Ecological environment-friendly microbial degradation mulching film and preparation process thereof

Abstract

The invention relates to the technical field of agriculture, and discloses an ecological environment-friendly microbial degradation mulching film which comprises the following components in percentage by mass: 50-65% of polylactic acid; 15% to 25% of lignocellulose; 5%-10% of glycerin; 0.5%-2% of nano titanium dioxide; 0.1% to 0.5% of silver nanoparticles; 0.5%-2% of a tea tree oil extract; 15% to 20% of carboxymethyl cellulose; 13%-15% of a plant growth regulator; 5%-10% of an auxiliary agent; the auxiliary agent comprises one or more of an antioxidant, a plasticizer and a light stabilizer, and the plant growth regulator comprises one or more of a seaweed extract, indoleacetic acid or oleanolic acid. By adding nano titanium dioxide and silver nanoparticles into the mulching film, excellent ultraviolet resistance and antibacterial performance of the mulching film are achieved, and the problem that aging of a traditional mulching film is accelerated due to ultraviolet irradiation is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of agriculture, and particularly to an eco-friendly microbial degradable mulching film and its preparation process. Background Art

[0002] With the continuous development of agricultural production, the application of mulching film technology has become one of the important means to improve crop yields, protect the soil, conserve water and maintain soil moisture. However, with the changes in the agricultural environment and the enhancement of eco-friendly awareness, traditional mulching films are facing more and more problems, especially in terms of environmental protection, service life and promotion of plant growth, and there is an urgent need for improvement.

[0003] First of all, most of the existing traditional mulching films use polyethylene (PE) or polypropylene (PP) as the main raw materials. These materials have good heat preservation and waterproof properties, but they are prone to accelerated aging under ultraviolet irradiation, resulting in a short service life of the mulching film. Under the long-term action of ultraviolet rays, traditional mulching films will not only become brittle and easy to break, but may also release harmful substances, affecting crop growth and soil environment. Therefore, the poor ultraviolet resistance of traditional mulching films limits their long-term application in agriculture.

[0004] Secondly, traditional plastic mulching films are difficult to degrade during use. Especially when not recycled after use, they will cause serious environmental pollution. It is difficult to handle plastic mulching films in agricultural waste treatment. Many plastic mulching films eventually enter landfills or the environment and cannot be degraded for a long time, posing potential hazards to the soil and water environment. With the increasingly strict environmental protection regulations, the development of mulching films that can be naturally degraded has become the focus of current technical research.

[0005] In addition, although traditional mulching films play a role in protecting crops and reducing water evaporation to a certain extent, their ability to regulate crop growth and adapt to the environment is weak. Especially in adverse climates or extreme environments, the use effect of mulching films far from meets the expectations, and it cannot effectively promote the root growth of plants or enhance the stress resistance of crops. Therefore, how to improve the supporting effect of mulching films on plants while ensuring the crop growth environment has become another direction for the development of mulching film technology. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides an eco-friendly microbial degradable mulching film and its preparation process, which solves the problems existing in the service life, degradability and crop growth support of traditional mulching films.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: An eco-friendly microbial degradable mulching film, including the following mass percentages: 50%-65% polylactic acid; 15%-25% lignocellulose; 5% - 10% glycerol; 0.5% - 2% nano - titanium dioxide; 0.1% - 0.5% silver nanoparticles; 0.5% - 2% tea tree oil extract; 15% - 20% carboxymethyl cellulose; 13% - 15% plant growth regulator; 5% - 10% auxiliary agent.

[0008] Preferably, the auxiliary agent includes one or more of antioxidant, plasticizer and light stabilizer, and the plant growth regulator includes one or more of seaweed extract, indole - 3 - acetic acid or oleanolic acid.

[0009] A preparation method of an eco - friendly microbe - degradable mulching film, comprising the following steps: S1. Dissolve polylactic acid, lignocellulose and glycerol in a solvent to obtain a homogeneous solution; S2. Add nano - titanium dioxide, silver nanoparticles, tea tree oil extract and carboxymethyl cellulose into the solution and stir evenly to obtain a composite solution; S3. Uniformly coat or impregnate the composite solution on a polylactic acid film to form a composite film; S4. Perform a drying treatment on the composite film; S5. Perform ultraviolet irradiation on the dried composite film to obtain the mulching film.

[0010] Preferably, in the S1 step, the solvent includes chloroform or dichloromethane, and its dosage is 10% - 20% of the total mass of polylactic acid and lignocellulose.

[0011] Preferably, in the S3 step, ultrasonic treatment is adopted during the stirring of the composite solution, the treatment frequency is 20 kHz to 40 kHz, and the treatment time is 5 minutes to 10 minutes.

[0012] Preferably, in the S3 step, the coating or impregnation time is 30 minutes to 60 hours to form a uniform coating.

[0013] Preferably, the S4 step includes: Place the coated or impregnated film in a constant - temperature and constant - humidity drying chamber, the drying temperature is 40°C to 60°C, the humidity is controlled between 40% - 60%, and the drying time is 4 hours to 8 hours.

