃ at a heating rate of 5℃ / min. It was calcined for 4 hours, allowed to cool naturally to room temperature, washed once with distilled water, filtered, and placed in a vacuum drying oven. It was dried for 2 hours at a temperature of 75℃ and a vacuum degree of -0.09MPa. After that, it was ball-milled for 30 minutes and ground through a 120-mesh sieve to obtain cobalt ferrite-coated hollow glass microspheres. Step S6: Weigh out 50 parts wood powder, 250 parts sodium hydroxide aqueous solution, 2 parts antistatic agent, 20 parts high-density polyethylene, 8 parts maleic anhydride graft compatibilizer, 1 part antioxidant, 2 parts 2-hydroxy-4-methoxybenzophenone, 1 part γ-aminopropyltriethoxysilane, and 5 parts cobalt ferrite-coated hollow glass microspheres according to the following weight proportions, and set aside for later use; Step S7: Soak the wood flour (pine wood flour with a particle size of 100 mesh) in a sodium hydroxide aqueous solution (sodium hydroxide aqueous solution with a mass fraction of 5%) for 2 hours, then wash it with deionized water until neutral, centrifuge it at 800 r / min for 5 minutes, then put it in a vacuum drying oven and dry it at 100℃ and -0.09 MPa for 4 hours. Grind it and pass it through a 100-mesh standard sieve to obtain modified wood flour. Step S8: Place the antistatic agent and 1 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical) into a high-speed mixer and mix for 10 minutes at a temperature of 55℃ and a speed of 60r / min. Then feed it into a twin-screw extruder with a barrel temperature of 160℃, a die temperature of 170℃, and a screw speed of 30r / min. After extrusion, cool and crush the material and pass it through a 100-mesh sieve to obtain antistatic masterbatch. Step S9: Modified wood flour, 2 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical), maleic anhydride graft compatibilizer (FUSABOND® E265), antioxidant (antioxidant 1010), 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane are added to a high-speed mixer and mixed for 15 minutes at 60°C and 60 rpm. The temperature is then lowered to 40°C, and antistatic masterbatch is added. The mixture is mixed for 10 minutes, then fed into a twin-screw extruder. Vacuum degassing is activated on the twin screws, and cobalt ferrite-coated hollow glass microspheres are fed through the side of the twin screws. The material is fed separately through the inlet. The barrel temperature is 160℃, the die temperature is 170℃, and the screw speed is 30r / min. After extrusion, the material is cooled and crushed, and then fed into a single-screw extruder for secondary melt extrusion molding. The length-to-diameter ratio is 25:1, the barrel temperature is 170℃, the die temperature is 180℃, the feed speed is 20Hz, and the main machine speed is 30Hz. After gradient cooling and shaping (80℃→50℃→room temperature), the material is traction-cut to obtain an antistatic lightweight wood-plastic composite material.

[0023] Example 2:

