Preparation method and application of boron-containing flame-retardant antibacterial polypropylene-based bamboo-plastic composite material

Abstract

The invention discloses a preparation method of a boron-containing flame-retardant antibacterial polypropylene-based bamboo-plastic composite material. According to the method, a modified aqueous solution containing a boron component is adopted, the bamboo powder is subjected to dipping treatment under the normal-temperature stirring condition, the boron element is successfully loaded on the surface and the interior of the bamboo powder, and the boron-containing bamboo powder with the flame-retardant and antibacterial functions is obtained. The mechanism is that the boron element can promote the composite material to form a compact and continuous protective carbon layer in the combustion process, heat and oxygen are effectively isolated, and therefore the efficient flame-retardant effect is achieved; meanwhile, the introduced boron element also has a remarkable antibacterial property. And then mixing the boron-containing bamboo powder with polypropylene resin and an intumescent flame retardant to obtain the bamboo-plastic composite material with excellent comprehensive performance. The method is simple in process and mild in condition, the flame-retardant and antibacterial properties of the composite material are remarkably improved, and high-value utilization of bamboo powder resources is achieved. The prepared composite material has wide application prospects in the fields of buildings, home furnishing, packaging and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer flame-retardant and antibacterial composite materials, specifically to a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material and its application. Background Technology

[0002] In the construction materials sector, bamboo is considered an ideal alternative to wood due to its rapid growth, renewable nature, large reserves, and high specific strength, helping to alleviate the domestic timber supply and demand imbalance. However, bamboo's natural properties of being prone to moisture absorption and mold growth result in insufficient durability in applications. On the other hand, while plastic materials, represented by polypropylene, excel in lightweighting, corrosion resistance, and processing economy, they are difficult to degrade in the natural environment after disposal, leading to a growing problem of "white pollution." Combining bamboo with plastics to prepare bamboo-plastic composites can achieve complementary advantages, thus inhibiting the biological degradation of bamboo while reducing the pure consumption of plastics. This material has significant industrial applicability and represents an important development direction for alleviating the dual pressures on resources and the environment.

[0003] Furthermore, the flame retardancy of bamboo-plastic composites is also a major challenge. Both bamboo powder and polypropylene are flammable materials, and their composite system has a fast flame propagation speed and a high fire safety hazard, which seriously limits its application in fields with high requirements for flame retardancy. Summary of the Invention

[0004] This invention addresses the shortcomings of existing bamboo-plastic composites in terms of flame retardancy and antibacterial properties by providing a simple and high-performance method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite. The core of the method lies in first functionalizing the bamboo powder. Specifically, at room temperature, the bamboo powder is placed in an aqueous solution containing boron and stirred for impregnation, effectively loading boron into the bamboo powder to obtain boron-containing bamboo powder with both flame-retardant and antibacterial functions. Subsequently, this boron-containing bamboo powder is melt-blended with polypropylene resin and an intumescent flame retardant, and then extruded to obtain the target composite material.

[0005] The present invention provides the following technical solution: On the one hand, the present invention provides a method for modifying bamboo powder with an aqueous solution containing boron.

[0006] Furthermore, the mass fraction of the boron-containing component in the solution is 10~30 wt%.

[0007] Furthermore, the bamboo powder has a mass fraction of 5-15 wt% in the boron-containing aqueous solution.

[0008] Furthermore, the boron-containing component is selected from one of borax, boric acid, disodium octaborate, and phenyldiboronic acid.

[0009] In another aspect, the present invention provides a method for modifying bamboo powder as described above, comprising the following steps: The boron-containing component is dissolved in water to obtain a boron-containing aqueous solution; The bamboo powder is soaked in the boron-containing aqueous solution to obtain modified bamboo powder.

[0010] Furthermore, the bamboo powder is soaked in a boron-containing aqueous solution for 30 minutes; The bamboo powder is soaked in a boron-containing aqueous solution at a temperature of 20-30 °C. The drying temperature is 60~80 °C; The drying time is 24-48 hours.

[0011] Furthermore, the preparation method includes the following steps: S1. Dissolve the boron-containing component in deionized water at room temperature using magnetic stirring (500 rpm) for 30 min.

