Bamboo fiber reinforced polypropylene alloy material as well as preparation method and application thereof

Abstract

The invention discloses a bamboo fiber reinforced polypropylene alloy material as well as a preparation method and application thereof. Relates to the technical field of high polymer materials and comprises the following components in parts by weight: 35-85 parts of polypropylene resin, 10-40 parts of natural bamboo fibers, 3-5 parts of a flame retardant, 3-5 parts of a coupling agent, 0.1-0.5 part of an antioxidant, 0.1-0.5 part of a light stabilizer, 3-5 parts of a compatilizer and 0.1-1 part of a processing aid. Polypropylene grafted maleic anhydride is adopted as a compatilizer between bamboo fibers and polypropylene, the maleic anhydride end can chemically react with rich hydroxyl groups on the surfaces of the bamboo fibers to form chemical bond connection, and the polypropylene end can be fused with a polypropylene matrix to form a composite material. Therefore, the interface bonding force between the bamboo fibers and the polypropylene matrix is effectively improved, the bamboo fibers can be uniformly dispersed in the polypropylene matrix as far as possible, and the comprehensive mechanical properties, such as tensile strength, bending strength and impact strength, of the composite material are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a bamboo fiber reinforced polypropylene alloy material, its preparation method, and its application. Background Technology

[0002] Reinforced polypropylene is widely used in interior decoration materials due to its high strength and low density. Traditional reinforced polypropylene mainly uses glass fiber. As people's focus on environmentally friendly products continues to rise, the market demand for biodegradable and low-energy materials is increasing. Bamboo fiber, as a representative of green materials, aligns with market demand trends, bringing greater market competitiveness and commercial value to enterprises and driving the industry towards green and sustainable development.

[0003] Bamboo fiber, derived from natural bamboo, is lightweight, strong, abundant, and inexpensive. Extracted through a special process, its unique cellular structure endows the material with excellent flexibility and biodegradability. While glass fiber boasts high strength, it is non-biodegradable and requires significant energy to process. Bamboo fiber, with its environmentally friendly, recyclable, and superior mechanical properties, holds the promise of revolutionizing traditional material applications at the technological level, injecting new vitality into the industry. In industries such as automotive interiors and building materials, bamboo fiber can open up entirely new application avenues thanks to its natural antibacterial, sound-absorbing, and heat-insulating properties. Bamboo fiber fabrics not only improve in-vehicle air quality but also meet consumer demand for environmentally friendly materials. In contrast, glass fiber's application in these areas is limited; the introduction of bamboo fiber can effectively expand the boundaries of industrial applications. Simultaneously, introducing natural bamboo fiber as a reinforcing agent into polypropylene materials to prepare bamboo fiber-reinforced polypropylene composites is expected to significantly improve the material's mechanical properties, such as strength and modulus, while reducing material costs. Furthermore, it can bring substantial social benefits, aligning with the development trend of "green, environmentally friendly, low-carbon, and renewable," making it a highly promising new material.

[0004] However, a key technical challenge in preparing bamboo fiber reinforced polypropylene composites is the compatibility between bamboo fibers and the polypropylene matrix. Natural bamboo fibers contain numerous polar hydroxyl groups on their surface, exhibiting hydrophilicity, while polypropylene is a typical hydrophobic polymer lacking hydrophilic groups. This difference in polarity results in very weak interfacial bonding between the two. During composite material preparation, bamboo fibers are prone to agglomeration, making it difficult to disperse uniformly within the polypropylene matrix. This severely impacts the overall mechanical properties of the composite material, failing to meet the demands of practical applications. Therefore, improving the compatibility between bamboo fibers and the polypropylene matrix has become a crucial core technology for preparing high-performance bamboo fiber reinforced polypropylene composites.

[0005] Furthermore, in some applications, such as the electrical appliance industry, the flame retardancy of materials is also a crucial performance indicator. Traditional flame-retardant modification methods for polypropylene typically involve filling with flame retardants, often using halogenated organic compounds such as dodecyl bromide or octabromodiphenyl ethane. However, in the UL94 V0 flame retardancy rating test, halogenated flame retardants like dodecyl bromide often fail to meet the standard's requirement of not igniting absorbent cotton. To barely meet the flame retardancy standard, a significant increase in the amount of flame retardant is often required. However, excessive addition of fillers negatively impacts the material's mechanical properties, leading to a decrease in strength, toughness, and other properties, making it impossible to achieve a balance between flame retardancy and mechanical properties.