[0024] This embodiment describes a method for preparing an antistatic lightweight wood-plastic composite material, including the following steps: Step S1: Place 6g of melamine in an agate mortar and grind for 21min. Then place it in a muffle furnace and heat it to 550℃ at a heating rate of 5℃ / min. Calcinate at a constant temperature for 4h. After calcination, allow it to cool naturally to room temperature. Grind it in an agate mortar and pass it through a 100-mesh standard sieve to obtain graphite phase carbon nitride powder. Step S2: 2.5g of graphitic carbon nitride powder, 35.2g of 1,4-dibromobutane, 50mL of dimethyl sulfoxide, and 0.25g of potassium carbonate were added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and reflux condenser. Nitrogen gas was introduced for protection, and the mixture was stirred at 27℃ and a stirring rate of 350r / min for 33min. Then, the temperature was raised to 87℃ and the mixture was stirred for 24.5h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The solid product was then collected by vacuum filtration. It was first ultrasonically washed 10 times with petroleum ether, with each ultrasonic power of 300W and time of 10min. After vacuum filtration, it was washed twice with anhydrous ethanol. The solid was placed in a vacuum drying oven and dried at 57℃ and a vacuum degree of -0.09MPa for 14.5h. The solid was then ground and passed through a 120-mesh sieve to obtain bromoalkyl-modified graphitic carbon nitride powder. Step S3: 1.8g of bromoalkyl-modified graphitic carbon nitride powder, 6g of 1-hexylimidazole and 45mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 67℃ and 350r / min for 24h. After the reaction was completed, the mixture was cooled to room temperature, and the solid product was collected by vacuum filtration. The solid product was washed 8 times with petroleum ether, and then washed once with anhydrous ethanol after vacuum filtration. The solid product was then placed in a vacuum drying oven and dried at 57℃ and -0.09MPa for 11h. The solid product was then ground and passed through a 120-mesh sieve to obtain the antistatic agent. Step S4: Add 11g of hollow glass microsphere powder and 110mL of 3mol / L sodium hydroxide solution to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen for protection and stir for 23min at 77℃ and 350r / min. Then transfer to an ultrasonic cleaner and sonicate for 21min at 300W. Collect the solid product by filtration and wash repeatedly with deionized water until the filtrate is neutral. Then place it in a vacuum drying oven and dry for 6.5h at 77℃ and -0.09MPa. Grind and pass through a 100-mesh sieve to obtain pretreated hollow glass microspheres. Step S5: Add 4.35g of cobalt nitrate hexahydrate, 12g of ferric nitrate nonahydrate, 6.3g of citric acid, and 75mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 27℃ and a stirring rate of 230r / min for 25min. Then, sonicate at 300W for 21min. While stirring, add 25% ammonia solution dropwise to adjust the pH to 7. Add 1.5g of pretreated hollow glass microspheres and continue sonicating for 21min. The flask was placed in a constant temperature water bath at 80℃ and stirred for 2.5h. After being removed and allowed to stand at room temperature for 2h, it was transferred to a constant temperature oven at 120℃ and dried for 24h to obtain a dry gel. The dry gel was crushed and transferred to a muffle furnace and heated to 600℃ at a heating rate of 5℃ / min for 4h. After being naturally cooled to room temperature, it was washed once with distilled water, filtered, and placed in a vacuum drying oven. It was dried for 2.5h at a temperature of 77℃ and a vacuum degree of -0.09MPa. Then it was ball-milled for 31min and ground through a 120-mesh sieve to obtain cobalt ferrite-coated hollow glass microspheres. Step S6: Weigh out 60 parts by weight of wood flour, 325 parts by weight of sodium hydroxide aqueous solution, 3.5 parts by weight of antistatic agent, 30 parts by weight of high-density polyethylene, 11.5 parts by weight of maleic anhydride graft compatibilizer, 2 parts by weight of antioxidant, 3.5 parts by weight of 2-hydroxy-4-methoxybenzophenone, 1.5 parts by weight of γ-aminopropyltriethoxysilane, and 7.5 parts by weight of cobalt ferrite-coated hollow glass microspheres, and set aside. Step S7: Soak the wood flour (pine wood flour with a particle size of 100 mesh) in a sodium hydroxide aqueous solution (sodium hydroxide aqueous solution with a mass fraction of 5%) for 2 hours, then wash it with deionized water until neutral, centrifuge it at 900 r / min for 7 minutes, then put it in a vacuum drying oven and dry it at 103℃ and -0.09 MPa for 4.5 hours. Grind it and pass it through a 100-mesh standard sieve to obtain modified wood flour. Step S8: The antistatic agent and 1 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical) are placed in a high-speed mixer and mixed for 11 minutes at a temperature of 57°C and a speed of 72 r / min. Then, the mixture is fed into a twin-screw extruder with a barrel temperature of 170°C, a die temperature of 177°C, and a screw speed of 30 r / min. After extrusion, the mixture is cooled, crushed, and passed through a 100-mesh sieve to obtain antistatic masterbatch. Step S9: Modified wood flour, 2 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical), maleic anhydride graft compatibilizer (FUSABOND® E265), antioxidant (antioxidant 1010), 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane are added to a high-speed mixer and mixed for 20 minutes at 70°C and 72 r / min. The temperature is then lowered to 45°C, and antistatic masterbatch is added. The mixture is mixed for 13 minutes, then fed into a twin-screw extruder. Vacuum degassing is activated on the twin screws, and cobalt ferrite-coated hollow glass microspheres are fed through the side of the twin screws. The feed is added separately at the inlet, the barrel temperature is 175℃, the die temperature is 185℃, and the screw speed is 35r / min. After extrusion, it is cooled and crushed, and then fed into a single screw extruder for secondary melt extrusion molding with a length-to-diameter ratio of 25:1, a barrel temperature of 187℃, a die temperature of 195℃, a feed speed of 30Hz, and a main machine speed of 40Hz. After gradient cooling and shaping (80℃→50℃→room temperature), it is traction-cut to obtain an antistatic lightweight wood-plastic composite material.

