Water-soluble film of agricultural spraying oil preparation as well as preparation method and application of water-soluble film

Abstract

The invention discloses a water-soluble film of an agricultural spraying oil preparation as well as a preparation method and application of the water-soluble film, and belongs to the technical field of degradable film materials. The water-soluble film is prepared by taking modified corn starch as a main raw material and matching with a plasticizer, an emulsifier, a cross-linking agent, a filler and a cosolvent through an optimized formula and a preparation process. The film has the advantages of excellent mechanical properties, strong hydrophilicity, uniform film formation, high transparency, complete degradability and no pollution to the environment. When the water-soluble film and the liquid medicine are dissolved in water, the compatibility is good, the problem of environmental pollution caused by traditional plastic packaging is avoided, the repellent effect of the liquid medicine is enhanced, and the pesticide application efficiency is improved. The packaging mode is convenient to operate, does not need to be measured, ensures accurate dosage, and is low in cost. Through the innovative preparation method, the storage stability and the use performance of the water-soluble film are remarkably improved, and an efficient, environment-friendly and economic solution is provided for green development of agriculture.

Description

Technical Field

[0001] The invention belongs to the technical field of degradable film materials, and in particular relates to a water-soluble film of an agricultural spray oil preparation and a preparation method and application thereof. Background Art

[0002] With the development of modern agriculture, the use of pesticides has played an important role in improving crop yield and quality. However, there are many problems with traditional pesticide packaging and application methods, especially environmental pollution and resource waste. In recent years, the research on degradable materials and green packaging technology has gradually become an important direction to solve these problems. Among them, water-soluble film, as a new type of environmentally friendly material, has attracted attention due to its excellent performance and wide application potential.

[0003] At present, pesticide packaging mainly adopts plastic bottles or plastic bags. These plastic packaging has the characteristics of strong stability and non-degradability, but it also brings the following problems:

[0004] -Environmental pollution: Plastic packaging waste is difficult to degrade naturally. If it remains in the soil for a long time, it will destroy the soil structure, affect the growth of crop roots, and pollute water bodies and ecosystems.

[0005] - Waste of resources: There is often liquid medicine residue on the inner wall of plastic bottles, which reduces the efficiency of use and increases the cost of waste disposal.

[0006] - Inconvenient operation: Traditional large-bottle pesticides need to be measured and diluted before use, which is complicated and error-prone, and is not conducive to precise application.

[0007] According to statistics, the environmental pollution caused by improper disposal of pesticide packaging waste is becoming increasingly serious in my country every year, and the production and recycling costs of plastic packaging are also rising. These problems urgently need to be solved by developing new environmentally friendly materials and improving packaging forms.

[0008] In order to reduce the environmental burden brought by traditional plastics, degradable materials have gradually become a research hotspot. Degradable materials are mainly divided into the following categories:

[0009] -Photodegradable materials: decompose under light through photosensitizers, but their degradation process is limited by environmental conditions and it is difficult to completely solve the pollution problem.

[0010] -Biodegradable materials: Based on natural polymers (such as starch and cellulose), they can be decomposed into carbon dioxide and water by microorganisms and are one of the most promising environmentally friendly materials.

[0011] -Dual-degradable materials: Combining photodegradation and biodegradation technologies improves degradation efficiency, but the cost is higher.

[0012] Among them, biodegradable materials with starch as the main component have attracted much attention due to their wide sources, low prices and excellent performance. For example, films prepared by blending starch with polyvinyl alcohol have been used in agriculture to a certain extent, but their mechanical properties and hydrophilicity still need to be further optimized.

[0013] Water-soluble film is a new type of green packaging material made of polyvinyl alcohol or modified starch. It has the following characteristics:

[0014] -Completely degradable: After dissolving in water, it can be further decomposed into carbon dioxide and water by microorganisms, without any pollution to the environment.

[0015] -Excellent performance: good transparency, oil resistance, gas barrier properties and high mechanical strength.

[0016] -Wide application scenarios: It has been used in detergent packaging bags, agricultural seed bags, herbicide inner packaging and other fields.

[0017] In recent years, the research on water-soluble films at home and abroad has focused on improving its production process and optimizing its performance. For example, the film is produced by casting or extrusion blowing, and its flexibility and hydrophilicity are improved by adding plasticizers, cross-linking agents, etc. However, these processes still have certain technical difficulties, such as high energy consumption and high cost.

[0018] Agricultural spray oil preparation is a new type of pesticide preparation with plant-derived glyceride as the main ingredient. It has the following characteristics:

[0019] -It has a physical contact killing effect on pests and can also prevent them from laying eggs and feeding;

[0020] -High viscosity makes it easy to adhere to the container wall during measuring and spraying, affecting the efficiency of use;

[0021] -The traditional large bottle format is not conducive to accurate application of the drug and also increases the complexity of the operation.

[0022] Therefore, in order to meet the needs of agricultural production for environmental protection, high efficiency and convenience, it is necessary to develop a new packaging form that is compatible with spray oil preparations and environmentally friendly.

