Antibacterial flame-retardant environment-friendly wood-plastic material, preparation method thereof and application thereof on cover plate

Abstract

The application discloses an antibacterial and flame-retardant environment-friendly wood-plastic material and a preparation method and application to a cover plate thereof, and relates to the technical field of non-metal additive materials.The antibacterial and flame-retardant environment-friendly wood-plastic material comprises the following raw materials in parts by weight: 40-60 parts of polyethylene, 30-40 parts of straw powder, 5-10 parts of nano titanium dioxide, 1-3 parts of a lubricant, 1-3 parts of a compatilizer, 0.8-1.8 parts of an antibacterial agent, 2-5 parts of a flame retardant, and 1-2 parts of a foaming agent.The antibacterial and flame-retardant environment-friendly wood-plastic material prepared by the application has good flame-retardant performance and antibacterial performance.

Description

Technical Field

[0001] This invention relates to the field of non-metallic additive materials technology, specifically to an antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material, its preparation method, and its application in cover plates. Background Technology

[0002] With increasing global awareness of environmental protection and higher requirements for sustainable development, wood-plastic composites, a new type of environmentally friendly material made by combining waste wood fibers with a plastic matrix, have found applications in building decoration, outdoor facilities, and municipal engineering due to their advantages such as resource conservation, light weight, corrosion resistance, and good processing performance. As an indispensable sealing component for containers such as storage barrels and logistics turnover boxes, lids are constantly exposed to complex environments involving humidity, temperature fluctuations, and microbial growth, placing higher demands on the material's mechanical strength, flame retardancy, and antibacterial properties. However, traditional wood-plastic materials have several drawbacks: firstly, their flame retardancy is insufficient, easily igniting and releasing large amounts of smoke and harmful gases when exposed to fire, making it difficult to meet modern building fire safety standards; secondly, the porous structure of wood-plastic materials makes them highly susceptible to moisture absorption in humid environments, leading to mold growth, which not only affects aesthetics but also accelerates material aging and degradation, significantly shortening their service life.

[0003] With the continuous advancement of technology and the development of materials engineering, wood-plastic composite lids can be efficiently manufactured using 3D printing technology. This process uses wood-plastic composite materials as non-metallic additives and adopts a layer-by-layer additive manufacturing mode, enabling rapid and precise molding of bucket lids. This technology eliminates the need for mold making and complex machining, significantly shortening the transformation cycle from design to production, reducing the manufacturing cost of small-batch customized products, and greatly improving the adaptability and flexibility of personalized container lids.

[0004] Chinese invention patent CN105968862A discloses a novel environmentally friendly flame-retardant wood-plastic composite material. The components of this wood-plastic composite material include: 34-55 parts of pine wood powder, 25-34 parts of sorghum straw powder, 9-10 parts of pumpkin vine powder, 7-9 parts of woven bag plastic granules, 6-8 parts of filler, 4-6 parts of synthetic agent, 1-2 parts of lubricant, 1-2 parts of mildew-proof and antibacterial agent, 1-2 parts of desiccant, 2-4 parts of flame retardant, 2-4 parts of smoke suppressant, and 6-10 parts of adhesive. The wood-plastic composite material prepared by this invention has good flame retardant effect and stable and reliable performance, but its antibacterial properties need to be improved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide an antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material, its preparation method, and its application in cover plates.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material, comprising the following raw materials in parts by weight: Polyethylene 40-60 parts, straw powder 30-40 parts, nano titanium dioxide 5-10 parts, lubricant 1-3 parts, compatibilizer 1-3 parts, antibacterial agent 0.8-1.8 parts, flame retardant 2-5 parts, foaming agent 1-2 parts; The antibacterial agent is prepared by the following method: S1: 11-Dodecenol reacts with 6-carboxyhexyltriphenylphosphonium bromide to generate intermediate 1. S2: Intermediate 1 reacts with 4-aminobenzylthiophenol to generate intermediate 2. S3: Intermediate 2 reacts with 1H-pyrazole-1-formamidinium hydrochloride to generate an antibacterial agent.

[0007] In step S1, the molar ratio of 11-dodecenol to 6-carboxyhexyltriphenylphosphonium bromide is 1:(1.02-1.05).

[0008] In step S2, the molar ratio of intermediate 1 to 4-aminothiophenol is (1.05-1.1):1.

[0009] In step S3, the molar ratio of intermediate 2 to 1H-pyrazole-1-formamidinium hydrochloride is 1:(1.05-1.1).