[0025] Example 3:

[0026] This embodiment describes a method for preparing an antistatic lightweight wood-plastic composite material, including the following steps: Step S1: Place 7g of melamine in an agate mortar and grind for 22min. Then place it in a muffle furnace and heat it to 550℃ at a heating rate of 5℃ / min. Calcinate at a constant temperature for 4h. After calcination, allow it to cool naturally to room temperature. Grind it in an agate mortar and pass it through a 100-mesh standard sieve to obtain graphite phase carbon nitride powder. Step S2: Add 3g of graphitic carbon nitride powder, 42.2g of 1,4-dibromobutane, 60mL of dimethyl sulfoxide, and 0.3g of potassium carbonate to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and reflux condenser. Purge with nitrogen for protection and stir at 30℃ and 400r / min for 35min. Then raise the temperature to 90℃ and stir for 25h. After the reaction is complete, allow it to cool naturally to room temperature. Collect the solid product by vacuum filtration. Wash it 10 times with petroleum ether using ultrasonication, each time with a power of 300W and a time of 10min. Then filter it and wash it twice with anhydrous ethanol. Place the solid in a vacuum drying oven and dry it for 15h at 60℃ and a vacuum of -0.09MPa. Grind and pass it through a 120-mesh sieve to obtain bromoalkyl-modified graphitic carbon nitride powder. Step S3: 2.1g of bromoalkyl-modified graphitic carbon nitride powder, 7g of 1-hexylimidazole and 52.5mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 70℃ and 400r / min for 24h. After the reaction was completed, the mixture was cooled to room temperature, and the solid product was collected by vacuum filtration. The solid product was washed 8 times with petroleum ether, and then washed once with anhydrous ethanol after vacuum filtration. The solid product was then placed in a vacuum drying oven and dried at 60℃ and -0.09MPa for 12h. The solid product was then ground and passed through a 120-mesh sieve to obtain the antistatic agent. Step S4: Add 12g of hollow glass microsphere powder and 120mL of 3mol / L sodium hydroxide solution to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen for protection and stir for 25min at 80℃ and 400r / min. Then transfer to an ultrasonic cleaner and sonicate for 22min at 300W. Collect the solid product by filtration and wash repeatedly with deionized water until the filtrate is neutral. Then place it in a vacuum drying oven and dry for 7h at 80℃ and -0.09MPa. Grind and pass through a 100-mesh sieve to obtain pretreated hollow glass microspheres. Step S5: Add 5.8g of cobalt nitrate hexahydrate, 16g of ferric nitrate nonahydrate, 8.4g of citric acid, and 100mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 30℃ and a stirring rate of 250r / min for 30min. Then, sonicate at 300W for 22min. While stirring, add 25% ammonia solution dropwise to adjust the pH to 7. Add 2g of pretreated hollow glass microspheres and continue sonicating for 22min. The three-necked flask was placed in a constant temperature water bath at 80℃ and stirred for 3 hours. After being removed and allowed to stand at room temperature for 2 hours, it was then transferred to a constant temperature oven at 120℃ and dried for 24 hours to obtain a dry gel. The dry gel was crushed and transferred to a muffle furnace, heated to 600℃ at a heating rate of 5℃ / min, and calcined for 4 hours. After naturally cooling to room temperature, it was washed twice with distilled water, filtered, and placed in a vacuum drying oven. It was dried for 3 hours at a temperature of 80℃ and a vacuum degree of -0.09MPa. Then, it was ball-milled for 32 minutes and ground through a 120-mesh sieve to obtain cobalt ferrite-coated hollow glass microspheres. Step S6: Weigh out 70 parts wood powder, 400 parts sodium hydroxide aqueous solution, 5 parts antistatic agent, 40 parts high-density polyethylene, 15 parts maleic anhydride graft compatibilizer, 3 parts antioxidant, 5 parts 2-hydroxy-4-methoxybenzophenone, 2 parts γ-aminopropyltriethoxysilane, and 10 parts cobalt ferrite-coated hollow glass microspheres according to the following weight proportions, and set aside for later use; Step S7: Soak the wood flour (pine wood flour with a particle size of 100 mesh) in a sodium hydroxide aqueous solution (sodium hydroxide aqueous solution with a mass fraction of 5%) for 2 hours, then wash it with deionized water until neutral, centrifuge it at 1000 r / min for 10 minutes, then put it in a vacuum drying oven and dry it at 105℃ and -0.09 MPa for 5 hours. Grind it and pass it through a 100-mesh standard sieve to obtain modified wood flour. Step S8: Place the antistatic agent and 1 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical) into a high-speed mixer and mix for 12 minutes at a temperature of 60℃ and a speed of 85r / min. Then feed it into a twin-screw extruder with a barrel temperature of 180℃, a die temperature of 185℃, and a screw speed of 30r / min. After extrusion, cool, crush, and pass through a 100-mesh sieve to obtain antistatic masterbatch. Step S9: Modified wood flour, 2 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical), maleic anhydride graft compatibilizer (FUSABOND® E265), antioxidant (antioxidant 1010), 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane are added to a high-speed mixer and mixed for 25 minutes at 80°C and 85 r / min. The temperature is then lowered to 50°C, and antistatic masterbatch is added. The mixture is mixed for 15 minutes, then fed into a twin-screw extruder. Vacuum degassing is activated on the twin screws, and cobalt ferrite-coated hollow glass microspheres are fed through the side of the twin screws. The feed is added separately at the inlet, the barrel temperature is 190℃, the die temperature is 200℃, and the screw speed is 40r / min. After extrusion, it is cooled and crushed, and then fed into a single screw extruder for secondary melt extrusion molding with a length-to-diameter ratio of 25:1, a barrel temperature of 205℃, a die temperature of 210℃, a feed speed of 40Hz, and a main machine speed of 50Hz. After gradient cooling and shaping (80℃→50℃→room temperature), it is traction-cut to obtain an antistatic lightweight wood-plastic composite material.