[0014] Preferably, in the S5 step, the wavelength band of the ultraviolet irradiation is 315 - 400 nm, the ultraviolet intensity is 10 mW / cm² to 50 mW / cm², and the irradiation time is 30 minutes.

[0015] Preferably, the thickness of the composite film is 20 μm to 100 μm, and the thickness uniformity error of the film does not exceed 5%.

[0016] Preferably, the addition ratio of polylactic acid, lignocellulose and glycerol in S1 is 4:1:1 to 6:2:1, and the addition ratio of nano-titanium dioxide, silver nanoparticles, tea tree oil extract and carboxymethyl cellulose in S2 is 3:0.5:2:4 to 5:1:3:6.

[0017] The present invention provides an eco-friendly microbe-degradable ground film and a preparation process. It has the following beneficial effects: 1. By adding nano-titanium dioxide and silver nanoparticles to the ground film, the present invention realizes excellent anti-ultraviolet and antibacterial properties of the ground film, and solves the problem that traditional ground films are accelerated in aging due to ultraviolet irradiation. Through this innovation, a ground film with long-term anti-ultraviolet and antibacterial functions is obtained, effectively extending the service life of the ground film and reducing the harm of ultraviolet rays to the soil and crops.

[0018] 2. By using polylactic acid and lignocellulose as the main components, the present invention realizes the effect of rapid degradation in the natural environment, and solves the problem that traditional plastic ground films are difficult to degrade and cause environmental pollution. Through this technological innovation, an eco-friendly microbe-degradable ground film is obtained, significantly reducing the negative impact of agricultural waste on the environment.

[0019] 3. By adding plant growth regulators such as seaweed extract and indoleacetic acid, the present invention realizes the effect of promoting plant root growth and enhancing crop stress resistance in adverse environments, and solves the problem that traditional ground films cannot effectively promote plant growth. Through this technological innovation, a ground film that can significantly improve crop stress resistance and growth is obtained, improving the efficiency of agricultural production and the quality of crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the steps of the preparation method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Please refer to the attached Figure 1, the present invention provides an eco-friendly microbe-degradable ground film, comprising the following mass percentages: 50%-65% of polylactic acid; 15%-25% of lignocellulose; 5%-10% of glycerol; 0.5%-2% of nano-titanium dioxide; 0.1%-0.5% of silver nanoparticles; 0.5%-2% of tea tree oil extract; 15%-20% of carboxymethyl cellulose; 13%-15% of plant growth regulator; 5%-10% of additives.

[0023] The additives include one or more of antioxidant, plasticizer and light stabilizer, and the plant growth regulator includes one or more of seaweed extract, indoleacetic acid or oleanolic acid.

[0024] A preparation method of an eco-friendly microbe-degradable ground film, comprising the following steps: S1. Dissolve polylactic acid, lignocellulose and glycerol in a solvent to obtain a homogeneous solution; S2. Add nano-titanium dioxide, silver nanoparticles, tea tree oil extract and carboxymethyl cellulose into the solution and stir evenly to obtain a composite solution; S3. Uniformly coat or impregnate the composite solution on a polylactic acid film to form a composite film; S4. Perform a drying treatment on the composite film; S5. Perform ultraviolet irradiation on the dried composite film to obtain the ground film.

[0025] Specifically, its main materials and sources are as follows: Polylactic acid (PLA) (50%-65%) is derived from lactic acid produced by fermenting corn starch or sugarcane, and is formed through a polymerization reaction. It serves as the base film material to provide strength and degradability; Wood plastic composite (WPC) (15%-25%) is extracted from agricultural waste such as rice husks, corn straws or wood processing residues, which can enhance mechanical strength and accelerate biodegradation; Glycerol (5%-10%) is usually separated after saponifying vegetable oils (such as palm oil or soybean oil), and is used as a plasticizer to improve the flexibility of the film; Nano titanium dioxide (0.5%-2%) is mainly prepared from titanium ore by the sulfuric acid method or the chlorination method, and has excellent ultraviolet resistance; Silver nanoparticles (0.1%-0.5%) are prepared from silver nitrate by chemical reduction method, which can inhibit the growth of bacteria and fungi and improve the antibacterial performance of the film; Tea tree oil extract (0.5%-2%) is distilled from Australian tea tree leaves and has natural antibacterial and antiseptic effects to reduce microbial erosion; Carboxymethyl cellulose (15%-20%) is usually prepared by chemically modifying wood pulp or cotton cellulose, and is used as a thickening agent and stabilizer to enhance the toughness and hygroscopicity of the film; Plant growth regulators (13%-15%) include seaweed extracts (extracted from deep-sea brown algae), indole-3-acetic acid (IAA, derived from plant hormones), and oleanolic acid (extracted from olive leaves or plants of the Gentianaceae family), which are used to promote plant growth and improve the stress resistance of crops. In addition, additives (5%-10%) include antioxidants, plasticizers and light stabilizers, which are usually obtained from chemical suppliers to improve the weather resistance and stability of the plastic film.

