Controllable degradation bio-mulch with herbicide and insecticide functions and preparation method thereof

Abstract

The present application relates to the technical field of agricultural biodegradable materials, in particular to a controllable degradable biological mulch with weed control and insect prevention function and a preparation method thereof, the mulch comprises the following components in mass percentage: biodegradable matrix material 50-75%, natural plant source weed control and insect prevention master batch 5-25%, controllable degradable modified master batch 1-15% and functional additives 0.1-10%. The master batch is a natural ingredient such as sophora flavescens extract and azadirachtin processed into 100-400 mesh fine powder by a fine grinder to achieve green and safe insect prevention and weed control. The controllable degradable modified master batch is a composite of copolymer of PBS, PCL, PLA and PBAT and modified biomass filler. The beneficial effect is that the mulch is made by blending, extrusion, casting or blow molding, the degradation period can be accurately controlled within 30-120 days, and the mulch has excellent weed control and insect prevention effect. The present application solves the technical problems of serious pollution of traditional mulch, uncontrollable degradation period and dependence on chemical pesticides, and realizes the green and sustainable development of agriculture.

Description

Technical Field

[0001] This invention relates to the field of agricultural biodegradable materials technology, specifically to a controllable biodegradable mulch film with weed control and insect repellent functions and its preparation method. Background Technology

[0002] With the development of agricultural modernization, plastic film mulching technology has become an important means to ensure increased crop yields and income. However, traditional polyethylene (PE) mulch film is difficult to degrade under natural conditions, and long-term use leads to the accumulation of large amounts of residue in the soil, forming serious "white pollution," damaging soil structure, and affecting crop root growth and water and nutrient absorption. To solve this problem, biodegradable mulch films, represented by polylactic acid (PLA) and polybutylene terephthalate (PBAT), have emerged and are gradually being promoted and applied.

[0003] However, existing biodegradable mulch films still have two major drawbacks in practical applications: First, the degradation cycle is uncontrollable. If the mulch film degrades too early during the crop seedling stage, it will lose its heat and moisture retention functions; conversely, if it degrades too late after the crop growth period, it may affect root respiration and cause later pollution. Second, it lacks biological control functions. Existing biodegradable mulch films cannot effectively replace chemical pesticides for weed and pest control, resulting in the continued need for large amounts of herbicides and insecticides during the planting process. This not only increases production costs but also leads to problems such as pesticide residues and increased pesticide resistance in pests and diseases, making it difficult to meet the requirements for green and safe planting of high-value-added cash crops such as vegetables and medicinal herbs.

[0004] Therefore, developing a biofilm with a precisely controllable degradation cycle and natural weeding and pest control functions is of great significance for promoting the green and sustainable development of agriculture. Summary of the Invention

[0005] To overcome the technical deficiencies in the prior art and effectively solve the technical problems in the background art, the present invention provides the following technical solution: A controllable biodegradable mulch film with weed control and insect repellent functions comprises the following components by weight percentage: Biodegradable matrix materials: 50%-75%; Natural plant-derived herbicide and insect repellent masterbatch: 5%-25%; Controlled degradation modified masterbatch: 1%-15%; Functional additives: 0.1%-10%.

[0006] As a preferred embodiment of the present invention, the biodegradable matrix material is selected from one of polylactic acid (PLA), polybutylene terephthalate (PBAT), polycaprolactone (PCL), polymethyl ethylene carbonate (PPC), and polypropylene carbonate (PPC-P).

[0007] As a preferred embodiment of the present invention, the biodegradable matrix material is selected from a composition consisting of at least two of polylactic acid (PLA), polybutylene terephthalate (PBAT), polycaprolactone (PCL), polymethyl ethylene carbonate (PPC), and polypropylene carbonate-phthalate (PPC-P).

[0008] As a preferred technical solution of the present invention, the natural plant-derived herbicide and insect repellent masterbatch is made of the following components in weight percentage: 1%-20% Sophora flavescens extract, 1%-10% azadirachtin, 1%-10% Artemisia argyi powder, 1%-20% diatomaceous earth, and the balance being carrier resin; the Sophora flavescens extract, azadirachtin, and Artemisia argyi powder are first processed into fine powder of 100-400 mesh by a fine grinding machine, and then mixed and granulated with the carrier resin at ≤80℃.

[0009] As a preferred embodiment of the present invention, the controllable degradation modified masterbatch is a composite of copolymers or blends of polybutylene succinate (PBS), polycaprolactone (PCL), polylactic acid (PLA), and polybutylene terephthalate adipate (PBAT) with modified biomass fillers.

[0010] As a preferred embodiment of the present invention, the functional additives include compatibilizers, antioxidants, light stabilizers, and hydrophobic modifiers.