[0027] Comparative Example 1: This comparative example illustrates a method for preparing an antistatic lightweight wood-plastic composite material, comprising the following steps: Step S1: Add 10g of hollow glass microsphere powder and 100mL of 3mol / L sodium hydroxide solution to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen for protection and stir for 20min at 75℃ and 300r / min. Then transfer to an ultrasonic cleaner and sonicate for 20min at 300W. Collect the solid product by filtration and wash repeatedly with deionized water until the filtrate is neutral. Then place it in a vacuum drying oven and dry for 6h at 75℃ and -0.09MPa. Grind and pass through a 100-mesh sieve to obtain pretreated hollow glass microspheres. Step S2: Add 2.9g of cobalt nitrate hexahydrate, 8g of ferric nitrate nonahydrate, 4.2g of citric acid, and 50mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and a stirring rate of 200r / min for 20min. Then, sonicate at 300W for 20min. While stirring, add 25% ammonia solution dropwise to adjust the pH to 7. Add 1g of pretreated hollow glass microspheres and continue sonicating for 20min. The flask was placed in a constant temperature water bath at 80℃ and stirred for 2 hours. After being removed and allowed to stand at room temperature for 2 hours, it was then transferred to a constant temperature oven at 120℃ and dried for 24 hours to obtain a dry gel. The dry gel was crushed and transferred to a muffle furnace and heated to 600℃ at a heating rate of 5℃ / min. It was calcined for 4 hours, allowed to cool naturally to room temperature, washed once with distilled water, filtered, and placed in a vacuum drying oven. It was dried for 2 hours at a temperature of 75℃ and a vacuum degree of -0.09MPa. After that, it was ball-milled for 30 minutes and ground through a 120-mesh sieve to obtain cobalt ferrite-coated hollow glass microspheres. Step S3: Weigh out 50 parts wood powder, 250 parts sodium hydroxide aqueous solution, 15 parts high-density polyethylene, 8 parts maleic anhydride graft compatibilizer, 1 part antioxidant, 2 parts 2-hydroxy-4-methoxybenzophenone, 1 part γ-aminopropyltriethoxysilane, and 5 parts cobalt ferrite-coated hollow glass microspheres according to the following weight proportions, and set aside. Step S4: Soak the wood flour (pine wood flour with a particle size of 100 mesh) in a sodium hydroxide aqueous solution (sodium hydroxide aqueous solution with a mass fraction of 5%) for 2 hours, then wash it with deionized water until neutral, centrifuge it at 800 r / min for 5 minutes, then put it in a vacuum drying oven and dry it at 100℃ and -0.09 MPa for 4 hours. Grind it and pass it through a 100-mesh standard sieve to obtain modified wood flour. Step S5: Modified wood flour, high-density polyethylene (HDPE5000S, produced by Yanshan Petrochemical), maleic anhydride graft compatibilizer (FUSABOND® E265), antioxidant (antioxidant 1010), 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane are added to a high-speed mixer and mixed for 15 minutes at 60°C and 60 rpm. The temperature is then lowered to 40°C, and antistatic masterbatch is added. The mixture is mixed for 10 minutes, and then fed into a twin-screw extruder. Vacuum degassing is activated on the twin screws, and cobalt ferrite-coated hollow glass microspheres are fed through the side of the twin screws. The material is fed separately through the inlet. The barrel temperature is 160℃, the die temperature is 170℃, and the screw speed is 30r / min. After extrusion, the material is cooled and crushed, and then fed into a single-screw extruder for secondary melt extrusion molding. The length-to-diameter ratio is 25:1, the barrel temperature is 170℃, the die temperature is 180℃, the feed speed is 20Hz, and the main machine speed is 30Hz. After gradient cooling and shaping (80℃→50℃→room temperature), the material is traction-cut to obtain an antistatic lightweight wood-plastic composite material.