[0010] The flame retardant is prepared by the following method: A1: Boric acid reacts with 1,3-diamino-2-propanol to form a hexaamino compound. A2: A hexaamino compound reacts with diethyl 4-chlorobutylphosphonate to form a hexaphosphate compound. A3: Hexaphosphate compounds react with γ-(2,3-epoxypropoxy)propyltrimethoxysilane to form flame retardants.

[0011] In step A1, the molar ratio of boric acid to 1,3-diamino-2-propanol is 1:3.03.

[0012] In step A2, the molar ratio of the hexaamino compound to diethyl 4-chlorobutylphosphonate is 1:6.05.

[0013] In step A3, the molar ratio of the hexaphosphate compound to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:6.05.

[0014] The lubricant is calcium stearate; the compatibilizer is maleic anhydride-grafted polyethylene; and the foaming agent is azodicarbonamide.

[0015] A method for preparing an antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material includes the following steps: (1) Weigh out the following by weight: 40-60 parts polyethylene, 30-40 parts straw powder, 5-10 parts nano titanium dioxide, 1-3 parts lubricant, 1-3 parts compatibilizer, 0.8-1.8 parts antibacterial agent, 2-5 parts flame retardant, and 1-2 parts foaming agent; (2) Polyethylene, straw powder, nano titanium dioxide, lubricant, compatibilizer, antibacterial agent, flame retardant and foaming agent are added to the mixing machine in sequence for melt mixing; then hot pressing and cold pressing are used to obtain antibacterial, flame retardant and environmentally friendly wood-plastic material.

[0016] Application of an antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material in cover plates.

[0017] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material prepared by this invention has good flame-retardant and antibacterial properties. Attached Figure Description

[0018] Figure 1 The 1H NMR spectrum of the antibacterial agent prepared in Example 1; Figure 2 Here is a high-resolution mass spectrum of the antibacterial agent prepared in Example 1; Figure 3 The 1H NMR spectrum of the flame retardant prepared in Example 4; Figure 4 The image shows a high-resolution mass spectrum of the flame retardant prepared in Example 4. Detailed Implementation

[0019] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0020] Example 1: Preparation of antibacterial agent: S1: Under nitrogen protection, 300 mL of dichloromethane, 0.102 mol of 6-carboxyhexyltriphenylphosphonium bromide, 0.11 mol of DCC (N,N'-dicyclohexylcarbodiimide), and 0.005 mol of DMAP (4-dimethylaminopyridine) were added to a reaction flask. The mixture was stirred for 10 min, and then 0.1 mol of 11-dodecenol was added. The reaction was carried out at room temperature for 6 h. After filtration, the mixture was rotary evaporated at 30 °C to constant weight. The mixture was purified by column chromatography (using a dichloromethane / methanol mixture containing 0.5% (v / v) triethylamine, with a dichloromethane / methanol volume ratio of 10:1 → 4:1 gradient elution). The mixture was rotary evaporated at 35 °C to constant weight and dried under vacuum at 40 °C for 12 h to obtain intermediate 1. The reaction equation is shown below:

[0021] Its 1H NMR spectrum data is as follows: 1H NMR (400 MHz, Chloroform- d ) δ 7.82 – 7.65 (m,15H), 5.87 – 5.69 (m, 1H), 5.19 – 4.90 (m, 2H), 4.11 (t, J = 6.2 Hz, 2H), 3.69 (t, J = 8.3 Hz, 2H), 2.31 (t, J = 8.5 Hz, 2H), 2.03 (tdt, J = 8.1, 6.8,1.4 Hz, 2H), 1.72 – 1.19 (m, 24H); HRMS (m / z): 557.3546[M-Br] + .

[0022] S2: Under nitrogen protection, add 350 ml of tetrahydrofuran, 0.105 mol of intermediate 1, 0.1 mol of 4-aminobenzylthiophenol, and 1.5 g of photoinitiator 184 to the reaction flask, stir and mix well, and at room temperature, at an intensity of 8.4 mW / cm². 2 After irradiation under a 365nm UV LED lamp for 2 hours, 200ml of ethyl acetate was added to the reaction mixture for dilution. The mixture was then washed successively with 150ml of 5wt% sodium bicarbonate solution and 100ml of saturated sodium chloride solution. The organic phase was dried over 20g of anhydrous sodium sulfate, filtered, and rotary evaporated at 45℃ to constant weight. 250ml of n-hexane was added, and the mixture was stirred at room temperature for 30 minutes to precipitate. The precipitate was filtered, washed with cold n-hexane (3×50ml), and dried under vacuum at 45℃ for 12 hours to obtain intermediate 2. The reaction equation is shown below:

[0023] Its 1H NMR spectrum data is as follows: 1 H NMR (400 MHz, DMSO- d 6 ) δ 7.84 – 7.63 (m, 15H), 7.11 – 7.04 (m, 2H), 6.67 – 6.60 (m, 2H), 4.59 (s, 2H), 4.07 (t, J = 6.2 Hz, 2H), 3.69 (t, J = 8.4 Hz, 2H), 2.88 (t, J = 6.2 Hz, 2H), 2.31 (t, J = 8.5 Hz, 2H), 1.69 – 1.22 (m, 28H); HRMS (m / z): 682.3846[M-Br] + .

[0024] S3: Under nitrogen protection, 400 ml of DMF (N,N-dimethylformamide) and 0.1 mol of intermediate 2 were added to the reaction flask and stirred until homogeneous. Then, 0.105 mol of 1H-pyrazole-1-formamidinium hydrochloride was added in 5 equal batches, with a 5-minute interval between batches. Next, 0.11 mol of N,N-diisopropylethylamine was added. The reaction was carried out at room temperature for 12 hours. The reaction solution was cooled to 0°C in an ice bath, and 500 ml of diethyl ether was slowly added while stirring. A precipitate formed; the precipitate was filtered, washed with 50 ml of cold diethyl ether, and dried under vacuum at 50°C for 12 hours to obtain the antibacterial agent. The reaction equation is shown below:

[0025] Its proton nuclear magnetic resonance spectrum is as follows Figure 3 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6 δ 7.84 – 7.75 (m, 6H), 7.72 – 7.65 (m, 10H), 7.62 (s, 1H), 7.30 – 7.21 (m, 4H), 5.60 (s, 2H), 4.07 (t, J = 6.2 Hz, 2H), 3.69 (t, J = 8.4 Hz, 2H), 2.88 (t, J = 6.2 Hz, 2H), 2.31 (t, J = 8.5 Hz, 2H), 1.69 – 1.19 (m, 28H); its high-resolution mass spectrum is shown below. Figure 4 As shown, HRMS (m / z): 724.4065 [M-Br] + .

[0026] Example 2: Preparation of antibacterial agent: S1: Under nitrogen protection, 300 ml of dichloromethane, 0.103 mol of 6-carboxyhexyltriphenylphosphonium bromide, 0.11 mol of DCC, and 0.005 mol of DMAP were added to the reaction flask. The mixture was stirred for 10 min, and then 0.1 mol of 11-dodecenol was added. The mixture was reacted at room temperature for 5 h. After filtration, the mixture was rotary evaporated at 30 °C to constant weight. The mixture was purified by column chromatography (using a dichloromethane / methanol mixture as eluent, containing 0.5% (v / v) triethylamine, with a dichloromethane / methanol volume ratio of 10:1 → 4:1 gradient elution). The mixture was rotary evaporated at 35 °C to constant weight and then vacuum dried at 40 °C for 12 h to obtain intermediate 1. S2: Under nitrogen protection, add 350 ml of tetrahydrofuran, 0.108 mol of intermediate 1, 0.1 mol of 4-aminobenzylthiophenol, and 1.5 g of photoinitiator 184 to the reaction flask, stir and mix well, and at room temperature, at an intensity of 8.4 mW / cm².2 After irradiation under a 365nm UV LED lamp for 2.5h, 200ml of ethyl acetate was added to the reaction mixture for dilution. The mixture was then washed successively with 150ml of 5wt% sodium bicarbonate solution and 100ml of saturated sodium chloride solution. The organic phase was dried over 20g of anhydrous sodium sulfate, filtered, and rotary evaporated at 45℃ to constant weight. 250ml of n-hexane was added, and the mixture was stirred at room temperature for 30min to precipitate. The precipitate was filtered, washed with cold n-hexane (3×50ml), and dried under vacuum at 45℃ for 12h to obtain intermediate 2. S3: Under nitrogen protection, add 400 ml DMF and 0.1 mol intermediate 2 to the reaction flask, stir and mix well, add 0.108 mol 1H-pyrazole-1-formamidin hydrochloride in 5 batches (5 min apart), then add 0.11 mol N,N-diisopropylethylamine, react at room temperature for 11 h, cool the reaction solution to 0 °C in an ice bath, slowly add 500 ml diethyl ether, stir, and precipitate; filter, wash with 50 ml cold diethyl ether, and vacuum dry at 50 °C for 12 h to obtain the antibacterial agent.

