A natural ecological biodegradable product and preparation method thereof

Abstract

The present invention relates to the field of biodegradable technology, and more particularly to a kind of natural ecological biodegradable product and preparation method thereof. The raw material of the above-mentioned natural ecological biodegradable product includes by mass: 50 60 parts of starch, 10 20 parts of cellulose fibers, 10 20 parts of polylactic acid, 1 5 parts of phytic acid, 1 2 parts of nano zinc oxide, 1 5 parts of mesoporous silica, 5 10 parts of plasticizers, 3 8 parts of compatibilizers, and 3 5 parts of nucleators. The present invention uses mesoporous silica loaded Zn phytic acid complexes, realizes nanoscale dispersion, avoids agglomeration during processing, and hinders crack propagation by pinning effect, and its surface active groups and starch are combined by hydrogen bond network and physical anchoring to strengthen interface, and the mechanical property of collaboratively improving product is improved, and under the premise of ensuring biodegradability, product mechanical tensile strength is effectively improved, and it is ensured that the comprehensive performance of product.

Description

Technical Field

[0001] The present invention relates to the field of biodegradation technology, in particular to a natural ecological biodegradable product and a preparation method thereof. Background Art

[0002] Biodegradable materials based on renewable resources are seen as a key breakthrough in solving the problem of plastic pollution. Among them, starch-based materials have become one of the most promising alternatives for industrialization due to their wide sources, low costs and excellent biocompatibility.

[0003] Starch is a natural high-molecular polysaccharide with rich hydroxyl groups on its molecular chain. In theory, it can be modified by plasticization to form a three-dimensional network structure. However, existing starch-based degradable materials have exposed significant technical bottlenecks in actual application: in terms of mechanical properties, the tensile strength of pure starch materials is generally low, which makes it difficult to meet the mechanical strength requirements of packaging materials; in terms of heat resistance, conventional starch-based products are prone to softening and deformation under high temperature conditions, which seriously restricts their application in packaging and other fields. What is more serious is that there is often a negative correlation between the mechanical properties and heat resistance of materials. Although the use of conventional plasticizers can improve processing fluidity, it will cause the glass transition temperature to drop significantly, forming a "strength-heat resistance" trade-off problem.

[0004] Currently, although mechanical properties can be improved by adding synthetic polymers such as polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) through blending modification, excessive addition will destroy the material's complete biodegradability. In nano-composite reinforcement technology, the dispersion uniformity of fillers such as montmorillonite and cellulose nanocrystals is difficult to control, which can easily lead to stress concentration defects. It is impossible to achieve both mechanical strength improvement and heat resistance optimization while maintaining the material's biodegradability.

[0005] Therefore, the development of starch-based materials with high strength, high heat resistance and biodegradability has become a technical problem that the industry urgently needs to overcome. Summary of the Invention

[0006] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a natural ecological biodegradable product and a preparation method thereof.

[0007] A natural ecological biodegradable product, whose raw materials include, by mass, 50-60 parts of starch, 10-20 parts of cellulose fiber, 10-20 parts of polylactic acid, 1-5 parts of phytic acid, 1-2 parts of nano zinc oxide, 1-5 parts of mesoporous silica, 5-10 parts of plasticizer, 3-8 parts of compatibilizer, and 3-5 parts of nucleating agent.

[0008] Preferably, the starch comprises at least one of corn starch, tapioca starch and potato starch.

[0009] Preferably, the cellulose fiber includes at least one of bamboo fiber, hemp fiber and cotton fiber, and has a length of 5-20 mm.

[0010] Preferably, the pore size of mesoporous silica is 10-20 nm and the specific surface area is 800-1200 m 2 / g.

[0011] Preferably, the plasticizer includes at least one of glycerol, tributyl citrate, and epoxidized soybean oil.

[0012] Preferably, the compatibilizer is maleic anhydride grafted polylactic acid.