[0006] In conclusion, developing a bamboo fiber reinforced polypropylene alloy material and its preparation method that can effectively improve the compatibility between bamboo fiber and polypropylene matrix while taking into account the material's mechanical properties and flame retardant properties is of great practical significance and market demand. Summary of the Invention

[0007] This invention addresses the problem of poor mechanical and flame-retardant properties in existing bamboo fiber reinforced polypropylene alloy materials due to the poor compatibility between bamboo fiber and the polypropylene matrix.

[0008] To address the aforementioned problems, this invention discloses a bamboo fiber reinforced polypropylene alloy material, comprising the following components in parts by weight: 35-85 parts polypropylene resin, 10-40 parts natural bamboo fiber, 3-5 parts flame retardant, 3-5 parts coupling agent, 0.1-0.5 parts antioxidant, 0.1-0.5 parts light stabilizer, 3-5 parts compatibilizer, and 0.1-1 parts processing aid; The compatibilizer is polypropylene grafted with maleic anhydride (PP-g-MAH).

[0009] The bamboo fiber reinforced polypropylene alloy material provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: The bamboo fiber reinforced polypropylene alloy material of the present invention comprises, by weight, 35-85 parts of polypropylene resin, 10-40 parts of natural bamboo fiber, 3-5 parts of flame retardant, 3-5 parts of coupling agent, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of light stabilizer, 3-5 parts of compatibilizer, and 0.1-1 parts of processing aid. This raw material ratio optimizes the synergistic effect between the components. Furthermore, the use of polypropylene grafted with maleic anhydride as a compatibilizer between bamboo fiber and polypropylene allows the maleic anhydride end to undergo esterification with the abundant hydroxyl groups on the bamboo fiber surface, forming chemical bonds. Simultaneously, the polypropylene end can fuse with the polypropylene matrix, effectively improving the interfacial bonding force between the bamboo fiber and the polypropylene matrix. This enables the bamboo fiber to be dispersed as uniformly as possible within the polypropylene matrix, thereby significantly improving the comprehensive mechanical properties of the composite material, such as tensile strength, flexural strength, and impact strength.

[0010] Furthermore, the polypropylene resin is any one of isotactic polypropylene, syndiotactic polypropylene, and atactic polypropylene; the melt flow index of the polypropylene resin at 220℃ and 2.20kg is 10-60g / min.

[0011] Specifically, isotactic polypropylene has high crystallinity, providing excellent rigidity and strength; syndiotactic polypropylene may offer better transparency and toughness; and atactic polypropylene improves flexibility and processability. A melt flow index within the range of 10-60 g / min ensures that the polypropylene resin has appropriate flowability and molecular weight, facilitating uniform mixing with bamboo fiber and other additives during processing. This avoids bamboo fiber settling due to excessively high flowability or processing difficulties due to excessively low flowability. This contributes to the formation of a uniform composite material structure, further enhancing mechanical properties and ensuring the stability of the material during extrusion or injection molding.

[0012] Furthermore, the average length of the natural bamboo fiber is 5-50mm, and it is obtained from 1-3 year old new bamboo; the cellulose content of the natural bamboo fiber is more than 60%; the far-infrared emissivity is ≥0.87; the moisture regain is >45% under the conditions of temperature of 36℃ and relative humidity of 100%, and the air permeability is 4.5 times that of cotton.

[0013] Specifically, bamboo fiber lengths within the 5-50mm range effectively reinforce the polypropylene matrix; too short a length results in insufficient reinforcement, while too long a length makes dispersion difficult. New bamboo fibers aged 1-3 years exhibit higher strength and flexibility. A high cellulose content (≥60%) signifies high fiber purity and strong reactivity, facilitating chemical bonding with the maleic anhydride end of the compatibilizer PP-g-MAH, thereby strengthening interfacial adhesion. High far-infrared emissivity (≥0.87) endows the material with health benefits, such as promoting blood circulation and providing warmth. High moisture regain (>45%) and breathability (4.5 times that of cotton) give the material excellent moisture-wicking properties, enhancing comfort and making it suitable for applications requiring breathability and moisture resistance. These characteristics collectively improve the material's overall performance, particularly in home appliances and automotive interiors, enhancing the user experience.