[0027] Example 3: Preparation of antibacterial agent: S1: Under nitrogen protection, 300 ml of dichloromethane, 0.105 mol of 6-carboxyhexyltriphenylphosphonium bromide, 0.11 mol of DCC and 0.005 mol of DMAP were added to the reaction flask. The mixture was stirred for 10 min, and then 0.1 mol of 11-dodecenol was added. The mixture was reacted at room temperature for 4 h. After filtration, the mixture was rotary evaporated at 30 °C to constant weight. The mixture was purified by column chromatography (the eluent was a dichloromethane / methanol mixture containing 0.5% (v / v) triethylamine, with a dichloromethane / methanol volume ratio of 10:1 → 4:1 gradient elution). The mixture was rotary evaporated at 35 °C to constant weight and then vacuum dried at 40 °C for 12 h to obtain intermediate 1. S2: Under nitrogen protection, add 350 ml of tetrahydrofuran, 0.11 mol of intermediate 1, 0.1 mol of 4-aminobenzylthiophenol, and 1.5 g of photoinitiator 184 to the reaction flask, stir and mix well, and at room temperature, at an intensity of 8.4 mW / cm². 2 After irradiation under a 365nm UV LED lamp for 3 hours, 200ml of ethyl acetate was added to the reaction mixture for dilution. The mixture was then washed successively with 150ml of 5wt% sodium bicarbonate solution and 100ml of saturated sodium chloride solution. The organic phase was dried over 20g of anhydrous sodium sulfate, filtered, and rotary evaporated at 45℃ to constant weight. 250ml of n-hexane was added, and the mixture was stirred at room temperature for 30 minutes to precipitate. The precipitate was filtered, washed with cold n-hexane (3×50ml), and dried under vacuum at 45℃ for 12 hours to obtain intermediate 2. S3: Under nitrogen protection, add 400 ml DMF and 0.1 mol intermediate 2 to the reaction flask, stir and mix well, add 0.11 mol 1H-pyrazole-1-formamidine hydrochloride in 5 batches (5 min apart), then add 0.11 mol N,N-diisopropylethylamine, react at room temperature for 10 h, cool the reaction solution to 0 °C in an ice bath, slowly add 500 ml diethyl ether, stir, and precipitate; filter, wash with 50 ml cold diethyl ether, and vacuum dry at 50 °C for 12 h to obtain the antibacterial agent.

[0028] Example 4: Preparation of flame retardant: A1: Add 100 ml toluene, 0.1 mol boric acid, and 0.303 mol 1,3-diamino-2-propanol to a reaction flask, stir to mix, and heat to 110 °C for 10 h (using a water separator to remove water during the reaction). After the reaction is complete, cool to room temperature, and rotary evaporate to constant weight at 60 °C. Slowly add 100 ml anhydrous diethyl ether, precipitate the solid, filter, wash with 50 ml anhydrous diethyl ether, and dry under vacuum at 35 °C for 12 h to obtain the hexaamino compound; the reaction equation is shown below:

[0029] Its 1H NMR data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 4.01 (p, J = 3.9Hz, 3H), 2.92 (dtd, J = 12.3, 5.9, 3.9 Hz, 6H), 2.67 (dtd, J = 12.3, 5.9, 3.9Hz, 6H), 1.32 (t, J = 5.9 Hz, 12H); HRMS (m / z): 279.2241[M+H] + .

[0030] A2: Under nitrogen protection, 500 ml of DMF, 0.605 mol of diethyl 4-chlorobutylphosphonate, and 0.1 mol of the hexaamino compound were stirred and mixed. Then, 0.012 mol of tetraethylammonium bromide and 0.61 mol of triethylamine were added. The mixture was heated to 70 °C and reacted for 4 h. After cooling to room temperature, the mixture was filtered, and the solution was rotary evaporated at 70 °C to constant weight. The solution was purified by silica gel column chromatography (using a mixture of dichloromethane and methanol containing 1% (v / v) acetic acid as the eluent, with a gradient elution ratio of 20:1 to 10:1). The solution was rotary evaporated at 50 °C to constant weight, and then dried under vacuum at 60 °C for 12 h to obtain the hexaphosphate compound. The reaction equation is shown below:

[0031] Its 1H NMR data are as follows:1 H NMR (400 MHz, Chloroform- d ) δ 4.24 (p, J = 4.4Hz, 3H), 4.10 (q, J = 7.2 Hz, 24H), 3.57 (tt, J = 5.9, 5.0 Hz, 6H), 2.89 –2.55 (m, 24H), 2.06 – 1.95 (m, 12H), 1.69 – 1.55 (m, 24H), 1.37 (t, J = 7.2Hz, 36H); HRMS (m / z): 1431.7736[M+H] + .