[0013] Preferably, the nucleating agent is talc or nano calcium carbonate.

[0014] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0015] S1. Dry the starch for 2-4 hours, add cellulose fiber and mix evenly to obtain a mixed fiber material;

[0016] S2, adding phytic acid to water and stirring evenly, adding nano zinc oxide and ultrasonically treating for 10-20 minutes, adjusting the pH of the system to 5-6, stirring at 50-60° C. for 10-20 minutes, adding mesoporous silica and ultrasonically treating for 10-20 minutes, centrifuging, washing, vacuum drying, and crushing to obtain a modifier;

[0017] S3. Dry the polylactic acid for 3-5 hours, add a plasticizer, a compatibilizer, and a nucleating agent in sequence and mix for 5-10 minutes, add the mixed fiber material and continue mixing for 20-30 minutes to obtain a premix; and extrude the premix.

[0018] Preferably, in S2, the ultrasonic treatment frequency after adding nano zinc oxide is 30-40 kHz, and the ultrasonic treatment frequency after adding mesoporous silica is 30-40 kHz.

[0019] Preferably, in S3, the extrusion temperature is 180-200°C. Beneficial effects

[0020] The purpose of the present invention is to provide a natural ecological biodegradable product, which not only has good biodegradability and can be quickly decomposed into harmless substances in the natural environment, but also has excellent mechanical strength and thermal stability, can meet the needs of various usage scenarios, and has a relatively low production cost.

[0021] The present invention uses polylactic acid, starch, and cellulose fiber as its primary raw materials. These materials are highly biodegradable and can be gradually decomposed into harmless substances such as water and carbon dioxide by microorganisms in the natural environment, making them environmentally friendly. The addition of starch and cellulose fiber not only reduces costs but also increases the biodegradation rate of the product. Furthermore, cellulose fiber enhances the mechanical properties of the product, imparting excellent tensile strength, flexural strength, and impact toughness. This makes it suitable for a wide range of applications, including packaging, agriculture, and disposable products.

[0022] The present invention utilizes nano-zinc oxide and the phosphate groups of phytic acid to form a Zn-phytic acid complex. Incompletely coordinated phosphate groups or hydroxyl groups form a hydrogen bond network with PLA. During high-temperature processing, the hydrogen bonds are partially broken at high temperatures, reducing intermolecular forces, lowering melt viscosity, and enhancing fluidity. After cooling, the hydrogen bond network is rebuilt to form a rigid network, thereby improving the heat resistance of the product. Talc powder or nano-calcium carbonate acts as a nucleating agent to promote PLA crystallization, increase crystallinity and heat deformation temperature, and synergize with the Zn-phytic acid complex to enhance shape stability in high-temperature environments (such as microwave heating).

[0023] The present invention uses mesoporous silica to load Zn-phytic acid complexes to achieve nano-scale dispersion, avoid agglomeration during processing, and hinder crack propagation through the pinning effect. In addition, its surface active groups and starch enhance interfacial bonding through hydrogen bond networks and physical anchoring effects, synergistically improving the mechanical properties of the product. While ensuring biodegradability, the mechanical tensile strength of the product is effectively improved, ensuring the comprehensive performance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a comparison chart of the tensile strength and notched impact strength of the products obtained in Example 5 and Comparative Examples 1-3.

[0025] Figure 2 The graph shows the changes in carbon dioxide release using the product obtained in Example 5 as the test material, reference material, and blank container.

[0026] Figure 3 The graph shows the biodegradation rate changes of the product obtained in Example 5 as the test material and the reference material over 156 days. DETAILED DESCRIPTION

[0027] The present invention will be further explained below with reference to specific embodiments.

[0028] The brand of the polylactic acid used below is Unitika, and the model number is HV-6250H. Example 1

[0029] A natural ecological biodegradable product, whose raw materials include: 520g of cassava starch, 120g of flax fiber with a length of 5mm, 100g of polylactic acid, 10g of phytic acid, 10g of nano zinc oxide, 10g of mesoporous silica, 50g of glycerol, 30g of maleic anhydride grafted polylactic acid, and 30g of talc.