[0014] Furthermore, the flame retardant is phospho-esterified β-cyclodextrin, which is obtained by interfacial condensation reaction of benzylphosphonodichloro and β-cyclodextrin.

[0015] Specifically, the porous structure of β-cyclodextrin can adsorb combustion gases, while phosphorus promotes char formation during combustion, isolating oxygen and heat, thereby improving flame retardant properties. Interfacial condensation reaction ensures the uniformity and stability of phospho-esterified β-cyclodextrin, allowing it to disperse well in the polypropylene matrix and synergistically with bamboo fiber and the compatibilizer PP-g-MAH without compromising mechanical properties. Simultaneously, this flame retardant reduces the release of toxic fumes, meeting the safety standards for household appliances and automotive products.

[0016] Furthermore, the coupling agent is any one of silane coupling agents, titanate coupling agents, aluminate coupling agents, and phosphate coupling agents.

[0017] Specifically, silane coupling agents can form siloxane bonds with the hydroxyl groups on the surface of bamboo fibers, improving bond strength; titanate and aluminate coupling agents improve fiber dispersibility and processing flowability; and phosphate coupling agents also have flame-retardant effects. In synergy with the compatibilizer PP-g-MAH, the coupling agents enhance overall interfacial compatibility, reduce interfacial defects, and thus improve the mechanical properties and durability of the composite material.

[0018] Furthermore, the antioxidant is a hindered phenolic antioxidant.

[0019] Specifically, hindered phenolic antioxidants effectively capture free radicals generated in polypropylene during processing or use, preventing oxidative degradation and maintaining the material's molecular structure and performance stability. Especially under high-temperature processing conditions, hindered phenolic antioxidants delay material aging, prevent degradation of mechanical properties and color changes, extend material lifespan, and ensure the reliability of home appliances and automotive products during long-term use.

[0020] Furthermore, the light stabilizer is an ultraviolet absorber, a hindered amine light stabilizer, a quencher, or a light shielding agent.

[0021] Specifically, UV absorbers (such as benzotriazoles) can absorb UV light and convert it into heat energy; hindered amine light stabilizers can quench excited-state molecules; quenchers can transfer energy; and light shielding agents (such as carbon black) can reflect or scatter UV light. Thus, they can effectively prevent material embrittlement, discoloration, and surface degradation, maintain mechanical properties and appearance, and are suitable for household appliances and automotive parts in outdoor or light-exposed environments.

[0022] Furthermore, the processing aid is calcium stearate or polyethylene wax.

[0023] Specifically, calcium stearate also has lubricating and stabilizing effects, while polyethylene wax improves surface smoothness. This facilitates the smooth operation of extrusion and molding processes, improves production efficiency, and reduces product defects such as bubbles or pinholes, thereby ensuring the consistency and quality of the composite material.

[0024] The present invention also provides a preparation method for preparing the bamboo fiber reinforced polypropylene alloy material as described above, characterized by comprising the following steps: mixing polypropylene, flame retardant, coupling agent, antioxidant, light stabilizer, compatibilizer, and processing aid in proportion by weight and feeding them into an extruder through the main feed port; feeding pretreated natural bamboo fiber into the extruder through the side feed port; and then melting, extruding, granulating, cooling, and drying to obtain the bamboo fiber modified polypropylene composite material. The natural bamboo fiber is processed as follows: the natural bamboo fiber is heat-treated at 80℃ for 24 hours, then washed and dried with pure water; the dried bamboo fiber is treated in warm water at 50℃ for 2 hours, then boiled for 1 hour; the bamboo fiber is then soaked in a 5% sodium hydroxide solution and treated at 70℃ for 3 hours; after treatment, it is repeatedly rinsed with pure water until neutral, and then dried at 90℃ for later use.