[0011] As a preferred technical solution of the present invention, the degradation cycle of the mulch film is adjusted by regulating the amount of controllable degradation modified masterbatch added, so as to achieve phased complete degradation from 30 to 120 days after sowing.

[0012] A method for preparing a controllable degradable biofilm with weed control and insect repellent functions includes the following steps: (1) Masterbatch preparation: Sophora flavescens extract, azadirachtin, and Artemisia argyi powder are used as natural plant-derived insect repellent liquids and are subjected to surface densification treatment to obtain fine powders; then the fine powders are extruded and granulated with low melting point carrier resin (PCL or PBS) at ≤80℃ using a low temperature twin-screw extruder to obtain natural plant-derived herbicidal and insect repellent masterbatch with a particle size of 2-3mm. (2) Pre-drying: Vacuum dry the biodegradable matrix material, controllable degradation modified masterbatch and functional additives at 60-80℃ for 4-6 hours; (3) Blending extrusion: Mix all components evenly according to the formula, feed them into the extruder, and perform melt extrusion using a temperature control gradient of 140℃-170℃; (4) Forming and winding: The film is made into a mulch film with a thickness of 0.01mm-0.05mm through a cast film production line or blown film production line, and then corona treatment is performed to make the finished mulch film.

[0013] As a preferred technical solution of the present invention, the melt temperature of the extrusion process in step (3) is strictly controlled at 150℃-180℃, and when the masterbatch is mixed with the matrix material in step (3), it is added in the rear section of the extruder by side feeding to reduce heat loss.

[0014] A method for applying a controllable degradable biofilm with weed control and insect repellent functions to the cultivation of vegetables, medicinal herbs, and cash crops, comprising the following steps: (1) Land preparation and fertilization: conventional tillage and ridging; (2) Film laying and sowing: Lay the mulch film and use precision sowing by punching holes or drip irrigation under the film for sowing; (3) Management during the growing season: No additional herbicide spraying is required after emergence. The mulch film inhibits weed growth by releasing plant-derived volatile substances, while continuously releasing insect-repellent ingredients. (4) Natural degradation: When crops reach the critical growth period, the plastic film naturally breaks down and degrades.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Green and safe, pesticide alternative: It uses natural plant-derived ingredients such as matrine and azadirachtin to achieve green and safe pest and weed control. It is non-toxic, harmless, and free of chemical pesticide residues, and especially meets the food safety standards for high-value-added crops such as vegetables and Chinese medicinal herbs.

[0016] 2. Precise and controllable, with strong adaptability: Through the composite regulation of copolymers of PBS, PCL, PLA, and PBAT with modified biomass fillers, the degradation rate of the mulch film can be precisely set according to the crop growth cycle (30-120 days), solving the pain points of "early degradation failure" and "late degradation pollution" of traditional degradable mulch films.

[0017] 3. Increased production and efficiency, ecological cycle: After the plastic film degrades, it returns to the soil as organic matter, increasing soil fertility; the weeding and pest control functions greatly reduce the input of labor and pesticides, and the overall economic benefits are significantly improved.

[0018] The functions of each component in this invention are as follows: The biodegradable matrix material provides the basic mechanical strength and toughness of the mulch film.

[0019] The natural plant-derived herbicide and insect repellent masterbatch is the core functional component, providing long-lasting active ingredients for herbicide and insect repellent.

[0020] The controllable degradation modified masterbatch is a key component for regulating the degradation rate.

[0021] The functional additives are used to improve component compatibility, processing performance, and weather resistance. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described more clearly and completely below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] This invention provides a technical solution: a controllable degradable biological mulch film with weed control and insect prevention functions.

[0024] A method for preparing a controllable biodegradable mulch film with weed control and insect repellency functions includes masterbatch preparation, pre-drying, co-extrusion, molding and winding, and functional finishing steps.

[0025] Example 1: Rapidly degradable mulch film suitable for fast-growing leafy vegetables (such as lettuce and spinach) This embodiment provides a controllable biodegradable mulch film with weed control and insect repellent functions, the formulation of which is as follows: PLA (2002D): 60%; PBAT: 15%; Natural weed and insect repellent masterbatch: 20% (containing 10% matrine, 5% azadirachtin, and 5% artemisia powder); Controlled-degradability modified masterbatch (PBS, PCL, PLA, PBAT copolymer + modified starch): 5%; Functional additives (antioxidants, compatibilizers, etc.): 5%.

[0026] Preparation method: (1) Sophora flavescens extract, azadirachtin and gum arabic are emulsified, spray-dried to form microcapsules, ensuring an encapsulation rate of ≥80%, and then mixed with PBAT slices for granulation to obtain natural plant-derived herbicidal and insect-repellent masterbatch. (2) The PLA, PBAT, controllable degradation modified masterbatch and functional additives were vacuum dried at 70°C for 5 hours; (3) Mix all components evenly according to the ratio and feed them into a twin-screw extruder. Use the temperature control gradient: barrel 1: 140℃, barrel 2: 150℃, barrel 3: 160℃, connector: 165℃, die head: 168℃ for melt extrusion. The melt temperature is controlled within 170℃. (4) A 0.015mm thick mulch film is produced by casting film production line and then corona treatment is performed to produce the finished mulch film.