[0030] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0031] S1, placing cassava starch in an oven at 80°C for 2 hours, adding hemp fiber and mixing evenly to obtain a mixed fiber material;

[0032] S2. Add phytic acid to 100 g of deionized water and stir evenly. Add nano zinc oxide and ultrasonically treat for 10 min at an ultrasonic frequency of 30 kHz. Adjust the pH of the system to 5-6, stir at 50° C. for 10 min, add mesoporous silica and ultrasonically treat for 10 min at an ultrasonic frequency of 30 kHz. Centrifuge, wash, vacuum dry, and crush to obtain a modifier.

[0033] S3. Put the polylactic acid into a vacuum oven and dry it at a temperature of 60°C for 3 hours. Then add glycerol, maleic anhydride grafted polylactic acid and talcum powder in sequence and add them into a high-speed mixer. Mix at a speed of 800r / min for 5 minutes. Add the mixed fiber material and continue mixing for 20 minutes to obtain a premix. Add the premix into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 180°C and a screw speed of 100r / min, and press into sheets. Example 2

[0034] A natural ecological biodegradable product, whose raw materials include: 580g of potato starch, 200g of cotton fiber with a length of 20mm, 200g of polylactic acid, 50g of phytic acid, 20g of nano zinc oxide, 50g of mesoporous silica, 100g of tributyl citrate, 80g of maleic anhydride grafted polylactic acid, and 50g of nano calcium carbonate.

[0035] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0036] S1, placing potato starch in an oven at 100°C for 4 hours, adding cotton fiber and mixing evenly to obtain a mixed fiber material;

[0037] S2. Add phytic acid to 200 g of deionized water and stir evenly. Add nano zinc oxide and ultrasonically treat for 20 min at an ultrasonic frequency of 40 kHz. Adjust the pH of the system to 5-6, stir at 60° C. for 20 min, add mesoporous silica and ultrasonically treat for 20 min at an ultrasonic frequency of 40 kHz. Centrifuge, wash, vacuum dry, and crush to obtain a modifier.

[0038] S3. Put the polylactic acid into a vacuum oven and dry it at a temperature of 80°C for 5h. Then, tributyl citrate, maleic anhydride grafted polylactic acid and nano-calcium carbonate were added in sequence and added into a high-speed mixer. The mixture was mixed at a speed of 1200r / min for 10min. The mixed fiber material was added and the mixture was continued to mix for 30min to obtain a premix. The premix was added into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 200°C and a screw speed of 300r / min, and then tabletted. Example 3

[0039] A natural ecological biodegradable product, whose raw materials include: 520g corn starch, 120g bamboo fiber with a length of 15mm, 170g polylactic acid, 20g phytic acid, 17g nano zinc oxide, 20g mesoporous silica, 90g epoxy soybean oil, 40g maleic anhydride grafted polylactic acid, and 45g talc.

[0040] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0041] S1, placing corn starch in an oven at 85°C for 3.5 hours, adding bamboo fiber and mixing evenly to obtain a mixed fiber material;

[0042] S2. Add phytic acid to 120 g of deionized water and stir evenly. Add nano zinc oxide and ultrasonically treat for 17 min at an ultrasonic frequency of 33 kHz. Adjust the pH of the system to 5-6, stir at 58° C. for 12 min, add mesoporous silica and ultrasonically treat for 18 min at an ultrasonic frequency of 33 kHz. Centrifuge, wash, vacuum dry, and crush to obtain a modifier.