[0028] Comparative Example 2: This comparative example illustrates a method for preparing an antistatic lightweight wood-plastic composite material, comprising the following steps: Step S1: Place 5g of melamine in an agate mortar and grind for 20min. Then place it in a muffle furnace and heat it to 550℃ at a heating rate of 5℃ / min. Calcinate at a constant temperature for 4h. After calcination, allow it to cool naturally to room temperature. Grind it in an agate mortar and pass it through a 100-mesh standard sieve to obtain graphite phase carbon nitride powder. Step S2: 2g of graphitic carbon nitride powder, 28.1g of 1,4-dibromobutane, 40mL of dimethyl sulfoxide, and 0.2g of potassium carbonate were added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and reflux condenser. Nitrogen gas was introduced for protection, and the mixture was stirred at 25℃ and a stirring rate of 300r / min for 30min. Then the temperature was raised to 85℃ and the mixture was stirred for 24h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The solid product was then collected by vacuum filtration. It was first ultrasonically washed 10 times with petroleum ether, with each ultrasonic power of 300W and time of 10min. After vacuum filtration, it was washed twice with anhydrous ethanol. The solid was placed in a vacuum drying oven and dried at 55℃ and a vacuum degree of -0.09MPa for 14h. The solid was then ground and passed through a 120-mesh sieve to obtain bromoalkyl-modified graphitic carbon nitride powder. Step S3: 1.5g of bromoalkyl-modified graphitic carbon nitride powder, 5g of 1-hexylimidazole and 37.5mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 65℃ and 300r / min for 24h. After the reaction was completed, the mixture was cooled to room temperature, and the solid product was collected by vacuum filtration. The solid product was washed 8 times with petroleum ether, and then washed once with anhydrous ethanol after vacuum filtration. The solid product was then placed in a vacuum drying oven and dried at 55℃ and -0.09MPa for 10h. The solid product was then ground and passed through a 120-mesh sieve to obtain the antistatic agent. Step S4: Weigh out 50 parts wood powder, 250 parts sodium hydroxide aqueous solution, 2 parts antistatic agent, 20 parts high-density polyethylene, 8 parts maleic anhydride graft compatibilizer, 1 part antioxidant, 2 parts 2-hydroxy-4-methoxybenzophenone and 1 part γ-aminopropyltriethoxysilane according to the weight ratio, and set aside. Step S5: Soak the wood flour (pine wood flour with a particle size of 100 mesh) in a sodium hydroxide aqueous solution (sodium hydroxide aqueous solution with a mass fraction of 5%) for 2 hours, then wash it with deionized water until neutral, centrifuge it at 800 r / min for 5 minutes, then put it in a vacuum drying oven and dry it at 100℃ and -0.09 MPa for 4 hours. Grind it and pass it through a 100-mesh standard sieve to obtain modified wood flour. Step S6: Place the antistatic agent and 1 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical) into a high-speed mixer and mix for 10 minutes at a temperature of 55℃ and a speed of 60r / min. Then feed it into a twin-screw extruder with a barrel temperature of 160℃, a die temperature of 170℃, and a screw speed of 30r / min. After extrusion, cool and crush the material and pass it through a 100-mesh sieve to obtain antistatic masterbatch. Step S7: Add modified wood flour, 2 / 3 high-density polyethylene (HDPE 5000S produced by Yanshan Petrochemical), and maleic anhydride graft compatibilizer (FUSABOND®). E265), antioxidant (antioxidant type: antioxidant 1010), 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane were added to a high-speed mixer and mixed for 15 minutes at 60°C and 60 r / min. The temperature was then lowered to 40°C, and antistatic masterbatch was added and mixed for 10 minutes. The mixture was then fed into a twin-screw extruder with vacuum degassing. The barrel temperature was 160°C, the die temperature was 170°C, and the screw speed was 30 r / min. After extrusion, the mixture was cooled and crushed, and then fed into a single-screw extruder for secondary melt extrusion molding with a length-to-diameter ratio of 25:1. The barrel temperature was 170°C, the die temperature was 180°C, the feed speed was 20 Hz, and the main extruder speed was 30 Hz. After gradient cooling and shaping (80°C → 50°C → room temperature), the mixture was traction-cut to obtain an antistatic lightweight wood-plastic composite material.