[0027] Performance testing and application results: Local plastic film was used for spring lettuce cultivation, with drip irrigation under the film for sowing. The experimental results showed: Degradation performance: The plastic film degrades completely 45-60 days after sowing, which is highly compatible with the growth cycle of lettuce.

[0028] Weed control effect: Within 3 days after mulching, the germination rate of weeds in the field decreased by 60%, and no herbicide spraying was required throughout the entire growing season.

[0029] Insect control effect: It has a repellency rate of 75% against common pests such as aphids and diamondback moths, reduces the incidence of pests by 80%, and reduces the amount of chemical pesticides used by 90%.

[0030] Yield comparison: Compared with ordinary PLA / PBAT mulch film, lettuce yield per acre increased by 12.3%.

[0031] Example 2: Long-lasting heat-insulating mulch film suitable for rhizomes and medicinal herbs (such as Astragalus membranaceus) This embodiment provides a controllable biodegradable mulch film with weed control and insect repellent functions, the formulation of which is as follows: PLA (4032D): 50%; PBAT: 20%; Natural weed killer and insect repellent masterbatch: 15%; Controlled-degradability modified masterbatch (high PCL content PBS, PCL, PLA, PBAT copolymer + modified straw powder): 15%; Functional additives (compensators, antioxidants, light stabilizers): 5%.

[0032] The preparation method is the same as in Example 1, except that the proportion of controllable degradable modified masterbatch and process parameters are adjusted, and the die head temperature is controlled at 165℃.

[0033] Performance testing and application results: When local mulch was used for Astragalus cultivation, the experimental results showed that: Degradability: The mulch film completely degrades 90-120 days after sowing, meeting the needs of Astragalus membranaceus for heat preservation and moisture retention in the early stage and aeration and root promotion in the later stage.

[0034] Weed control effect: Throughout the entire growth period, the biomass of weeds was reduced by 70.5% compared with the control, effectively reducing nutrient competition.

[0035] Insect control effect: It has a repellency rate of 82% against underground pests such as cutworms and grubs, and reduces the incidence of root rot by 35%.

[0036] Increased yield: The yield of Astragalus membranaceus per mu increased by 18.6%, and no pesticide residues were detected in the medicinal material, which meets the standards for green Chinese medicinal materials.

[0037] Example 3: Medium-efficiency mulch film suitable for solanaceous vegetables (such as tomatoes) This embodiment provides a controllable biodegradable mulch film with weed control and insect repellent functions, the formulation of which is as follows: PBAT: 55%; PLA: 10%; Natural weed killer and insect repellent masterbatch: 18%; Controlled-degradability modified masterbatch (PBS, PCL, PLA, PBAT copolymer + modified biochar): 12%; Functional additives: 5%.

[0038] The preparation method is the same as in Example 1.

[0039] Performance testing and application results: When local plastic film was used for spring tomato planting, the experimental results showed that: Degradation performance: The mulch film completely degrades 70-85 days after sowing, covering the entire growth period of tomatoes.

[0040] Weed control effect: Weed coverage was reduced by 65.3%, saving about 150 yuan / mu in manual weeding costs.

[0041] Insect control effect: It achieves a 78% control effect on whiteflies and aphids, and reduces the amount of chemical pesticides used by 90%.

[0042] Yield and quality: Tomato yield per mu increased by 15.2%, soluble solids content increased by 8%, and marketable fruit rate increased by 12%.

[0043] Comparative Example 1: Traditional PE Mulch Film The formula is 100% polyethylene with a thickness of 0.01 mm.

[0044] The test results showed that the degradation cycle was >360 days, resulting in serious soil residues; it had no weeding or insect control function and required the use of large amounts of chemical pesticides; and it required manual recycling after crop harvest, which was costly.

[0045] Comparative Example 2: Commercially available ordinary PLA / PBAT biodegradable mulch film The formula consists of 60% PLA and 40% PBAT, with no functional masterbatch or degradation control components.

[0046] The test results showed that the degradation cycle was uncontrollable, and large-scale cracking occurred 30-40 days after sowing, resulting in the loss of heat preservation and moisture retention effects; it also had no weed control or insect prevention function, and weeds and pests became serious.

[0047] Performance Comparison Summary To more intuitively demonstrate the technical advantages of the present invention, the key performance indicators of the above embodiments and comparative examples are summarized and compared, and the results are shown in Table 1.