[0043] S3. Put the polylactic acid into a vacuum oven and dry it at a temperature of 75°C for 3.5 hours. Then add epoxy soybean oil, maleic anhydride grafted polylactic acid and talcum powder in sequence and add them into a high-speed mixer. Mix at a speed of 1100 r / min for 7 minutes. Add the mixed fiber material and continue mixing for 28 minutes to obtain a premix. Add the premix into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 185°C and a screw speed of 250 r / min, and press into sheets. Example 4

[0044] A natural ecological biodegradable product, whose raw materials include: 580g corn starch, 90g hemp fiber and 90g cotton fiber with a length of 10mm, 130g polylactic acid, 40g phytic acid, 13g nano zinc oxide, 40g mesoporous silica, 70g glycerol, 60g maleic anhydride grafted polylactic acid, and 35g nano calcium carbonate.

[0045] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0046] S1. Place corn starch in an oven at 95°C for 2.5 hours, add hemp fiber and cotton fiber and mix evenly to obtain a mixed fiber material;

[0047] S2. Add phytic acid to 180 g of deionized water and stir evenly. Add nano zinc oxide and ultrasonically treat for 13 min at an ultrasonic frequency of 39 kHz. Adjust the pH of the system to 5-6, stir at 52 ° C for 18 min, add mesoporous silica and ultrasonically treat for 12 min at an ultrasonic frequency of 39 kHz, centrifuge, wash, vacuum dry, and crush to obtain a modifier.

[0048] S3. Put the polylactic acid into a vacuum oven and dry it at a temperature of 65°C for 4.5 hours. Then, add glycerol, maleic anhydride grafted polylactic acid, and nano-calcium carbonate in sequence and add them into a high-speed mixer. Mix at a speed of 900 r / min for 9 minutes. Add the mixed fiber material and continue mixing for 22 minutes to obtain a premix. Add the premix into a twin-screw extruder for melt blending and extrusion. The extrusion temperature is 195°C and the screw speed is 150 r / min. The premix is ​​then pressed into sheets. Example 5

[0049] A natural ecological biodegradable product, whose raw materials include: 550g corn starch, 100g bamboo fiber with a length of 12mm, 50g hemp fiber with a length of 12mm, 150g polylactic acid, 30g phytic acid, 15g nano zinc oxide, 30g mesoporous silica, 40g tributyl citrate, 40g epoxy soybean oil, 50g maleic anhydride grafted polylactic acid, and 40g talc.

[0050] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0051] S1. Place corn starch in an oven at 90°C for 3 hours, add bamboo fiber and hemp fiber and mix evenly to obtain a mixed fiber material;

[0052] S2. Add phytic acid to 150 g of deionized water and stir evenly. Add nano zinc oxide and ultrasonically treat for 15 min at an ultrasonic frequency of 36 kHz. Adjust the pH of the system to 5-6, stir at 55 ° C for 15 min, add mesoporous silica and ultrasonically treat for 15 min at an ultrasonic frequency of 36 kHz, centrifuge, wash, vacuum dry, and crush to obtain a modifier.

[0053] S3. Put the polylactic acid into a vacuum oven and dry it at 70°C for 4 hours. Then add tributyl citrate, epoxy soybean oil, maleic anhydride grafted polylactic acid and talcum powder in sequence and add them into a high-speed mixer. Mix at a speed of 1000 r / min for 8 minutes. Add the mixed fiber material and continue mixing for 25 minutes to obtain a premix. Add the premix into a twin-screw extruder for melt blending and extrusion. The extrusion temperature is 190°C and the screw speed is 200 r / min. The premix is ​​then pressed into sheets. Comparative Example 1

[0054] A natural ecological biodegradable product, whose raw materials include: 550g corn starch, 100g bamboo fiber with a length of 12mm, 50g hemp fiber with a length of 12mm, 150g polylactic acid, 30g phytic acid, 15g nano zinc oxide, 30g mesoporous silica, 40g tributyl citrate, 40g epoxy soybean oil, 50g maleic anhydride grafted polylactic acid, and 40g talc.