[0012] S2. Subsequently, a predetermined amount of bamboo powder is added to an aqueous solution containing boron components. Under stirring conditions, the bamboo powder is fully dispersed and continuously impregnated. After treatment, the mixture is filtered to collect the bamboo powder solids, which are then subjected to washing and drying processes to finally obtain the surface-modified bamboo powder product.

[0013] In another aspect, the present invention provides a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material, comprising polypropylene and the modified bamboo powder as described in any one of claims 3 to 5.

[0014] Furthermore, the raw materials in the bamboo-plastic composite material include the following components: 100 parts by weight of a mixture of polypropylene and modified bamboo powder, and 14 to 26 parts by weight of flame retardant.

[0015] Furthermore, the mass ratio of the polypropylene to the modified bamboo powder is maintained at 1:1.

[0016] Furthermore, the polypropylene is isotactic polypropylene with a melt index of 2.6 g / 10 min.

[0017] Furthermore, the flame retardant is piperazine pyrophosphate with a purity of 99%.

[0018] Further, the polypropylene, modified bamboo powder, and piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture and then mixed evenly.

[0019] Furthermore, the material is extruded using a twin-screw extruder at 80-100 rpm and 170-190 °C, and then injection molded at 3-6 bar and 170-190 °C.

[0020] On the other hand, this invention also provides applications of the boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material prepared by the above method. Based on the excellent comprehensive flame-retardant and antibacterial properties of this composite material (achieving a UL-94 V-0 rating, demonstrating significant inhibitory effects against Staphylococcus aureus and mold), it is particularly suitable for fields with high requirements for material hygiene and fire safety, such as wall panels, floors, and skirting boards for building interior decoration; decorative components for public places; kitchen utensils, bathroom accessories, and children's furniture in household products; and special packaging materials for food, medical supplies, and other products.

[0021] The beneficial effects of this invention are as follows: The introduced boron element not only acts as a flame retardant, promoting the formation of a dense char layer during combustion, but also exhibits a synergistic effect with the phosphorus-based intumescent flame retardant in the system, significantly improving the limiting oxygen index of the composite material and reducing the heat release rate. Boron itself has an inhibitory effect on various bacteria and molds, fundamentally improving the inherent defects of natural bamboo powder, such as its susceptibility to mold and bacterial growth, and expanding the material's application potential in environments with high hygiene requirements. The bamboo powder modification process is carried out at room temperature, is simple, energy-efficient, and under mild conditions, making it easy to implement. Simultaneously, it achieves high-value utilization of bamboo powder resources, demonstrating good economic and environmental benefits. Attached Figure Description

[0022] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0023] Figure 1 The images are scanning electron microscope images of the surface of modified bamboo powder, showing the microstructure of the modified bamboo powder.

[0024] Figure 2 The images show the morphological characteristics of Example 3 and Comparative Example 1 after culturing in a medium containing Staphylococcus aureus for 24 h.

[0025] Figure 3 The images show the appearance of Example 3 and Comparative Example 1 after being placed in deionized water for 28 days. Detailed Implementation

[0026] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0027] The borax has a purity of 99% and was purchased from a Beijing chemical plant; the flame retardant is piperazine pyrophosphate with a purity of 99% and was purchased from Sichuan Jingshida Technology Co., Ltd.; unless otherwise specified, other reagents can also be purchased commercially.

[0028] Example 1 This embodiment provides a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material: S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0029] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0030] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 140 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed for 15 min using a high-speed mixer, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens using an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0031] Example 2 This embodiment provides a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material: S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0032] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0033] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 180 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed in a high-speed mixer for 15 min, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens in an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0034] Example 3 This embodiment provides a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material: S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0035] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0036] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 220 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed for 15 min using a high-speed mixer, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens using an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0037] The results of the antibacterial and antifungal performance tests on the two groups of samples are as follows: Figure 2 and Figure 3 As shown in the figure, the composite material prepared using unmodified bamboo powder did not form a clear inhibition zone on Staphylococcus aureus test plates, and obvious bacterial spots or mold appeared on the surface after soaking in deionized water for 28 days, indicating that it does not have significant antibacterial and antifungal capabilities. In contrast, the composite material prepared using borax-modified bamboo powder not only exhibited a clear inhibition zone under the same conditions, but also remained clean on the surface after long-term soaking, with no obvious mold growth, proving that the modified bamboo powder can effectively endow the composite material with the function of inhibiting the growth of bacteria and mold.