[0029] Comparative Example 3: This comparative example illustrates a method for preparing an antistatic lightweight wood-plastic composite material, comprising the following steps: Step S1: Weigh out 50 parts wood flour, 250 parts sodium hydroxide aqueous solution, 15 parts high-density polyethylene, 8 parts maleic anhydride graft compatibilizer, 1 part antioxidant, 2 parts 2-hydroxy-4-methoxybenzophenone and 1 part γ-aminopropyltriethoxysilane according to the weight ratio, and set aside. Step S2: Soak the wood flour (pine wood flour with a particle size of 100 mesh) in a sodium hydroxide aqueous solution (sodium hydroxide aqueous solution with a mass fraction of 5%) for 2 hours, then wash it with deionized water until neutral, centrifuge it at 800 r / min for 5 minutes, then put it in a vacuum drying oven and dry it at 100℃ and -0.09 MPa for 4 hours. Grind it and pass it through a 100-mesh standard sieve to obtain modified wood flour. Step S3: Add modified wood flour, high-density polyethylene (HDPE5000S, produced by Yanshan Petrochemical), and maleic anhydride graft compatibilizer (FUSABOND®). E265), antioxidant (antioxidant type: antioxidant 1010), 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane were added to a high-speed mixer and mixed for 15 minutes at 60°C and 60 r / min. The temperature was then lowered to 40°C, and antistatic masterbatch was added and mixed for 10 minutes. The mixture was then fed into a twin-screw extruder with vacuum degassing. The barrel temperature was 160°C, the die temperature was 170°C, and the screw speed was 30 r / min. After extrusion, the mixture was cooled and crushed, and then fed into a single-screw extruder for secondary melt extrusion molding with a length-to-diameter ratio of 25:1. The barrel temperature was 170°C, the die temperature was 180°C, the feed speed was 20 Hz, and the main extruder speed was 30 Hz. After gradient cooling and shaping (80°C → 50°C → room temperature), the mixture was traction-cut to obtain an antistatic lightweight wood-plastic composite material.

[0030] Performance testing: The antistatic lightweight wood-plastic composite materials of Examples 1-3 and Comparative Examples 1-3 were tested according to the following methods; Volume resistivity test: The test was conducted according to GB / T 31838.2-2019 "Dielectric and resistive properties of solid insulating materials - Part 2: Resistive properties (DC method) - Volume resistivity and volume resistivity"; the sample size was 100mm × 100mm × 4mm; a high-resistivity meter was used with a three-electrode system; the electrodes were uniformly attached to the sample surface, and a DC 500V test voltage was applied; after standing for 2 minutes to allow the current to stabilize, the volume resistivity value was read; the volume resistivity was calculated according to the formula ρv = Rv × S / d (Rv is the volume resistivity, S is the electrode area, and d is the sample thickness); each sample was tested 3 times, and the average value was taken.

[0031] Density test: The test was conducted according to GB / T 1033.1-2008 "Determination of density of non-foamed plastics - Part 1: Immersion method, liquid pyrometer method and titration method"; the sample size was 20mm × 20mm × 4mm; the water displacement method was used, with an electronic balance accuracy of 0.0001g. Beakers, glass rods, and distilled water were prepared. First, the mass of the sample in air (m1) was weighed, accurate to 0.0001g. The sample was then completely immersed in distilled water at 25℃, avoiding contact between the sample and the bottom and side walls of the beaker. The mass of the sample in water (m2) was then weighed. The mass was calculated using the formula ρ = m1 / (m1-m2) × ρwater (ρwater = 1.000g / cm³). 3 Calculate the density, test 3 samples in parallel, and take the average value.

[0032] Bending strength test: The test was conducted in accordance with GB / T 9341-2008 "Determination of bending properties of plastics"; the sample size was 80mm×10mm×4mm; a universal testing machine was used, the test rate was 2mm / min, the span was 64mm (span = sample thickness × 16), the sample was placed stably on the test support to ensure uniform force and avoid sample displacement, a uniform load was applied until the sample broke or the deformation reached the specified value, the maximum load was recorded, the bending strength was calculated according to the formula, 5 samples were tested in parallel, and the average value was taken after removing outliers.

[0033] Impact strength test of simply supported beam: The test was conducted in accordance with GB / T 1043.1-2008 "Determination of impact properties of simply supported beams of plastics - Part 1: Non-instrumental impact test"; the sample size was 80mm×10mm×4mm; a simply supported beam impact testing machine was used, with a pendulum energy of 2J, an impact velocity of 3.5m / s, and a span of 60mm. The sample was fixed on the impact support, ensuring that the sample and the support were in close contact. The impact direction was perpendicular to the sample surface. The pendulum was released, and the midpoint of the sample was impacted. The impact energy absorbed was recorded. Five samples were tested in parallel. Samples with irregular fracture were discarded, and the average impact strength of the remaining samples was calculated.