[0055] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0056] S1. Place corn starch in an oven at 90°C for 3 hours, add bamboo fiber and hemp fiber and mix evenly to obtain a mixed fiber material;

[0057] S2. Add phytic acid to 150 g of deionized water and stir evenly, add nano zinc oxide and ultrasonically treat for 15 min at an ultrasonic frequency of 36 kHz, adjust the pH of the system to 5-6, stir at a temperature of 55° C. for 15 min, centrifuge, wash, vacuum dry, and crush to obtain a modifier;

[0058] S3. Put the polylactic acid into a vacuum oven and dry it at 70°C for 4 hours. Then add tributyl citrate, epoxy soybean oil, mesoporous silica, maleic anhydride grafted polylactic acid and talc in sequence and add them into a high-speed mixer. Mix at a speed of 1000 r / min for 8 minutes. Add the mixed fiber material and continue mixing for 25 minutes to obtain a premix. Add the premix into a twin-screw extruder for melt blending and extrusion. The extrusion temperature is 190°C and the screw speed is 200 r / min. The premix is ​​then pressed into sheets. Comparative Example 2

[0059] A natural ecological biodegradable product, whose raw materials include: 550g corn starch, 150g polylactic acid, 30g phytic acid, 15g nano zinc oxide, 30g mesoporous silica, 40g tributyl citrate, 40g epoxy soybean oil, 50g maleic anhydride grafted polylactic acid, and 40g talc.

[0060] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0061] S1, placing corn starch in an oven at 90°C for 3 hours;

[0062] S2. Add phytic acid to 150 g of deionized water and stir evenly. Add nano zinc oxide and ultrasonically treat for 15 min at an ultrasonic frequency of 36 kHz. Adjust the pH of the system to 5-6, stir at 55 ° C for 15 min, add mesoporous silica and ultrasonically treat for 15 min at an ultrasonic frequency of 36 kHz, centrifuge, wash, vacuum dry, and crush to obtain a modifier.

[0063] S3. Put the polylactic acid into a vacuum oven and dry it at 70°C for 4 hours. Then, add tributyl citrate, epoxy soybean oil, maleic anhydride grafted polylactic acid and talcum powder in sequence and add them into a high-speed mixer. Mix at a speed of 1000 r / min for 8 minutes. Add the oven-treated corn starch and continue mixing for 25 minutes to obtain a premix. Add the premix into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 190°C and a screw speed of 200 r / min, and press into sheets. Comparative Example 3

[0064] A natural ecological biodegradable product, whose raw materials include: 550g corn starch, 100g bamboo fiber with a length of 12mm, 50g hemp fiber with a length of 12mm, 150g polylactic acid, 30g phytic acid, 15g nano zinc oxide, 30g mesoporous silica, 40g tributyl citrate, 40g epoxy soybean oil, and 50g maleic anhydride grafted polylactic acid.

[0065] The method for preparing the above-mentioned natural ecological biodegradable product comprises the following steps:

[0066] S1. Place corn starch in an oven at 90°C for 3 hours, add bamboo fiber and hemp fiber and mix evenly to obtain a mixed fiber material;

[0067] S2. Add phytic acid to 150 g of deionized water and stir evenly. Add nano zinc oxide and ultrasonically treat for 15 min at an ultrasonic frequency of 36 kHz. Adjust the pH of the system to 5-6, stir at 55 ° C for 15 min, add mesoporous silica and ultrasonically treat for 15 min at an ultrasonic frequency of 36 kHz, centrifuge, wash, vacuum dry, and crush to obtain a modifier.

[0068] S3. Put the polylactic acid into a vacuum oven and dry it at 70°C for 4 hours. Then, add tributyl citrate, epoxy soybean oil, and maleic anhydride-grafted polylactic acid in sequence and add them into a high-speed mixer. Mix at a speed of 1000 r / min for 8 minutes. Add the mixed fiber material and continue mixing for 25 minutes to obtain a premix. Add the premix into a twin-screw extruder for melt blending and extrusion at an extrusion temperature of 190°C and a screw speed of 200 r / min, and press into sheets.