[0038] Example 4 This embodiment provides a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material: S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0039] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0040] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 260 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed in a high-speed mixer for 15 min, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens in an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0041] Comparative Example 1 This comparative example provides a method for preparing a polypropylene-based bamboo-plastic composite material: S1. 500 g of polypropylene, 500 g of unmodified bamboo powder, and 220 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed in a high-speed mixer for 15 min, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens using an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0042] Comparative Example 2 This comparative example provides a method for preparing a polypropylene-based bamboo-plastic composite material to investigate the effect of excessive flame retardant on performance: This embodiment provides a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material: S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0043] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0044] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 270 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed in a high-speed mixer for 15 min, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens in an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0045] Comparative Example 3 This comparative example provides a method for preparing a polypropylene-based bamboo-plastic composite material to investigate the effect of insufficient flame retardant on performance: This embodiment provides a method for preparing a boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material: S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0046] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0047] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 130 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed in a high-speed mixer for 15 min, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens in an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0048] Comparative Example 4 This comparative example provides a method for preparing a polypropylene-based bamboo-plastic composite material to investigate the effect of the type of flame retardant on the properties of the composite material. S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0049] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0050] S3. 500 g of polypropylene, 500 g of the modified bamboo powder described above, and 220 g of ammonium polyphosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, the mixture was blended for 15 min using a high-speed mixer, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens using an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0051] Comparative Example 5 This comparative example provides a method for preparing a polypropylene-based bamboo-plastic composite material to investigate the effect of insufficient bamboo powder impregnation time on the composite material properties: S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 30 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0052] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 10 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0053] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 220 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed for 15 min using a high-speed mixer, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens using an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0054] Comparative Example 6 This comparative example provides a method for preparing a polypropylene-based bamboo-plastic composite material to investigate the effect of excessively long bamboo powder impregnation time on the properties of the composite material. S1. Weigh 400 g of borax and dissolve it in 2000 mL of deionized water. Stir the mixture magnetically (500 rpm) at room temperature for 50 min to obtain a boron-containing aqueous solution with a mass fraction of approximately 20 wt%.

[0055] S2. Subsequently, 200 g of 100-mesh bamboo powder was added to the above solution, and the bamboo powder was fully dispersed and continuously impregnated under the same stirring conditions for 30 min. After the treatment was completed, the mixture was filtered to collect the bamboo powder solid, and then washed three times with deionized water and dried in a vacuum oven at 80 °C for 24 h to finally obtain the surface-modified bamboo powder product.

[0056] S3. 500 g of polypropylene, 500 g of the above-mentioned modified bamboo powder, and 220 g of piperazine pyrophosphate were vacuum dried at 80 °C for 12 h to remove moisture. Then, they were mixed for 15 min using a high-speed mixer, followed by melt blending and extrusion granulation using a twin-screw extruder (screw speed 80 rpm, barrel temperature 180 °C). Finally, the masterbatch was injection molded into standard test specimens using an injection molding machine (injection pressure 5 bar, injection temperature 180 °C).

[0057] The conventional combustion performance and antibacterial performance of polypropylene-based bamboo-plastic composites were tested according to the following standards, and the results are shown in Table 1.

[0058] Impact strength of cantilever beam: Tested according to GB / T1043.1-2018 standard, the impact energy is 2 J; Tensile strength: Tested according to GB / T1040.1-2018 standard, at a test speed of 5 mm / min; Flammability performance: LOI standard test according to GB / T2406-2015, UL test according to GB / T2408-2008. 94 standard test.

[0059] Figure 1 The images are scanning electron microscope (SEM) images of the modified bamboo powder, showing the microstructure of the modified bamboo powder.

[0060] Figure 2 The images show the morphological characteristics of Example 3 and Comparative Example 1 after culturing in a medium containing Staphylococcus aureus for 24 h.