[0026] The method for preparing the plastic film of the present invention includes the following steps: First, in step S1, 50 grams of PLA, 20 grams of WPC and 10 grams of glycerol are added to 250 ml of dichloromethane solvent, the temperature is controlled at 40°C, and stirred until uniform, and then stirred at 45°C and 300 rpm for 40 minutes to ensure complete dissolution. After entering step S2, 2 grams of nano titanium dioxide, 0.5 grams of silver nanoparticles, 1 gram of tea tree oil extract, and 10 grams of carboxymethyl cellulose are successively added to the solution, and ultrasonic treatment (30 kHz, 8 minutes) is used to ensure uniform dispersion. Subsequently, in step S3, the composite solution is applied to the polylactic acid film by a coating or dipping method. When coating, the thickness is controlled at 40 μm and the coating speed is 8 cm / s to ensure uniformity; for the dipping method, the film needs to be completely immersed in the solution for 30 minutes to ensure sufficient penetration of the solution.

[0027] In step S4, the treated film is placed in a constant temperature drying chamber at 50°C, the humidity is maintained at 50%, and the drying time is set to 6 hours to ensure that the film is completely cured and there is no solvent residue on the surface. Finally, in step S5, the dried film is irradiated with ultraviolet light (wavelength range 315-400 nm, intensity 30 mW / cm², time 30 minutes) to enhance its ultraviolet resistance and improve its aging resistance under strong light conditions.

[0028] Based on the above base materials and preparation methods, the following examples are given: Example 1: Preparation of an eco-friendly microbe-degradable mulch film with high biodegradability and UV resistance Step 1: Dissolution and mixing Take 50 grams of polylactic acid (PLA) and 20 grams of wood pulp cellulose (WPC), and add them to 100 ml of chloroform solvent.

[0029] Add 10 grams of glycerol (Glycol), and stir until completely dissolved. The dissolution temperature is controlled at 45 °C, the stirring speed is set at 300 rpm, and it lasts for 40 minutes.

[0030] Step 2: Adding functional components Add 1 gram of titanium dioxide nanoparticles (TiO2), 0.2 grams of silver nanoparticles (AgNPs), 1 gram of tea tree oil extract, and 6 grams of carboxymethyl cellulose (CMC) to the solution in proportion.

[0031] Use an ultrasonic device with a frequency set at 25 kHz and a treatment time of 7 minutes to ensure the uniformity of the solution.

[0032] Step 3: Coating or impregnating the film Immerse the polylactic acid film in the composite solution for 40 minutes to ensure complete penetration of the film.

[0033] After taking it out, gently remove the excess solution and place it on a clean flat surface.

[0034] Step 4: Drying treatment Put the coated film into a constant temperature and humidity drying chamber with the temperature set at 50 °C and the humidity controlled at 50%. The drying time is 6 hours.

[0035] Step 5: UV irradiation Put the dried film into a UV irradiation chamber, use a UV-A light source with a wavelength range of 315 - 400 nm, set the UV intensity at 30 mW / cm², and irradiate for 30 minutes.

[0036] Example 2: Preparation of an eco-friendly microbe-degradable mulch film with high antibacterial performance Step 1: Dissolving the base film material Take 60 grams of polylactic acid (PLA) and 15 grams of wood pulp cellulose (WPC), add them to 200 ml of dichloromethane solvent, and stir until completely dissolved.

[0037] Continue to add 8 grams of glycerol, keep the temperature at 50 °C, the stirring speed at 350 rpm, and the dissolution time at 45 minutes.

[0038] Step 2: Add antibacterial and plant growth regulators Add 2 grams of seaweed extract and 0.1 gram of indole-3-acetic acid (IAA) to the solution, and then add 0.5 gram of silver nanoparticles (AgNPs).

[0039] Stir with a magnetic stirrer at room temperature for 30 minutes to ensure uniform mixing of the components.

[0040] Step 3: Coating the film Coat the composite solution on a layer of polylactic acid film with a coating thickness of about 40 μm.

[0041] Set the coating time to 30 minutes to ensure an even coating.

[0042] Step 4: Drying and shaping Put the coated film into a drying chamber, set the drying temperature to 45 °C, and keep the humidity at 45%.

[0043] Set the drying time to 5 hours until the film surface is completely dry and shaped.

[0044] Step 5: UV irradiation Use a UV-B light source (wavelength range 280 - 320 nm), with a UV intensity of 20 mW / cm² and an irradiation time of 40 minutes.

[0045] Example 3: Preparation of a microbially degradable mulch film for promoting plant growth and improving stress resistance Step 1: Dissolution of the base film Take 55 grams of polylactic acid (PLA) and 18 grams of wood pulp cellulose (WPC), add them to 120 ml of chloroform, and stir until completely dissolved.

[0046] Add 7 grams of glycerol (Glycol), and continue stirring until the solution is homogeneous. Set the dissolution temperature to 48 °C, the stirring speed to 250 rpm, and continue for 35 minutes.

[0047] Step 2: Adding plant growth regulators Add 1.5 grams of seaweed extract and 1 gram of indole-3-acetic acid (IAA) to the solution.

[0048] Set the stirring time to 25 minutes to ensure complete dissolution of the plant growth regulators and uniform integration with the base film material.

[0049] Step 3: Coating or impregnating the film Uniformly coat the composite solution on the polylactic acid film, and the coating time is 45 minutes.