[0069] The tensile strength of the products obtained in Example 5 and Comparative Examples 1-3 was measured with reference to GB / T 1040.4-2006, "Plastics — Determination of tensile properties — Part 4: Test conditions for isotropic and orthotropic fiber-reinforced composite materials." The notched impact strength of the products obtained in Example 5 and Comparative Examples 1-3 was measured with reference to GB / T 1043.1-2008, "Plastics — Determination of impact properties of charpy beams — Part 1: Non-instrumented impact test."

[0070] like Figure 1 As shown, the tensile strength and notched impact strength of the sheet obtained in Example 5 are both the highest, and are significantly better than those of Comparative Examples 1-3 by chi-square test.

[0071] The products obtained in Example 5 and Comparative Examples 1-3 were vacuum-formed to prepare lunch boxes.

[0072] The above-mentioned lunch boxes were tested for evaporation residue (water 60℃×2h, 4% acetic acid 60℃×2h, 65% ethanol 20℃×2h, n-hexane 20℃×2h), and the results were all ≤5mg / L, which met the corresponding standards.

[0073] The above-mentioned lunch boxes were tested for heavy metals (measured in Pb or As, 4% acetic acid at 60℃×2h), and the results showed that no heavy metals were detected, which met the relevant standards.

[0074] The above-mentioned lunch boxes were subjected to decolorization tests (wiping with ethanol solution (65+35), soaking in water at 60℃×2h, soaking in 4% acetic acid at 60℃×2h, soaking in 65% ethanol at 20℃×2h, and soaking in n-hexane at 20℃×2h), and the results were all negative, meeting the corresponding standards.

[0075] The above-mentioned lunch boxes were tested for olefin polymers (n-hexane extract, xylene extract), and the results all met the corresponding standards.

[0076] The above lunch box was subjected to performance testing, and the test results are shown in Table 1 below:

[0077] Table 1 Performance test of lunch boxes obtained in Example 5 and Comparative Examples 1-3

[0078]

[0079] From the test results, it can be seen that the mechanical properties of the product obtained in Example 5 are better than those of Comparative Examples 1-3.

[0080] In view of the fact that the product obtained in Example 5 has the best mechanical properties, this application uses the sheet obtained in Example 5 as the test material and thin-layer chromatography-grade cellulose as the reference material, and conducts a 156-day composting degradation experiment with reference to GB / T 19277.1-2011 "Determination of the ultimate aerobic biodegradability of materials under controlled composting conditions by measuring the released carbon dioxide - Part 1: General method" (the dry weight ratio of compost to test material / reference material is approximately 6:1, and aeration treatment is performed with de-CO2 air so that the oxygen concentration discharged from each compost container is not less than 6%. The test is carried out at 58±2°C and in the dark; the CO2 release is determined by titration).

[0081] The cumulative carbon dioxide release and biodegradation rate of the test materials are shown in Table 2 below.

[0082] Table 2 Cumulative carbon dioxide release and biodegradation rate of test materials

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] In Table 2, (CO2) B,mean The average amount of carbon dioxide released by the blank containers, in grams per container (g / container); (CO2) t1 、(CO2) t2 and (CO2) t3 The cumulative amount of carbon dioxide released from the compost containers containing the test mixture in three parallel groups, in grams per container (g / container); (CO2) t,mean D is the average value of the cumulative carbon dioxide released from the compost containers containing the test materials in the three parallel groups of test materials, in grams per container (g / container); t1 、D t2 and D t3 are the biodegradation rates of three parallel groups of test materials; D t,mean It is the average biodegradation rate of three parallel groups of test materials.