[0025] The preparation method provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: During the preparation process, bamboo fiber is added through a side feed port to prevent premature exposure to high temperatures and degradation, thus maintaining its integrity. The melt extrusion process allows the compatibilizer PP-g-MAH to fully react with the bamboo fiber and polypropylene, forming chemical bonds and enhancing interfacial bonding. After granulation, cooling, and drying, uniform composite material particles are obtained, which facilitates subsequent processing (such as injection molding). This method ensures optimized dispersion and reaction of each component, maximizing the improvement of mechanical properties. More importantly, during the pretreatment of natural bamboo fiber, heat treatment can remove adsorbed moisture and some low-molecular-weight volatile substances from the fiber. Subsequently, hot water treatment (50℃ warm water + boiling) can dissolve and remove some water-soluble impurities, sugars, pectin, and oligomers. Sodium hydroxide solution can effectively hydrolyze and dissolve hemicellulose, lignin, and some pectin and waxes in bamboo fiber. After removing these substances, more of the crystalline structure of cellulose is exposed, and the activity of its abundant hydroxyl functional groups on the surface is improved, providing more reaction sites for the subsequent esterification reaction with the maleic anhydride ring of PP-g-MAH, so that the chemical bonding reaction can proceed more fully and firmly.

[0026] Moreover, sodium hydroxide solution can not only dissolve non-cellulose components, but also cause swelling and etching of amorphous regions of cellulose. This makes the fiber surface rough and may even produce tiny pores, providing a larger contact area and a more complex mechanical interlocking structure for the polymer matrix. When molten polypropylene resin impregnates the fiber, it can be better anchored to the fiber surface, improving the bonding strength.

[0027] Furthermore, the temperatures of each zone of the extruder are as follows: Zone 1 160℃, Zone 2 180℃, Zone 3 190℃, Zone 4 190℃, Zone 5 200℃, Zone 6 210℃, and Die head 200℃; the screw speed of the extruder is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is -0.06 MPa.

[0028] Specifically, the temperature gradient gradually increases from 160℃ to 210℃ to ensure slow melting of the material and avoid damage to the bamboo fiber from thermal shock. At the same time, the high-temperature zone (200-210℃) promotes the chemical reaction between the compatibilizer PP-g-MAH and the bamboo fiber. The screw speed of 500r / min provides moderate shear force, so that the bamboo fiber is evenly dispersed without breaking. The melt pressure of 1.0 MPa and the vacuum degree of -0.06MPa ensure stable extrusion, remove volatiles and bubbles, and improve the density and quality of the material.

[0029] The present invention also provides an application of the bamboo fiber reinforced polypropylene alloy material as described above, for use in home appliances and automotive products.

[0030] The application of the bamboo fiber reinforced polypropylene alloy material provided by this invention has, but is not limited to, the following beneficial effects compared to existing technologies: Based on the beneficial effects of the bamboo fiber reinforced polypropylene alloy material mentioned above, it can be seen that the material has high strength, high toughness, flame retardancy, weather resistance, breathability and environmental friendliness, making it very suitable for the needs of the home appliance and automotive industries; the addition of bamboo fiber reduces weight, achieving lightweighting, and gives it a natural aesthetic and comfortable feel; the excellent interfacial bonding ensured by the compatibilizer PP-g-MAH enables the material to remain stable under complex working conditions and extend product life. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0032] The terminology used in the embodiments of this application is for the purpose of describing particular implementations only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the implementations of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0033] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation rules of this application.

[0034] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0035] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application are available on the market or can be prepared by existing methods.

[0037] For example, some of the raw materials in the following embodiments are as follows.

[0038] Polypropylene resin: Isotactic polypropylene, with a melt index of 50 g / min at 220℃ and 2.20 kg. Natural bamboo fiber: with an average length of 30mm, it is made from one-year-old new bamboo and has a cellulose content of over 60%; far-infrared emissivity is 0.87; moisture regain is >45% under conditions of 36℃ and 100% relative humidity, and its breathability is 4.5 times that of cotton. Phosphoesterified β-cyclodextrin: C104384, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Silane coupling agent: KH550, purchased from Yingyu Chemical; Hindered phenolic antioxidants: Antioxidant 1076, purchased from BASF; Light stabilizer: 3808, purchased from Cytec; PP-g-MAH: Polypropylene grafted with maleic anhydride, purchased from BASF; Processing aid: Polyethylene wax, purchased from BASF; Black masterbatch: Purchased from Dongguan Jinsuyan Plastic Technology Co., Ltd.