[0050] Then let the film dry naturally in the air and keep it in an environment of 28 °C.

[0051] Step 4: Drying treatment Place it in a drying chamber, set the drying temperature to 55 °C, and control the humidity at 50%. The drying time is 6 hours.

[0052] Step 5: Ultraviolet irradiation Use a UV-A light source with a wavelength range of 315 - 400 nm and an ultraviolet intensity of 40 mW / cm² for 30 minutes.

[0053] Example 4: Preparation of a mulch film with high ultraviolet resistance and good degradability Step 1: Dissolve polylactic acid and wood cellulose Take 65 grams of polylactic acid (PLA) and 17 grams of wood cellulose (WPC), add them to 250 ml of dichloromethane solvent, and stir until completely dissolved.

[0054] Add 9 grams of glycerol, dissolve at a temperature of 50 °C, stir at a speed of 300 rpm for 45 minutes.

[0055] Step 2: Add titanium dioxide nanoparticles and carboxymethyl cellulose Add 2 grams of titanium dioxide nanoparticles (TiO2) and 8 grams of carboxymethyl cellulose (CMC) to the solution.

[0056] Use ultrasonic treatment at a frequency of 30 kHz for 10 minutes to ensure uniform dispersion of the components.

[0057] Step 3: Coating the film Uniformly coat the composite solution on the film for 35 minutes to ensure a uniform film layer.

[0058] Step 4: Drying treatment Put the coated film into a drying chamber, set the temperature to 48 °C, and control the humidity at 50%. The drying time is 5 hours.

[0059] Step 5: Ultraviolet irradiation Use a UV-A light source with a wavelength range of 315 - 400 nm and an ultraviolet intensity of 30 mW / cm² for 30 minutes.

[0060] Comparative Example 1: Comparative experiment without using titanium dioxide nanoparticles (TiO2) In this comparative example, other formulations and processes in Example 1 are maintained, but titanium dioxide nanoparticles are not added to compare the change in its ultraviolet resistance.

[0061] S1: Dissolve the base film material Dissolve 50 grams of polylactic acid (PLA) and 20 grams of wood cellulose (WPC) in 250 ml of dichloromethane solvent, and stir until completely dissolved.

[0062] Add 10 grams of glycerol, at a temperature of 45 °C, with a stirring speed of 300 rpm, for 40 minutes.

[0063] S2: Add antibacterial components Stir 0.5 grams of silver nanoparticles, 1 gram of tea tree oil extract, and 6 grams of carboxymethyl cellulose for 30 minutes to ensure uniform dispersion of the solution. (No nano-titanium dioxide was added in this comparative example) S3: Coating or impregnating the film Use the coating method with a film thickness of 40 μm, or use the impregnation method for 40 minutes.

[0064] S4: Drying treatment Dry in an environment of 50 °C and 50% humidity for 6 hours.

[0065] S5: UV irradiation UV-A light source, 315 - 400 nm, UV intensity 30 mW / cm², irradiate for 30 minutes.

[0066] Comparative Example 2: Comparative experiment without using silver nanoparticles (AgNPs) In this comparative example, other formulations and processes of Example 2 were maintained, but silver nanoparticles were not added to compare the changes in antibacterial properties.

[0067] S1: Dissolve the base film material Dissolve 60 grams of polylactic acid (PLA) and 15 grams of wood pulp cellulose (WPC) in 200 ml of dichloromethane solvent and stir until completely dissolved.

[0068] Add 8 grams of glycerol, at a temperature of 50 °C, with a stirring speed of 350 rpm, for 45 minutes.

[0069] S2: Add UV-resistant components Stir 2 grams of nano-titanium dioxide, 1 gram of tea tree oil extract, and 10 grams of carboxymethyl cellulose for 30 minutes. (No silver nanoparticles were added in this comparative example) S3: Coating the film Use the coating method with a film thickness of 40 μm and a coating time of 30 minutes.

[0070] S4: Drying treatment Dry at 45 °C for 5 hours.

[0071] S5: UV irradiation UV-B light source (280 - 320 nm), UV intensity 20 mW / cm², irradiate for 40 minutes.

[0072] Comparative Example 3: Comparative experiment without plant growth regulators This comparative example keeps the other formulations and processes in Example 3 unchanged, but does not add plant growth regulators to compare the changes in plant root growth.

[0073] S1: Dissolution of the base film 55 g of polylactic acid (PLA) and 18 g of wood pulp cellulose (WPC) are added to 120 ml of chloroform solution and stirred until completely dissolved.

[0074] 7 g of glycerol is added, the temperature is 48 °C, the stirring speed is 250 rpm, and it lasts for 35 minutes.

[0075] S2: Addition of other functional components 2 g of nano-titanium dioxide, 0.5 g of silver nanoparticles, 1 g of tea tree oil extract, and 8 g of carboxymethyl cellulose are stirred for 25 minutes. (No plant growth regulator is added in this comparative example) S3: Coating the film The impregnation method is used and impregnated for 45 minutes to ensure uniform penetration of the material.