[0089] like Figure 2As shown in the graph, the carbon dioxide emission of the reference material stopped increasing significantly around the 70th day and began to maintain a slight increase; however, the carbon dioxide emission of the test material maintained a significant upward trend within 156 days, indicating that the product obtained by the present invention continued to be efficiently decomposed during the composting degradation experiment.

[0090] like Figure 3 As shown in the figure, the biodegradation rate of the reference material was 74.60% on the 45th day and 93.20% on the 156th day; while the biodegradation rate of the test material was 84.80% on the 156th day, and the relative decomposition rate on the 156th day was 91.00%, which confirmed that the product obtained by the present invention has good biodegradability.

[0091] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A natural ecological biodegradable product, characterized in that: The raw materials include, by mass: 50-60 parts of starch, 10-20 parts of cellulose fiber, 10-20 parts of polylactic acid, 1-5 parts of phytic acid, 1-2 parts of nano zinc oxide, 1-5 parts of mesoporous silica, 5-10 parts of plasticizer, 3-8 parts of compatibilizer, and 3-5 parts of nucleating agent; The method for preparing the natural ecological biodegradable product comprises the following steps: S1. Dry the starch for 2-4 hours, add cellulose fiber and mix evenly to obtain a mixed fiber material; S2, adding phytic acid to water and stirring evenly, adding nano zinc oxide and ultrasonically treating for 10-20 minutes, adjusting the pH of the system to 5-6, stirring at 50-60° C. for 10-20 minutes, adding mesoporous silica and ultrasonically treating for 10-20 minutes, centrifuging, washing, vacuum drying, and crushing to obtain a modifier; S3. Dry the polylactic acid for 3-5 hours, add a plasticizer, a compatibilizer, and a nucleating agent in sequence and mix for 5-10 minutes, add the mixed fiber material and continue mixing for 20-30 minutes to obtain a premix; and extrude the premix.

2. The natural ecological biodegradable product according to claim 1, characterized in that: Starches include: At least one of corn starch, tapioca starch, and potato starch.

3. The natural ecological biodegradable product according to claim 1, characterized in that: The cellulose fiber includes at least one of bamboo fiber, hemp fiber and cotton fiber, and has a length of 5-20 mm.

4. The natural ecological biodegradable product according to claim 1, characterized in that: The pore size of mesoporous silica is 10-20nm and the specific surface area is 800-1200m 2 / g.

5. The natural ecological biodegradable product according to claim 1, characterized in that: Plasticizers include: At least one of glycerin, tributyl citrate, and epoxidized soybean oil.

6. The natural ecological biodegradable product according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted polylactic acid.

7. The natural ecological biodegradable product according to claim 1, characterized in that: The nucleating agent is talc or nano calcium carbonate.

8. A method for preparing the natural ecological biodegradable product according to any one of claims 1 to 7, characterized in that: The steps include: S1. Dry the starch for 2-4 hours, add cellulose fiber and mix evenly to obtain a mixed fiber material; S2, adding phytic acid to water and stirring evenly, adding nano zinc oxide and ultrasonically treating for 10-20 minutes, adjusting the pH of the system to 5-6, stirring at 50-60° C. for 10-20 minutes, adding mesoporous silica and ultrasonically treating for 10-20 minutes, centrifuging, washing, vacuum drying, and crushing to obtain a modifier; S3. Dry the polylactic acid for 3-5 hours, add a plasticizer, a compatibilizer, and a nucleating agent in sequence and mix for 5-10 minutes, add the mixed fiber material and continue mixing for 20-30 minutes to obtain a premix; and extrude the premix.

9. The method for preparing the natural ecological biodegradable product according to claim 8, characterized in that: In S2, the ultrasonic treatment frequency is 30-40 kHz after the addition of nano zinc oxide, and the ultrasonic treatment frequency is 30-40 kHz after the addition of mesoporous silica.

10. The method for preparing the natural ecological biodegradable product according to claim 8, characterized in that: In S3, the extrusion temperature is 180-200°C.

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