[0039] Example 1

[0040] This embodiment discloses a bamboo fiber reinforced polypropylene alloy material, which is carried out in the following steps: Step 1: Prepare the following components by weight: 50 parts polypropylene resin, 25 parts natural bamboo fiber, 4 parts phosphoesterified β-cyclodextrin, 4 parts silane coupling agent, 0.3 parts hindered phenolic antioxidant, 0.3 parts light stabilizer, 4 parts PP-g-MAH, 0.3 parts processing aid, and 0.8 parts black masterbatch. Then, pretreat the natural bamboo fiber as follows: soak the natural bamboo fiber in 80℃ hot water for 24 hours, then wash and dry it with pure water; treat the dried bamboo fiber in 50℃ warm water for 2 hours, then boil it for 1 hour; next, soak the bamboo fiber in a 5% sodium hydroxide solution at 70℃ for 3 hours; after treatment, rinse repeatedly with pure water until neutral, and dry at 90℃ for later use.

[0041] Step 2: The polypropylene resin, flame retardant, coupling agent, antioxidant, light stabilizer, PP-g-MAH, and processing aids from Step 1 are mixed evenly in a high-speed mixer. Then, the mixture is fed into a screw extruder through the main feed port for melting, mixing, and dispersion. Next, the pretreated natural bamboo fiber is fed into a twin-screw extruder through the side feed port and plasticized at 200°C. Finally, the mixture is granulated by twin-screw extrusion. The temperatures of each zone of the twin-screw extruder are: Zone 1 160°C, Zone 2 180°C, Zone 3 190°C, Zone 4 190°C, Zone 5 200°C, Zone 6 210°C, and the die head 200°C. The screw speed of the extruder is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is -0.06 MPa. The final product is a bamboo fiber modified polypropylene alloy material.

[0042] Example 2

[0043] Compared with Example 1, the only difference is that in step one, the weight parts of the raw materials are adjusted to: 35 parts of polypropylene resin, 10 parts of natural bamboo fiber, 3 parts of phosphoesterified β-cyclodextrin, 3 parts of silane coupling agent, 0.1 parts of hindered phenolic antioxidant, 0.1 parts of light stabilizer, 3 parts of PP-g-MAH, 0.1 parts of processing aid, and 0.8 parts of black masterbatch; other steps and conditions remain the same, and bamboo fiber modified polypropylene alloy material is finally obtained.

[0044] Example 3

[0045] Compared with Example 1, the only difference is that in step one, the weight parts of the raw materials are adjusted to: 85 parts of polypropylene resin, 40 parts of natural bamboo fiber, 5 parts of phosphoesterified β-cyclodextrin, 5 parts of silane coupling agent, 0.5 parts of hindered phenolic antioxidant, 0.5 parts of light stabilizer, 5 parts of PP-g-MAH, 0.5 parts of processing aid, and 0.8 parts of black masterbatch; other steps and conditions remain the same, and bamboo fiber modified polypropylene alloy material is finally obtained.

[0046] Example 4

[0047] Compared with Example 1, the only difference is that in step one, the weight parts of the raw materials are adjusted to: 40 parts of polypropylene resin, 15 parts of natural bamboo fiber, 3.5 parts of phosphoesterified β-cyclodextrin, 3.5 parts of silane coupling agent, 0.2 parts of hindered phenolic antioxidant, 0.2 parts of light stabilizer, 3.5 parts of PP-g-MAH, 0.2 parts of processing aid, and 0.8 parts of black masterbatch; other steps and conditions remain the same, and bamboo fiber modified polypropylene alloy material is finally obtained.

[0048] Example 5

[0049] Compared with Example 1, the only difference is that in step one, the weight parts of the raw materials are adjusted to: 70 parts of polypropylene resin, 35 parts of natural bamboo fiber, 4.5 parts of phosphoesterified β-cyclodextrin, 4.5 parts of silane coupling agent, 0.4 parts of hindered phenolic antioxidant, 0.4 parts of light stabilizer, 4.5 parts of PP-g-MAH, 0.4 parts of processing aid, and 0.8 parts of black masterbatch; other steps and conditions remain the same, and bamboo fiber modified polypropylene alloy material is finally obtained.

[0050] Comparative Example 1

[0051] Compared with Example 1, the only difference is that PP-g-MAH is replaced with maleic anhydride, while the other steps and conditions remain the same, and bamboo fiber modified polypropylene alloy material is finally obtained.

[0052] Comparative Example 2

[0053] Compared with Example 1, the only difference is that the natural bamboo fiber is not pretreated, while the other steps and conditions remain the same, and bamboo fiber modified polypropylene alloy material is finally obtained.