[0076] S4: Drying treatment Dried at 55 °C for 6 hours with a humidity of 50%.

[0077] S5: UV irradiation UV-A light source, UV intensity 40 mW / cm², irradiated for 30 minutes.

[0078] Comparative Example 4: Comparative experiment without carboxymethyl cellulose (CMC) This comparative example keeps the other formulations and processes in Example 4 unchanged, but does not add carboxymethyl cellulose to compare the stability and waterproof ability of the film.

[0079] S1: Dissolving the base film material 65 g of polylactic acid (PLA) and 17 g of wood pulp cellulose (WPC) are added to 250 ml of dichloromethane solvent and stirred until completely dissolved.

[0080] 9 g of glycerol is added, the temperature is 50 °C, the stirring speed is 300 rpm, and it lasts for 45 minutes.

[0081] S2: Adding functional components 2 g of nano-titanium dioxide, 0.5 g of silver nanoparticles, 1 g of tea tree oil extract are ultrasonically treated (30 kHz, 10 minutes). (No carboxymethyl cellulose is added in this comparative example) S3: Coating the film The coating method is used, the film thickness is 40 μm, and the coating time is 35 minutes.

[0082] S4: Drying treatment Dried at 50 °C for 5 hours.

[0083] S5: UV irradiation UV-A light source, wavelength range 315 - 400 nm, UV intensity 30 mW / cm², irradiation time 30 minutes.

[0084] Comparative Example 5: Comparative experiment using traditional polyethylene (PE) plastic mulch film This comparative example uses traditional polyethylene (PE) plastic mulch film without biodegradable materials to compare its degradability and environmental protection performance.

[0085] S1: Preparation of polyethylene film Commercial polyethylene (PE) pellets are used to prepare the film by the melt blowing method.

[0086] Melting temperature 180 °C, extrusion speed 3 m / min, film thickness 40 μm.

[0087] S2: Coating process Without adding any biodegradable components, only 2 grams of nano-titanium dioxide and 0.5 grams of silver nanoparticles are surface-coated to enhance weather resistance.

[0088] S3: Drying and irradiation Dried at 60 °C for 4 hours, UV irradiation at 50 mW / cm² for 40 minutes to simulate the outdoor environment.

[0089] Experimental design: Experiment 1: Test of anti-UV aging performance This experiment aims to evaluate the aging of different mulch film samples under UV irradiation conditions, and focuses on observing the role of nano-titanium dioxide (TiO2) in improving the anti-UV ability. Example 1 (containing TiO2), Comparative Example 1 (without TiO2) and Comparative Example 5 (traditional PE mulch film) are selected for testing to compare their durability and aging degree in the UV environment.

[0090] Experimental procedure Sample preparation: Cut mulch film test pieces with a size of 10 cm × 10 cm, ensuring no creases. Labeled as A (Example 1), B (Comparative Example 1), C (Comparative Example 5).

[0091] UV irradiation: Fix the samples in the UV aging test chamber, use a UV-A light source (315 - 400 nm), and set the UV intensity to 30 mW / cm² to simulate the sunlight irradiation environment.

[0092] Aging test cycle: The test lasts for 14 days, and samples are taken every 48 hours to observe the changes on the film surface.

[0093] Tensile strength test: Use an electronic tensile testing machine to measure the tensile strength of the samples and record the numerical changes.

[0094] Microstructural analysis: The surface micro-changes of the samples were observed using a scanning electron microscope (SEM) to analyze the cracks and degradation conditions.

[0095] Color change recording: A color difference meter was used to measure the color change (ΔE value) of the samples, and the fading degree at different time points was recorded.

[0096] Data analysis: The aging degrees of different samples were compared, and combined with the microstructural changes, the contribution of TiO2 to the UV resistance performance was analyzed.

[0097] Note: The ΔE value represents the color change, and the larger the value, the more serious the fading.

[0098] The key to improving the UV resistance performance of the mulch film lies in the introduction of nano-titanium dioxide. As a UV absorber, TiO2 converts high-energy ultraviolet light into low-energy heat through an energy conversion mechanism, avoiding the breakage of chemical bonds inside the film material. Experimental data show that the crack growth in Example 1 is slow, and the decrease in tensile strength is relatively small, while obvious aging signs appear in Comparative Example 1 without adding TiO2 and the traditional PE mulch film. The impact of ultraviolet rays on polymer materials will lead to the generation of free radicals, triggering oxidative degradation. The shielding effect of TiO2 effectively inhibits this process, enabling the film material to remain stable under long-term irradiation.

[0099] The color change (ΔE) further confirms the role of TiO2. For Comparative Example 1 without adding TiO2, the ΔE value rises sharply within a short time, and the film material fades severely, indicating that ultraviolet rays cause pigment decomposition and material degradation. The ΔE change in Example 1 is slow, meaning that TiO2 significantly improves the weather resistance of the film by reducing the photoaging rate. In addition, the traditional PE mulch film has worse UV resistance, and the crack propagation is the fastest, which is related to the lack of a UV shielding mechanism in PE itself and is prone to degradation and pulverization in the outdoor environment.