[0034] Water absorption rate test: The test was conducted according to GB / T 1034-2008 "Determination of water absorption of plastics"; the sample size was 20mm×20mm×4mm, vacuum dried at 105℃ to constant weight, with no pores on the surface, and the mass of the dried sample (m0) was weighed to an accuracy of 0.0001g. The sample was completely immersed in distilled water at 25℃, with the water level 10mm above the sample surface to prevent the sample from floating. After soaking for 24h, the sample was removed, and the surface moisture was quickly absorbed with filter paper. The mass of the sample (m1) was weighed immediately. The water absorption rate was calculated according to the formula W=(m1-m0) / m0×100%. Three samples were tested in parallel, and the average value was taken.

[0035] The test results are shown in Table 1: Table 1: Test Results Summary Table

[0036] Referring to Table 1, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the antistatic lightweight wood-plastic composite material has excellent antistatic properties, low density and lightweight characteristics, good bending strength and impact strength, and low water absorption and excellent water resistance.

[0037] Based on the comparison between Example 1 and Comparative Example 1, it can be seen that the volume resistivity in Comparative Example 1 reaches 9.2 × 10⁻⁶. 14The concentration (Ω·m) was more than 6 orders of magnitude higher than that of Example 1, and the antistatic properties were basically lost, proving that the modified imidazolium salt grafted graphite phase carbon nitride is the core component that imparts antistatic function to the composite material; the density was slightly higher than that of Example 1, and the porosity inside the matrix increased slightly due to the lack of antistatic agent filling effect; the mechanical properties and water absorption rate were slightly worse than those of Example 1, and the overall performance fluctuation was small, indicating that the antistatic agent has a limited impact on the mechanical properties of the composite material.

[0038] Based on the comparison between Example 1 and Comparative Example 2, it can be seen that the volume resistivity in Comparative Example 2 reaches 2.1 × 10⁻⁶. 9 (Ω·m) still has certain antistatic properties, indicating that the effect of the antistatic agent is not affected by the microsphere coating state; the density is slightly lower than that of Example 1 because the hollow structure of the uncoated hollow glass microspheres is more complete, but the bending strength and impact strength decrease respectively, and the water absorption rate increases. This is because the surface of the untreated hollow glass microspheres has no active hydroxyl groups, and the interfacial bonding force with the polymer matrix is ​​extremely poor. When subjected to force, stress concentration is easily generated, and the interfacial gaps are easy to become water penetration channels. This proves that cobalt ferrite coating is the key to improving the mechanical properties and water resistance of composite materials.

[0039] Based on the comparison between Example 1 and Comparative Example 3, it can be seen that the volume resistivity in Comparative Example 3 reaches 1.1 × 10⁻⁶. 16 (Ω·m) indicates the worst antistatic performance among all samples, reflecting the decisive impact of the lack of antistatic agent. Mechanical properties deteriorate across the board, with both flexural strength and impact strength decreasing. Due to the simultaneous lack of filling effect from antistatic agent and interfacial reinforcement effect from cobalt ferrite, internal defects in the matrix increase significantly. The water absorption rate reaches 5.8%, and the dual defects make it easy for moisture to penetrate into the material. This fully demonstrates that the synergistic effect of antistatic agent and cobalt ferrite-coated hollow glass microspheres is crucial for improving the overall performance of composite materials.

[0040] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. An antistatic lightweight wood-plastic composite material, characterized in that, Includes the following components by weight: 50-70 parts wood flour, 250-400 parts sodium hydroxide aqueous solution, 2-5 parts antistatic agent, 20-40 parts high-density polyethylene, 8-15 parts maleic anhydride graft compatibilizer, 1-3 parts antioxidant, 2-5 parts 2-hydroxy-4-methoxybenzophenone, 1-2 parts γ-aminopropyltriethoxysilane, and 5-10 parts cobalt ferrite-coated hollow glass microspheres. The antistatic agent is prepared by the following steps: Step a1: Grind melamine, then calcine it in a muffle furnace, cool it, grind it again, and sieve it to obtain graphitic carbon nitride powder; Step a2: Add graphitic carbon nitride powder, 1,4-dibromobutane, dimethyl sulfoxide and potassium carbonate to a three-necked flask and stir to react. Then heat and stir to react, cool, filter, wash ultrasonically, filter again, wash, dry, grind and sieve to obtain bromoalkyl modified graphitic carbon nitride powder. Step a3: Add bromoalkyl-modified graphitic carbon nitride powder, 1-hexylimidazole and dimethyl sulfoxide to a three-necked flask and stir to react. Cool, filter, wash, filter again, wash again, dry, grind and sieve to obtain the antistatic agent.