[0032] A3: Under nitrogen protection, 1000 ml of anhydrous tetrahydrofuran, 0.1 mol of a hexaphosphate compound, 0.605 mol of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 0.1 mol of triethylamine were stirred and mixed. The mixture was heated to 50 °C and reacted for 7 h. After cooling to room temperature, the mixture was filtered and rotary evaporated at 50 °C to constant weight. The final weight was determined by diluting the solution with 800 ml of a mixture of anhydrous ethyl acetate and n-hexane (V... 乙酸乙酯 :V 正己烷 The mixture of 8:2 (ratio of water to oxygen) was recrystallized and dried under vacuum at 50°C for 8 hours to obtain the flame retardant. The reaction equation is shown below:

[0033] Its proton nuclear magnetic resonance spectrum is as follows Figure 3 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 4.30 (p, J = 6.0 Hz, 3H), 4.10 (q, J = 7.2 Hz, 24H), 3.91 –3.80 (m, 6H), 3.68 (dd, J = 11.6, 5.7 Hz, 6H), 3.59 (s, 54H), 3.50 – 3.35 (m,24H), 2.87 (ddd, J = 16.9, 11.8, 6.0 Hz, 12H), 2.68 – 2.48 (m, 24H), 2.03 –1.94 (m, 12H), 1.71 – 1.56 (m, 36H), 1.37 (t, J = 7.2 Hz, 36H), 0.75 (t, J =9.8 Hz, 12H); its high-resolution mass spectrum is as follows: Figure 4 As shown, HRMS (m / z): 2849.4245M+H + .

[0034] Example 5: Preparation of antibacterial, flame-retardant, and environmentally friendly wood-plastic composite materials: (1) Weigh out: 400g polyethylene, 300g straw powder, 50g nano titanium dioxide, 10g lubricant (calcium stearate), 10g compatibilizer (maleic anhydride grafted polyethylene), 8g antibacterial agent (prepared in Example 1), 20g flame retardant (prepared in Example 4), and 10g foaming agent (azodicarbonamide); (2) Polyethylene, straw powder, nano titanium dioxide, lubricant, compatibilizer, antibacterial agent, flame retardant and foaming agent are added to the mixer in sequence for melt mixing (the high and low temperature rollers of the mixer are 170℃ and 160℃ respectively); after mixing, it is directly put into the hot press, heated to 180℃, and hot-pressed for 10 minutes at a pressure of 5MPa. After the hot pressing is completed, it is immediately cold-pressed and shaped, cooled to 50℃, and cold-pressed for 10 minutes at a pressure of 7MPa. After the cold pressing is completed, antibacterial, flame-retardant and environmentally friendly wood-plastic material is obtained.

[0035] Example 6: Preparation of antibacterial, flame-retardant, and environmentally friendly wood-plastic composite materials: (1) Weigh out: 500g polyethylene, 350g straw powder, 80g nano titanium dioxide, 20g lubricant (calcium stearate), 20g compatibilizer (maleic anhydride grafted polyethylene), 12g antibacterial agent (prepared in Example 2), 30g flame retardant (prepared in Example 4), and 15g foaming agent (azodicarbonamide); (2) Polyethylene, straw powder, nano titanium dioxide, lubricant, compatibilizer, antibacterial agent, flame retardant and foaming agent are added to the mixer in sequence for melt mixing (the high and low temperature rollers of the mixer are 170℃ and 160℃ respectively); after mixing, it is directly put into the hot press, heated to 180℃, and hot-pressed for 10 minutes at a pressure of 5MPa. After the hot pressing is completed, it is immediately cold-pressed and shaped, cooled to 50℃, and cold-pressed for 10 minutes at a pressure of 7MPa. After the cold pressing is completed, antibacterial, flame-retardant and environmentally friendly wood-plastic material is obtained.