[0100] Overall, the addition of TiO2 not only improves the anti-aging ability of the mulch film but also extends the service life of the mulch film to a certain extent. Different from conventional antioxidants, TiO2 has photocatalytic properties and can also degrade organic pollutants under certain conditions, which has additional ecological value in the agricultural environment.

[0101] Experiment 2: Antibacterial performance test This experiment aims to test the performance of different plastic film samples in inhibiting the growth of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), and to verify the contribution of silver nanoparticles (AgNPs) and tea tree oil extract to the antibacterial effect. The experiment was carried out by inoculating the bacterial culture solution onto the surface of the plastic film, observing the antibacterial effect, and measuring the size of the inhibition zone and the colony growth. Example 2 (containing AgNPs and tea tree oil) was compared with Comparative Example 2 (without AgNPs), and the traditional PE plastic film was used as a control.

[0102] Experimental procedures Sample preparation: Cut plastic film specimens of 5 cm × 5 cm, numbered A (Example 2), B (Comparative Example 2), and C (Comparative Example 5).

[0103] Disinfect the surface of the samples to avoid external contamination.

[0104] Bacterial inoculation: Prepare E. coli and B. subtilis bacterial solutions (1×10 6 CFU / mL). Under sterile conditions, use a pipette to drop 100 μL of the bacterial solution onto the surface of each plastic film specimen.

[0105] Use sterile filter paper to absorb the excess liquid to ensure that the bacterial solution completely covers the surface of the plastic film.

[0106] Cultivation and observation: Place the inoculated plastic film samples in an incubator at 37 °C for 24 hours.

[0107] Observe the samples every 6 hours, record the diameter of the inhibition zone (in millimeters), and take images of the surface of the samples.

[0108] Result measurement: Record the changes in the number of colonies and the diameter of the inhibition zone at each observation.

[0109] At the end of the experiment, use an electronic balance to weigh the mass of bacteria (CFU) that may adhere to the surface of the plastic film to further calculate the antibacterial effect.

[0110] Note: The diameter of the inhibition zone is the inhibition range of E. coli and B. subtilis, and the number of colonies (CFU) represents the number of bacteria adhering to the surface of each plastic film specimen.

[0111] From the experimental data, Example 2 showed obvious advantages in antibacterial effects, especially in the inhibitory effect on Escherichia coli (E. coli). Silver nanoparticles (AgNPs) interact with bacterial cell walls and membranes by releasing silver ions (Ag+), destroying the cell structure and ultimately leading to bacterial death. In addition, the antibacterial components of tea tree oil extract can further enhance this effect, especially at high concentrations, significantly enhancing the inhibitory effect on bacteria. Therefore, the plastic film containing AgNPs and tea tree oil can effectively reduce bacterial growth and reduce the spread of crop diseases when in contact with bacteria.

[0112] In contrast, for the plastic film sample of Comparative Example 2 (without AgNPs), although it still had a certain antibacterial effect, the effect was far less than that of Example 2. As the experimental time passed, the increase in the diameter of the antibacterial circle was small, and the number of colonies was not significantly inhibited, which proved the important role of silver nanoparticles in antibacterial. The traditional PE plastic film (Comparative Example 5) had almost no antibacterial effect, and the number of colonies increased continuously over time, indicating that it did not have antibacterial properties.

[0113] Experiment 3: Water retention performance test This experiment aimed to study the effects of different plastic film materials on soil water evaporation and evaluate the contribution of nano-silica (SiO2) and biobased polymers to soil water retention performance. The experiment analyzed the differences in water retention capacity by measuring the water loss of soil samples covered with different plastic films in a constant temperature environment.

[0114] Experimental procedure Soil preparation: Take the same mass (500 g) of farmland soil and evenly fill it into a plastic container with a diameter of 15 cm and a height of 10 cm.

[0115] Ensure that the soil humidity is uniform, and the initial water content is set at 25%.

[0116] Plastic film covering: Select three plastic film materials: A (Example 3, containing SiO2 and biobased polymer), B (Comparative Example 3, traditional PE plastic film), C (uncovered control group).

[0117] Completely cover the surface of the container with the plastic film, leaving only a ventilation hole with a diameter of 1 cm.

[0118] Constant temperature incubation: Place it in a constant temperature incubator at 30 °C to simulate a high-temperature evaporation environment.

[0119] Weigh the total mass of the container every 24 hours and calculate the soil water loss.

[0120] Data recording: Record the water evaporation at each time point and calculate the water retention rate.

[0121] Continuously observe for 10 days and analyze the water retention effects of different plastic films.

[0122] Note: Water retention rate = (Initial water - Water loss) / Initial water × 100%.

[0123] The retention of water is closely related to the microstructure of the material. Experimental data shows that the plastic film in Example 3 performs best in reducing soil water evaporation, and its water retention rate is always higher than that of Comparative Example 3 and the non-covered control group. This is mainly attributed to the water retention characteristics of SiO2 nanoparticles, which form a microporous structure on the surface of the plastic film, capable of both reducing the water evaporation rate and regulating soil humidity to a certain extent. In contrast, although the traditional PE plastic film can reduce evaporation, due to its strong hydrophobicity, it cannot effectively adsorb water, resulting in a relatively low water retention rate.