[0061] Figure 3 The images show the appearance of Example 3 and Comparative Example 1 after being placed in deionized water for 28 days.

[0062] Table 1 Conclusion: The boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material of the present invention exhibits excellent comprehensive performance. As shown in Table 1, all embodiments achieved UL-94 V-0 flame retardancy rating, with limiting oxygen index (LOI) above 20.3%. In terms of mechanical properties, the embodiments of the present invention achieve a good balance between excellent flame retardancy and mechanical properties. In contrast, Comparative Example 2 showed significant deterioration in mechanical properties due to excessive addition of flame retardant; Comparative Example 3, due to insufficient addition of flame retardant, only achieved a V-2 flame retardancy rating, failing to meet the requirements. These two comparative examples, from the opposite perspective, confirm the necessity of the flame retardant dosage range determined in the present invention. Furthermore, after changing the type of flame retardant, all properties of Comparative Example 4 declined, further confirming the irreplaceable synergistic effect of piperazine pyrophosphate in this modified system. Further changing the impregnation modification time of bamboo powder, Comparative Example 5 failed to pass the V-0 rating due to insufficient impregnation time, while Comparative Example 6 showed a significant decline in mechanical properties after excessive impregnation time. In summary, this invention effectively overcomes the technical bottleneck of the difficulty in synergistically improving flame retardancy and mechanical properties in bamboo-plastic composite materials.

[0063] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A boron-containing flame-retardant and antibacterial polypropylene-based bamboo-plastic composite material, characterized in that, The polypropylene-based bamboo-plastic composite material includes polypropylene, modified bamboo powder, and flame retardant; The modified bamboo powder is obtained by impregnation treatment with an aqueous solution containing boron components; The boron-containing component is selected from at least one of borax, boric acid, disodium octaborate, and phenyldiboronic acid.

2. The polypropylene-based bamboo-plastic composite material according to claim 1, characterized in that, The polypropylene-based composite material comprises the following components in parts by weight: 100 parts by weight of a mixture of polypropylene and modified bamboo powder; wherein the mass ratio of polypropylene to modified bamboo powder is 1:1; Flame retardant piperazine pyrophosphate 14-26 parts; The modified bamboo powder has a mesh size of 50-100 mesh.

3. A method for preparing the polypropylene-based bamboo-plastic composite material according to claim 1, characterized in that, The preparation method includes the following steps: (I) Preparation of modified bamboo powder: A predetermined amount of bamboo powder was added to an aqueous solution containing boron components. The bamboo powder was fully dispersed and continuously impregnated under stirring conditions. After the treatment was completed, the mixture was filtered to collect the bamboo powder solids, which were then washed and dried to finally obtain the surface-modified bamboo powder product. (II) Molding of the composite material: Weigh polypropylene, the obtained modified bamboo powder, and the flame retardant according to the specified proportions, and put them into a mixing device for thorough mixing. Transfer the mixture to a twin-screw extruder for melt blending and extrusion granulation to obtain bamboo-plastic composite material masterbatch. Subsequently, process the masterbatch through injection molding to obtain the target polypropylene-based bamboo-plastic composite material.

4. The preparation method according to claim 3, characterized in that, In step (I), the boron-containing solution has a mass fraction of 10-30 wt%. The ratio of the bamboo powder to the aqueous solution of the boron-containing component is 5~15 g : 100 mL; The bamboo powder was soaked in a boron-containing aqueous solution for 30 minutes. The bamboo powder is soaked in a boron-containing aqueous solution at a temperature of 20-30 °C. The drying temperature is 60~80 °C; The drying time is 24-48 hours.

5. The preparation method according to claim 3, characterized in that, The screw speed of the twin-screw extruder is 80~100 rpm; The barrel temperature of the twin-screw extruder is 170~190 °C; The injection molding temperature is 170~190 °C; The injection molding pressure is 3~6 bar.

6. An article, characterized in that, The article is made of polypropylene-based bamboo-plastic composite material prepared by any one of claims 1 to 5.

7. The article of claim 6, characterized in that, The products mentioned are building materials, home furnishings, and packaging.

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