[0048] Table 1 Comparison of the performance of different plastic film mulches

[0049] As shown in Table 1, the mulch films of Examples 1-3 of this invention not only allow for precise control of their degradation cycle according to crop needs, but also exhibit significant advantages in weed control, pest control, and yield enhancement. Compared to traditional PE mulch films and commercially available ordinary biodegradable mulch films, the mulch films of this invention achieve complete biodegradation while significantly reducing the use of chemical pesticides, improving crop yield and quality, and demonstrating superior overall performance.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A controllable degradable biofilm with weed control and insect repellent functions, characterized in that: Includes the following components by mass percentage: Biodegradable matrix materials: 50%-75%; Natural plant-derived herbicide and insect repellent masterbatch: 5%-25%; Controlled degradation modified masterbatch: 1%-15%; Functional additives: 0.1%-10%.

2. The controllable degradable biofilm with weed control and insect repellent functions according to claim 1, characterized in that: The biodegradable matrix material is selected from one of polylactic acid, polybutylene terephthalate, polycaprolactone, polymethyl ethylene carbonate, and polypropylene carbonate.

3. The controllable degradable biofilm with weed control and insect repellent functions according to claim 1, characterized in that: The biodegradable matrix material is selected from a composition consisting of at least two of polylactic acid, polybutylene terephthalate, polycaprolactone, polymethyl ethylene carbonate, and polypropylene carbonate.

4. The controllable degradable biofilm with weed control and insect repellent functions according to claim 1, characterized in that: The natural plant-derived herbicide and insect repellent masterbatch is made from the following components by weight percentage: 1%-20% Sophora flavescens extract, 1%-10% azadirachtin, 1%-10% Artemisia argyi powder, 1%-20% diatomaceous earth, with the remainder being carrier resin. The Sophora flavescens extract, azadirachtin, and Artemisia argyi powder are first processed into fine powder of 100-400 mesh by a fine grinding machine, and then mixed and granulated with the carrier resin at ≤80℃.

5. The controllable degradable biofilm with weed control and insect repellent functions according to claim 1, characterized in that: The controllable degradation modified masterbatch is a composite of copolymers or blends of polybutylene succinate, polycaprolactone, polylactic acid, and polybutylene terephthalate-adipate with modified biomass fillers.

6. The controllable degradable biofilm with weed control and insect repellent functions according to claim 1, characterized in that: The functional additives include compatibilizers, antioxidants, light stabilizers, and hydrophobic modifiers.

7. The controllable degradable biofilm with weed control and insect repellent functions according to claim 1, characterized in that: The degradation cycle of the mulch film can be adjusted by regulating the amount of controllable degradation modified masterbatch added, achieving phased complete degradation from 30 to 120 days after sowing.

8. The method for preparing a controllable degradable biofilm with weed control and insect repellent functions according to any one of claims 1-7, characterized in that: Includes the following steps: S1: Masterbatch preparation: Sophora flavescens extract, azadirachtin, and Artemisia argyi powder are used as natural plant-derived insect repellent liquids, and then surface densification treatment is carried out to obtain fine powder; the fine powder is then extruded and granulated with low melting point carrier resin at ≤80℃ using a low temperature twin-screw extruder to obtain natural plant-derived herbicidal and insect repellent masterbatch with a particle size of 2-3mm. S2: Pre-drying: Vacuum dry the biodegradable matrix material, controllable degradation modified masterbatch and functional additives at 60-80℃ for 4-6 hours; S3: Blending extrusion: Mix all components evenly according to the formula, feed them into the extruder, and perform melt extrusion using a temperature control gradient of 140℃-170℃; S4: Forming and winding: The film is made into a mulch film with a thickness of 0.01mm-0.05mm through a cast film production line or blown film production line, and then corona treatment is performed to make the finished mulch film.

9. The method for preparing a controllable degradable biofilm with weed control and insect repellent functions according to claim 8, characterized in that: In step S3, the melt temperature of the extrusion process is strictly controlled between 150℃ and 180℃. When the masterbatch is mixed with the matrix material in step S3, it is added at the rear of the extruder using a side-feeding method to reduce heat loss.

10. The application method of the controllable degradable biofilm with weed control and insect repellency function according to any one of claims 1-7, characterized in that: This method is applied to the cultivation of vegetables, medicinal herbs, and cash crops. The specific steps are as follows: S1: Land preparation and fertilization: conventional tillage and ridging; S2: Film-laying and sowing: Lay the aforementioned film and use precision sowing with perforation or drip irrigation under the film for sowing; S3: Growth period management: No additional herbicide spraying is required after emergence. The mulch film inhibits weed growth by releasing plant-derived volatile substances, while continuously releasing insect repellent ingredients. S4: Natural degradation: When crops reach the critical growth stage, the plastic film naturally breaks down and degrades.

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