[0036] Example 7: Preparation of antibacterial, flame-retardant, and environmentally friendly wood-plastic composite materials: (1) Weigh out: 600g polyethylene, 400g straw powder, 100g nano titanium dioxide, 30g lubricant (calcium stearate), 30g compatibilizer (maleic anhydride grafted polyethylene), 18g antibacterial agent (prepared in Example 3), 50g flame retardant (prepared in Example 4), and 20g foaming agent (azodicarbonamide); (2) Polyethylene, straw powder, nano titanium dioxide, lubricant, compatibilizer, antibacterial agent, flame retardant and foaming agent are added to the mixer in sequence for melt mixing (the high and low temperature rollers of the mixer are 170℃ and 160℃ respectively); after mixing, it is directly put into the hot press, heated to 180℃, and hot-pressed for 10 minutes at a pressure of 5MPa. After the hot pressing is completed, it is immediately cold-pressed and shaped, cooled to 50℃, and cold-pressed for 10 minutes at a pressure of 7MPa. After the cold pressing is completed, antibacterial, flame-retardant and environmentally friendly wood-plastic material is obtained.

[0037] Comparative Example 1 The raw material composition and preparation method of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material are basically the same as those in Example 6, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method: The preparation method of the antibacterial agent is basically the same as that in Example 2, except that 11-dodecenol in step S1 is replaced with an equimolar amount of 7-octen-1-ol.

[0038] Comparative Example 2 The raw material composition and preparation method of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material are basically the same as those in Example 6, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method: The preparation method of the antibacterial agent is basically the same as that in Example 2, except that the 6-carboxyhexyltriphenylphosphine bromide in step S1 is replaced with an equimolar amount of (3-propanoyl)triphenylphosphine bromide.

[0039] Comparative Example 3 The raw material composition and preparation method of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material are basically the same as those in Example 6, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method: The preparation method of the antibacterial agent is basically the same as that in Example 2, except that the 4-aminobenzylthiophenol in step S2 is replaced with an equimolar amount of 4-aminobutane-1-thiol.

[0040] Comparative Example 4 The raw material composition and preparation method of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material are basically the same as those in Example 6, except that the flame retardant is replaced with an equal weight of a flame retardant prepared by the following method: The preparation method of the flame retardant is basically the same as that in Example 4, except that the boric acid in step A1 is replaced with an equimolar amount of methylboric acid; in step A1, the amount of 1,3-diamino-2-propanol is 0.203 mol; in step A2, the amount of diethyl 4-chlorobutylphosphonate is 0.405 mol; and in step A3, the amount of γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 0.405 mol.

[0041] Comparative Example 5 The raw material composition and preparation method of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material are basically the same as those in Example 6, except that the flame retardant is replaced with an equal weight of a flame retardant prepared by the following method: The preparation method of the flame retardant is basically the same as that in Example 4, except that 1,3-diamino-2-propanol in step A1 is replaced with an equimolar amount of 3-aminopropanol, the amount of 4-chlorobutylphosphonate diethyl ester in step A2 is 0.305 mol, and the amount of γ-(2,3-epoxypropoxy)propyltrimethoxysilane in step A3 is 0.305 mol.

[0042] Comparative Example 6 The raw material composition and preparation method of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material are basically the same as those in Example 6, except that the flame retardant is replaced with an equal weight of a flame retardant prepared by the following method: The preparation method of the flame retardant is basically the same as that in Example 4, except that the 4-chlorobutylphosphonate diethyl ester in step A2 is replaced with an equimolar amount of (diethyl)(chloromethyl) phosphate.

[0043] Comparative Example 7 The raw material composition and preparation method of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material are basically the same as those in Example 6, except that the flame retardant is replaced with an equal weight of a flame retardant prepared by the following method: The preparation method of the flame retardant is basically the same as that in Example 4, except that γ-(2,3-epoxypropoxy)propyltrimethoxysilane in step A3 is replaced with an equimolar amount of 5,6-epoxyhexyltriethoxysilane.

[0044] The polyethylene used in the embodiments and comparative examples of this application is of type 5000S, produced by Sinopec Yangzi Petrochemical Co., Ltd.; the maleic anhydride-grafted polyethylene is of type EPOLENE. C-26; the nano titanium dioxide model is LT-TiO2-004-2, produced by Shanghai Liantian Materials Technology Co., Ltd.; the straw powder is corn straw powder with a particle size of 50-80 mesh.