[0124] Interestingly, in the later stage of the experiment, the differences in the water loss curves among the three treatments are more obvious. The soil water in the non-covered group drops extremely fast, with nearly 60% water loss within 10 days, and the bare soil is almost dry. Although the water loss of the PE plastic film slows down, it is still significant, indicating that its barrier effect is limited. On the other hand, the bio-based polymer used in Example 3 makes the water inside the soil more difficult to evaporate by enhancing water cohesion, thereby improving the long-term water retention ability. This shows that the introduction of the composite nano material not only optimizes the air permeability of the plastic film but also further enhances its function of regulating water.

[0125] Simple physical covering is far from enough, and the microscopic mechanism is the key. SiO2 particles not only reduce the water diffusion rate but also enhance the affinity between the plastic film and the soil interface, reducing the possibility of water escaping along the interface. At the same time, the porous structure of the bio-based polymer is similar to a sponge, which can release water when the environmental humidity decreases, thus stabilizing the soil humidity to a certain extent. This dual mechanism enables Example 3 to have stronger water retention ability and is more suitable for agricultural applications in arid or semi-arid regions compared with traditional materials.

[0126] Experiment 4: Temperature regulation performance test This experiment mainly tests the temperature regulation ability of different plastic film materials in the agricultural planting environment and analyzes their effects on soil temperature. The roles of nano-aluminum oxide (Al2O3) and infrared reflective coatings are mainly evaluated. By recording the soil temperature changes under different plastic film coverings, verify their heat preservation or cooling effects under different times and environmental conditions.

[0127] Experimental procedures Test field preparation: Fields in the same area were selected and divided into three test areas, which were numbered A (Example 4, containing Al2O3+infrared reflective coating), B (Comparative Example 4, traditional black PE mulch), and C (uncovered control group).

[0128] The soil in the field is tilled evenly to ensure consistent soil moisture.

[0129] Mulching: Lay the corresponding ground film in test areas A and B, ensuring that the edges are compacted to prevent it from being blown away by wind.

[0130] The C test area remained bare without any covering treatment.

[0131] Temperature monitoring: Temperature sensors were buried at depths of 5cm, 10cm, and 15cm in each field to record soil temperature in real time.

[0132] The measurement times are set at 6:00, 12:00, 18:00, and 24:00 every day to cover the temperature fluctuations of the day.

[0133] Data recording and analysis: Observe for 10 days, record the trend of soil temperature changes, and calculate the daily temperature difference (maximum temperature - minimum temperature).

[0134] Combined with external meteorological data, the effect of ground film on regulating soil temperature is analyzed.

[0135] Note: During the experiment, the ambient temperature fluctuated between 16.5°C and 35.2°C.

[0136] From the data, Example 4 shows excellent temperature control ability, especially during the high temperature period during the day, its cooling effect is particularly obvious. Nano-alumina (Al2O3) has efficient heat reflection characteristics, which can reduce the penetration of solar radiation into the deep layer of the soil. At the same time, the infrared reflection coating further enhances this effect, making the soil temperature in test area A lower than that in test areas B and C. The temperature fluctuation of the exposed soil is the largest, and the highest temperature at noon even reaches 33.8℃, while the highest temperature in test area A is controlled at around 24.6℃, which significantly reduces the risk of soil heat stress.

[0137] On the other hand, the traditional PE mulch heats up quickly during the day, but cools down slowly at night, resulting in a large temperature difference between day and night. This situation may be unfavorable for some crops, especially in an environment with drastic temperature fluctuations, which may affect the root growth and water metabolism of crops. In contrast, the material used in Example 4 effectively buffered the temperature difference between day and night and maintained a relatively stable soil temperature, which is more friendly to the growth cycle of crops.

[0138] Ultimately, the key to temperature regulation lies not in a single covering material, but in the microstructure and optical properties of the material. The high reflectivity of Al2O3 particles can effectively reduce the absorption of short-wave radiation, while the infrared reflective coating reduces heat loss at night, maintaining a relatively stable thermal environment. This two-way regulation mechanism keeps the soil in Test Area A from overheating during the day and from getting too cold at night, creating a more suitable growth environment for crops.

[0139] Experiment 5: Wind Resistance Performance Test This experiment aims to evaluate the performance of different plastic films in terms of wind resistance, especially their durability in strong wind weather. By simulating strong wind conditions, the damage and structural stability of different plastic film materials under wind pressure are tested, and their durability at high wind speeds is analyzed. In the experiment, a composite plastic film containing reinforcing fibers (Example 5) is compared with a traditional PE plastic film, and a non-covered group is added for control.

[0140] Experimental Procedures Preparation of Plastic Film Samples: Select plastic film samples of the same specification (30 cm × 30 cm), numbered A (Example 5, composite plastic film containing reinforcing fibers), B (Comparative Example 5, traditional PE plastic film), and C (non-covered control group).

[0141] Inspect the surface of the samples to ensure no obvious damage.

[0142] Wind Pressure Simulation: Fix the samples in the wind speed simulation device to simulate the impact of different wind speeds on the plastic films. Set the wind speed range from 0 to 60 m / s to simulate different intensities of wind pressure environments.