2. The antistatic lightweight wood-plastic composite material according to claim 1, characterized in that, The ratio of graphitic carbon nitride powder, 1,4-dibromobutane, dimethyl sulfoxide, and potassium carbonate used in step a2 is 2-3g. 28.1-42.2g: 40-60mL: 0.2-0.3g.

3. The antistatic lightweight wood-plastic composite material according to claim 1, characterized in that, In step a3, the ratio of the bromoalkyl-modified graphitic carbon nitride powder, 1-hexylimidazole, and dimethyl sulfoxide is 1.5-2.1 g: 5-7 g: 37.5-52.5 mL.

4. The antistatic lightweight wood-plastic composite material according to claim 1, characterized in that, The cobalt ferrite-coated hollow glass microspheres were prepared by the following steps: Step b1: Add hollow glass microsphere powder and sodium hydroxide solution to a three-necked flask and stir to react. Then, sonicate, filter, wash, dry, grind and sieve to obtain pretreated hollow glass microspheres. Step b2: Cobalt nitrate hexahydrate, ferric nitrate nonahydrate, citric acid, and deionized water were added to a three-necked flask and stirred to react. Then, the mixture was sonicated, and ammonia was added dropwise to adjust the pH of the solution to 7. Pretreated hollow glass microspheres were added, and sonication was continued. After stirring, the mixture was allowed to stand and dried to obtain a dry gel. The dry gel was crushed, calcined, cooled, washed, filtered, and dried. Then, it was ball-milled, ground, and sieved to obtain cobalt ferrite-coated hollow glass microspheres.

5. The antistatic lightweight wood-plastic composite material according to claim 4, characterized in that, In step b1, the ratio of hollow glass microsphere powder to sodium hydroxide solution is 10-12g:100-120mL; the concentration of sodium hydroxide solution is 3mol / L.

6. The antistatic lightweight wood-plastic composite material according to claim 4, characterized in that, In step b2, the ratio of cobalt nitrate hexahydrate, ferric nitrate nonahydrate, citric acid, deionized water, and pretreated hollow glass microspheres is 2.9-5.8g: 8-16g: 4.2-8.4g: 50-100mL: 1-2g; the mass fraction of the ammonia water is 25%.

7. A method for preparing an antistatic lightweight wood-plastic composite material, characterized in that, The method for preparing the antistatic lightweight wood-plastic composite material as described in any one of claims 1-6 includes the following steps: Step 1: Weigh out 50-70 parts by weight of wood flour, 250-400 parts by weight of sodium hydroxide aqueous solution, 2-5 parts by weight of antistatic agent, 20-40 parts by weight of high-density polyethylene, 8-15 parts by weight of maleic anhydride graft compatibilizer, 1-3 parts by weight of antioxidant, 2-5 parts by weight of 2-hydroxy-4-methoxybenzophenone, 1-2 parts by weight of γ-aminopropyltriethoxysilane, and 5-10 parts by weight of cobalt ferrite-coated hollow glass microspheres, and set aside. Step 2: Soak the wood flour in an aqueous sodium hydroxide solution, then wash, centrifuge to dehydrate, dry, grind, and sieve to obtain modified wood flour; Step 3: Mix the antistatic agent and 1 / 3 high-density polyethylene, then feed it into a twin-screw extruder. After extrusion, cool, crush, and sieve to obtain antistatic masterbatch. Step 4: Modified wood flour, 2 / 3 high-density polyethylene, maleic anhydride graft compatibilizer, antioxidant, 2-hydroxy-4-methoxybenzophenone, and γ-aminopropyltriethoxysilane are added to a high-speed mixer and mixed. Then the temperature is reduced, and antistatic masterbatch is added and mixed. The mixture is then fed into a twin-screw extruder. Cobalt ferrite-coated hollow glass microspheres are added separately through the side feed port of the twin screw. After extrusion, the mixture is cooled and crushed, and then fed into a single-screw extruder for secondary melt extrusion molding. After gradient cooling and shaping, the mixture is traction-cut to obtain an antistatic lightweight wood-plastic composite material.

8. The method for preparing an antistatic lightweight wood-plastic composite material according to claim 7, characterized in that, The wood flour mentioned in step one is pine wood flour with a particle size of 100 mesh; the sodium hydroxide aqueous solution has a mass fraction of 5%.

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