[0054] The performance of the bamboo fiber modified polypropylene alloy materials obtained in Examples 1-4 was tested using the following methods: Density: Refer to GB / T 1033; Ash content: Refer to GB / T 9345.1; Melt flow index: Refer to GB / T 3682; Tensile strength: Refer to GB / T 1040; Elongation at break: Refer to GB / T 1040; Bending strength: Refer to GB / T 9341; Flexural modulus: Refer to GB / T 9341; Impact test of cantilever beam notched beam: Refer to GB / T 1843.

[0055] The test results are listed in Table 1, as follows: Table 1

[0056] Analysis of the data in Table 1 shows that, compared with Comparative Examples 1-2, the bamboo fiber modified polypropylene alloy materials prepared in Examples 1-5 have superior comprehensive mechanical properties, specifically in terms of tensile strength, elongation at break, flexural strength, flexural modulus, and cantilever beam notched impact performance.

[0057] The foregoing has described several embodiments of the present invention in detail, but these descriptions are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A bamboo fiber reinforced polypropylene alloy material, characterized in that, It includes the following components in parts by weight: 35-85 parts polypropylene resin, 10-40 parts natural bamboo fiber, 3-5 parts flame retardant, 3-5 parts coupling agent, 0.1-0.5 parts antioxidant, 0.1-0.5 parts light stabilizer, 3-5 parts compatibilizer, and 0.1-1 parts processing aid. The compatibilizer is polypropylene grafted with maleic anhydride.

2. The bamboo fiber reinforced polypropylene alloy material according to claim 1, characterized in that, The polypropylene resin is any one of isotactic polypropylene, syndiotactic polypropylene, and atactic polypropylene; the melt flow index of the polypropylene resin at 220℃ and 2.20kg is 10-60g / min.

3. The bamboo fiber reinforced polypropylene alloy material according to claim 1, characterized in that, The natural bamboo fiber has an average length of 5-50mm and is produced from 1-3 year old new bamboo; the cellulose content of the natural bamboo fiber is more than 60%; the far-infrared emissivity is ≥0.87; the moisture regain is >45% under the conditions of temperature of 36℃ and relative humidity of 100%, and the air permeability is 4.5 times that of cotton.

4. The bamboo fiber reinforced polypropylene alloy material according to claim 1, characterized in that, The flame retardant is phospho-esterified β-cyclodextrin, which is obtained by interfacial condensation reaction of benzylphosphonodichloro and β-cyclodextrin.

5. The bamboo fiber reinforced polypropylene alloy material according to claim 1, characterized in that, The coupling agent is any one of silane coupling agents, titanate coupling agents, aluminate coupling agents, and phosphate coupling agents.

6. The bamboo fiber reinforced polypropylene alloy material according to claim 1, characterized in that, The light stabilizer is an ultraviolet absorber, a hindered amine light stabilizer, a quencher, or a light shielding agent.

7. The bamboo fiber reinforced polypropylene alloy material according to claim 1, characterized in that, The processing aid is calcium stearate or polyethylene wax.

8. A preparation method for preparing the bamboo fiber reinforced polypropylene alloy material as described in any one of claims 1-7, characterized in that, The process includes the following steps: Polypropylene, flame retardant, coupling agent, antioxidant, light stabilizer, compatibilizer, and processing aid are mixed in proportion by weight and fed into the extruder through the main feed port. Pretreated natural bamboo fiber is fed into the extruder through the side feed port. After melting, extrusion, granulation, cooling, and drying, bamboo fiber modified polypropylene composite material is obtained. The natural bamboo fiber is processed as follows: the natural bamboo fiber is heat-treated at 80℃ for 24 hours, then washed and dried with pure water; the dried bamboo fiber is treated in warm water at 50℃ for 2 hours, then boiled for 1 hour; the bamboo fiber is then soaked in a 5% sodium hydroxide solution and treated at 70℃ for 3 hours; after treatment, it is repeatedly rinsed with pure water until neutral, and then dried at 90℃ for later use.

9. The preparation method according to claim 8, characterized in that, The temperatures of each zone of the extruder are as follows: Zone 1 160℃, Zone 2 180℃, Zone 3 190℃, Zone 4 190℃, Zone 5 200℃, Zone 6 210℃, and Die head 200℃; the screw speed of the extruder is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is -0.06 MPa.

10. An application of the bamboo fiber reinforced polypropylene alloy material as described in claim 1, characterized in that, Used in home appliances and automobiles.

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