[0143] Each experiment lasts for 30 minutes, and record the wind speed, wind pressure, and the damage situation of the samples.

[0144] Compression Resistance Test: After the wind speed reaches the preset value, record the deformation situation of the samples at each time point. Analyze their wind pressure resistance by observing the rupture, wrinkling of the samples, and the expansion of the damaged areas.

[0145] Data Recording and Analysis: After each experiment, measure the damaged area of the plastic film and record the relationship between the wind pressure and the damaged area. Repeat the experiment 3 times at each wind speed to ensure the reliability of the data.

[0146] Note: The damaged area is the size of the area where the plastic film ruptures after being affected by wind pressure, and the degree of deformation is the warping or bending degree of the plastic film under the action of wind pressure.

[0147] Judging from the experimental data, Example 5 has excellent wind pressure resistance. The introduction of the reinforced fiber composite material enables the plastic film to exhibit strong deformation resistance and breakage resistance when facing relatively high wind speeds. When the wind speed is 60 m / s, the breakage area of Example 5 is only 18.7 cm², which is significantly smaller than that of the traditional PE plastic film (32.4 cm²). This indicates that the fiber-reinforced material effectively improves the tensile and tear resistance of the plastic film, thereby reducing the breakage risk at high wind speeds. In contrast, although the traditional PE plastic film performs well at low wind speeds, as the wind speed increases, the breakage area increases rapidly, indicating its limited wind pressure resistance.

[0148] In the case of no covering, the plastic film is not protected, and the higher the wind speed, the greater the influence of wind pressure on the soil surface. The bare soil is easily damaged in strong wind weather, resulting in soil erosion and surface drying. In the experiment, obvious damage occurred in the non-covering group when the wind speed reached 50 m / s, and even surface cracks and soil erosion occurred, further verifying the important role of the plastic film in protecting the soil.

[0149] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An eco-friendly microbial degradable mulch film, characterized in that: Includes the following mass percentages: 50%-65% polylactic acid; 15%-25% lignocellulose; 5%-10% glycerol; 0.5%-2% nano titanium dioxide; 0.1%-0.5% silver nanoparticles; 0.5%-2% tea tree oil extract; 15%-20% carboxymethyl cellulose; 13%-15% plant growth regulators; 5%-10% additives.

2. The eco-friendly microbial degradable mulch film according to claim 1, characterized in that: The auxiliary agent includes one or more of an antioxidant, a plasticizer and a light stabilizer, and the plant growth regulator includes one or more of a seaweed extract, indoleacetic acid or oleanolic acid.

3. A method for preparing an eco-friendly microbial degradable mulch film, according to any one of claims 1-2, characterized in that: The following steps are involved: S1, dissolving polylactic acid, lignocellulose and glycerol in a solvent to obtain a uniform solution; S2, adding nano titanium dioxide, silver nanoparticles, tea tree oil extract and carboxymethyl cellulose to the solution, and stirring evenly to obtain a composite solution; S3, uniformly coating or impregnating the composite solution on the polylactic acid film to form a composite film; S4, drying the composite film; S5. The dried composite film is irradiated with ultraviolet light to obtain a ground film.

4. The method for preparing an eco-friendly microbial degradable mulch film according to claim 3, characterized in that: In the step S1, the solvent includes chloroform or dichloromethane, and the amount thereof is 10%-20% of the total mass of the polylactic acid and the lignocellulose.

5. The method for preparing an eco-friendly microbial degradable mulch film according to claim 3, characterized in that: In the step S3, the composite solution is treated with ultrasound during the stirring process, the treatment frequency is 20 kHz to 40 kHz, and the treatment time is 5 minutes to 10 minutes.

6. The method for preparing an eco-friendly microbial degradable mulch film according to claim 3, characterized in that: The coating or immersion time in the step S3 is 30 minutes to 60 hours to form a uniform coating.

7. The method for preparing an eco-friendly microbial degradable mulch film according to claim 3, characterized in that: The steps in step S4 include: Place the coated or impregnated film in a constant temperature and humidity drying room, the drying temperature is 40℃ to 60℃, the humidity is controlled between 40%-60%, and the drying time is 4 hours to 8 hours.

8. The method for preparing an eco-friendly microbial degradable mulch film according to claim 3, characterized in that: The wavelength of the ultraviolet irradiation in step S5 is 315-400nm, the intensity of the ultraviolet irradiation is 10mW / cm² to 50mW / cm², and the irradiation time is 30 minutes.

9. The method for preparing an eco-friendly microbial degradable mulch film according to claim 3, characterized in that: The thickness of the composite film is 20 μm to 100 μm, and the thickness uniformity error of the film does not exceed 5%.

10. The method for preparing an eco-friendly microbial degradable mulch film according to claim 3, characterized in that: The addition ratio of polylactic acid, lignocellulose and glycerol in S1 is 4:1:1 to 6:2:1, and the addition ratio of nano-titanium dioxide, silver nanoparticles, tea tree oil extract and carboxymethyl cellulose in S2 is 3:0.5:2:4 to 5:1:3:6.

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