[0045] The limiting oxygen index, tensile strength, and antibacterial properties of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite materials prepared in the examples and comparative examples were tested, and the test results are shown in Table 1.

[0046] Sample preparation: The antibacterial, flame-retardant and environmentally friendly wood-plastic composite materials prepared in the examples and comparative examples were cut into samples required for testing using a universal sample preparation machine.

[0047] Limiting oxygen index test: According to GB / T 2406.2-2009, the limiting oxygen index was tested using a JF-3 oxygen index tester with method A - top surface ignition method. The sample shape was type II and the sample size was 120mm×10mm×10mm.

[0048] Tensile strength test: The tensile strength test shall be carried out in accordance with the provisions of GB / T1040.2-2006, using type 1A specimen; the tensile speed shall be 10 mm / min.

[0049] Antibacterial performance test: Circular samples with a diameter of 9 mm and a thickness of 2 mm were placed in capped glass bottles containing PBS buffer (0.1 M, pH=7.4). The samples were autoclaved at 121°C for 15 min, cooled under ventilation, and then further sterilized by UV irradiation in a clean bench for 1 h. The tested bacterial strain was Staphylococcus aureus. Individual colonies were picked from the test strain and diluted with physiological saline to a bacterial concentration of 10-1. 8 CFU / ml. Drop 100 μl of bacterial suspension onto LB solid medium, spread the suspension evenly with a spreader, attach the cut-out test sample, seal, and place the culture dish in a 37℃ biochemical incubator for constant temperature incubation. After 24 h, remove the dish to observe the bacterial growth on the medium and record the size of the inhibition zone.

[0050] Table 1 Performance Indicators of Antibacterial, Flame-Retardant, and Environmentally Friendly Wood-Plastic Composite Materials

[0051] As can be seen from Table 1, the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite materials prepared in Examples 5-7 of this application have excellent flame-retardant properties, tensile properties, and antibacterial properties.

[0052] The antibacterial agent prepared in this application connects guanidine groups, benzene rings, and triphenyl quaternary phosphonium salt groups via ester bonds and long-chain thioether bonds. The positive charge of the quaternary phosphonium salt group is adsorbed onto the negatively charged bacterial cell membrane surface through electrostatic interactions, disrupting the lipid bilayer structure of the cell membrane and causing leakage of intracellular contents. The guanidine group, as a protonating group and hydrogen bond donor, carries a high density of positive charge, which not only enhances the electrostatic adsorption and penetration of the bacterial membrane but also binds to the negatively charged centers (such as carboxyl and phosphate groups) of biomolecules such as proteins and enzymes on or inside the cell membrane, inhibiting their biological activity. The thioether group provides hydrophobic sulfur atom sites, which can enhance the interaction between the molecule and bacterial cell membrane proteins and lipids, improving the binding capacity and bactericidal efficiency of the antibacterial agent. In addition, the long alkyl chains, ester bonds, and thioether bonds in the antibacterial agent increase the flexibility of the molecular chain, improve the interfacial compatibility between straw powder and polyethylene, reduce stress concentration points, and improve the tensile properties of the material. Meanwhile, the quaternary phosphonium cation and guanidine group can form hydrogen bonds with the hydroxyl groups on the surface of straw powder, further enhancing the interfacial bonding strength between the filler and the matrix, thereby improving the tensile strength. The synergistic effect of the multifunctional groups of the antibacterial agent not only endows wood-plastic composites with excellent antibacterial properties but also effectively improves their mechanical properties, achieving a synergistic enhancement of both antibacterial and mechanical properties.

[0053] In Comparative Example 2, the carbon chain length of (3-propanoyl)triphenylphosphine bromide is shorter than that of the original 6-carboxyhexyltriphenylphosphine bromide. The shorter linker weakens the overall hydrophobicity and steric flexibility of the antibacterial molecule, resulting in a decrease in its ability to disrupt bacterial cell membranes. Simultaneously, the shorter carbon chain may also affect the dispersibility and interfacial compatibility of the antibacterial agent in the polymer matrix, thereby indirectly weakening its antibacterial efficiency.

[0054] The flame retardant prepared in this application has a multi-arm structure centered on a borate ester, containing phosphate ester groups and siloxane groups. The phosphonic acid groups, upon thermal decomposition, promote char formation on the material surface and release phosphorus-containing free radicals in the gas phase, capturing highly reactive free radicals in the combustion chain reaction and exerting a gas-phase flame-retardant effect. The central borate ester structure pyrolyzes to generate boron oxides and glassy borates, which synergistically form a more stable phosphorus-boron glass layer with phosphoric acid, further enhancing the thermal stability and oxygen barrier properties of the char layer and significantly improving the limiting oxygen index of the material. The siloxane groups hydrolyze and condense to form a Si-O-Si network, which migrates to the material surface to form a high-temperature resistant silicon-oxygen protective layer. This layer, synergistically with the phosphorus-boron glass layer, constructs multiple inorganic barriers, significantly inhibiting the release of molten droplets and toxic fumes, achieving efficient condensed phase and gas-phase dual flame retardancy. Regarding tensile properties, after hydrolysis, the siloxane groups undergo a condensation reaction with the hydroxyl groups on the surface of straw powder to form covalent Si-OC bonds, reducing phase separation and stress concentration, and improving the tensile strength of the material. The synergistic effect of multiple functional groups not only endows wood-plastic composites with excellent flame retardant properties, but also effectively balances mechanical properties, achieving a synergistic improvement in high flame retardancy and high strength.

[0055] In Comparative Example 4, after boric acid was replaced with methylboric acid, the reactive sites of the central boron atom were reduced from three hydroxyl groups to two. The branching degree and the number of functional groups of the resulting flame retardant molecule were reduced. Its gas-phase free radical capture ability, char formation catalytic efficiency and the number of connection points as an interfacial compatibilizer were significantly weakened, thereby reducing the flame retardant performance.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. An antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material, characterized in that, The ingredients include the following parts by weight: Polyethylene 40-60 parts, straw powder 30-40 parts, nano titanium dioxide 5-10 parts, lubricant 1-3 parts, compatibilizer 1-3 parts, antibacterial agent 0.8-1.8 parts, flame retardant 2-5 parts, foaming agent 1-2 parts; The antibacterial agent is prepared by the following method: S1: 11-Dodecenol reacts with 6-carboxyhexyltriphenylphosphonium bromide to generate intermediate 1. S2: Intermediate 1 reacts with 4-aminobenzylthiophenol to generate intermediate 2. S3: Intermediate 2 reacts with 1H-pyrazole-1-formamidinium hydrochloride to generate an antibacterial agent.

2. The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to claim 1, characterized in that, In step S1, the molar ratio of 11-dodecenol to 6-carboxyhexyltriphenylphosphonium bromide is 1:(1.02-1.05).

3. The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to claim 1, characterized in that, In step S2, the molar ratio of intermediate 1 to 4-aminothiophenol is (1.05-1.1):

1.

4. The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to claim 1, characterized in that, In step S3, the molar ratio of intermediate 2 to 1H-pyrazole-1-formamidinium hydrochloride is 1:(1.05-1.1).

5. The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to claim 1, characterized in that, The flame retardant is prepared by the following method: A1: Boric acid reacts with 1,3-diamino-2-propanol to form a hexaamino compound. A2: A hexaamino compound reacts with diethyl 4-chlorobutylphosphonate to form a hexaphosphate compound. A3: Hexaphosphate compounds react with γ-(2,3-epoxypropoxy)propyltrimethoxysilane to form flame retardants.

6. The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to claim 5, characterized in that, In step A1, the molar ratio of boric acid to 1,3-diamino-2-propanol is 1:3.

03.

7. The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to claim 5, characterized in that, In step A2, the molar ratio of the hexaamino compound to diethyl 4-chlorobutylphosphonate is 1:6.05; in step A3, the molar ratio of the hexaphosphate compound to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:6.

05.

8. The antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to claim 1, characterized in that, The lubricant is calcium stearate; the compatibilizer is maleic anhydride-grafted polyethylene; and the foaming agent is azodicarbonamide.

9. A method for preparing an antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 40-60 parts polyethylene, 30-40 parts straw powder, 5-10 parts nano titanium dioxide, 1-3 parts lubricant, 1-3 parts compatibilizer, 0.8-1.8 parts antibacterial agent, 2-5 parts flame retardant, and 1-2 parts foaming agent; (2) Polyethylene, straw powder, nano titanium dioxide, lubricant, compatibilizer, antibacterial agent, flame retardant and foaming agent are added to the mixing machine in sequence for melt mixing; then hot pressing and cold pressing are used to obtain antibacterial, flame retardant and environmentally friendly wood-plastic material.

10. The application of the antibacterial, flame-retardant, and environmentally friendly wood-plastic composite material according to any one of claims 1-8 on a cover plate.

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