[0023] Using water-soluble film for agricultural spray oil packaging can not only solve the environmental pollution problem caused by traditional plastic packaging, but also significantly improve the efficiency of pesticide application. Specific advantages include:

[0024] - Environmental protection: The water-soluble film and the liquid medicine can be directly dissolved in water, without the need for recycling and treatment, and will not pollute the environment;

[0025] -Easy to operate: eliminating the need for measuring steps and achieving precise application of pesticides;

[0026] - Enhanced efficacy: Experiments have shown that water-soluble film materials and plant-derived glycerides have good compatibility in water and can further enhance the repellent effect on pests and mites;

[0027] -Cost advantage: Compared with traditional plastic bottle packaging, water-soluble film has lower cost and reduces the waste of liquid medicine caused by residue.

[0028] In summary, under the current background of green agricultural development, the development of a new agricultural spray oil preparation packaging form based on degradable water-soluble film not only meets the requirements of national environmental protection policies, but also effectively solves the problems existing in traditional pesticide packaging, and provides a more environmentally friendly, efficient and economical solution for agricultural production. This technology will promote the widespread application of degradable film materials in the agricultural field, and at the same time promote the transformation of agricultural production methods towards green and intelligent. Summary of the invention

[0029] 1. Problems to be solved

[0030] In view of the problems existing in the preparation process of the existing water-soluble film, the present invention aims to solve the following technical problems: Insufficient mechanical properties: The tensile strength and elongation at break of ordinary water-soluble films are low, and they are easily damaged during use, which makes it difficult to meet the packaging needs of agricultural spray oil preparations. Poor hydrophilicity: Traditional water-soluble films are prone to swelling or losing strength in high humidity environments or when in contact with liquids, affecting the integrity and use effect of the packaging. Uneven film quality: The films prepared by the existing process have poor transparency and uneven thickness, which affects the appearance and functionality of the packaging. Poor storage stability: Ordinary water-soluble films are prone to aging or moisture absorption and deterioration during storage, resulting in performance degradation, which limits its scope of application. Insufficient environmental protection: Some water-soluble film materials are difficult to completely degrade, or the energy consumption during the production process is high, which does not meet the requirements of green environmental protection. The present invention improves the mechanical properties, hydrophilicity, film quality and storage stability of the water-soluble film by optimizing the raw material formula and preparation process, while ensuring its complete degradability to meet the actual needs of agricultural spray oil preparation packaging.

[0031] 2. Technical solution

[0032] To solve the above problems, the present invention adopts the following technical solutions.

[0033] A water-soluble film of an agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0034]

[0035] Wherein the plasticizer is polyethylene glycol or glycerol;

[0036] The emulsifier is Tween 80 or isomeric tridecanol polyoxyethylene ether;

[0037] Wherein the cross-linking agent is citric acid or borax;

[0038] Wherein the filler is talc or silicon dioxide;

[0039] The cosolvent is polyvinyl alcohol.

[0040] Preferably, the water-soluble film of the agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0041]

[0042] Wherein the plasticizer is polyethylene glycol or glycerol;

[0043] The emulsifier is Tween 80 or isomeric tridecanol polyoxyethylene ether;

[0044] The cross-linking agent is citric acid or borax;

[0045] Wherein the filler is talc or silicon dioxide;

[0046] The cosolvent is polyvinyl alcohol.

[0047] Preferably, the water-soluble film of the agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0048]

[0049] Wherein the plasticizer is polyethylene glycol or glycerol;

[0050] The emulsifier is Tween 80 or isomeric tridecanol polyoxyethylene ether;

[0051] The cross-linking agent is citric acid or borax;

[0052] Wherein the filler is talc or silicon dioxide;

[0053] The cosolvent is polyvinyl alcohol.

[0054] Preferably, the preparation method of modified corn starch is as follows:

[0055] The corn starch was ground into 1000 mesh, 10-20 times the mass of anhydrous ethanol was added, and the mixture was treated at a speed of 300-600 rpm and a constant temperature of 50-60°C for 2h-6h. Then, 0.2-0.6 times the mass of the corn starch and 0.01 times the mass of triacetin were added. The mixture was transferred to a reactor, and the mixture was reacted at 80-90°C for 6h-12h under 0.2MPa-0.4MPa, and then centrifuged at 6000rpm for 15min-20min. The precipitate was taken and vacuum freeze-dried to obtain a powder.

[0056] The method for preparing the water-soluble film of the agricultural spray oil preparation as described above comprises the following steps:

[0057] Add modified corn starch to deionized water, mix in a mass ratio of 1: (10-15), and stir to form starch milk; heat to 80℃-90℃, and form a uniform colloid base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloid base liquid, and continue stirring for 30min-60min to make them evenly dispersed and fully combined with the colloid base liquid; cool to 60℃-70℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 4.0-6.0, The reaction was maintained at 60°C for 1 hour to achieve cross-linking between starch molecules; the uniformly mixed solution was filtered through a 200-mesh filter to remove undissolved impurities, the filtered solution was evenly coated on a glass plate, and hot air dried at 60°C-80°C for 2h-3h to completely evaporate the water and form a continuous film. After drying, the water-soluble film was peeled off from the substrate and cut into individual packaging units of 25mL according to demand, and the cut water-soluble film was placed in a sealed packaging bag to prevent moisture absorption and deterioration.

[0058] Preferably, the coating thickness is controlled to be 7.6×10 -3 cm.

[0059] The use of the water-soluble film as described above in the preparation of agricultural spray oil preparations.

[0060] 3. Beneficial effects

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] The present invention uses a water-soluble film as a packaging material for agricultural spray oil preparations. The water-soluble film can be completely dissolved in the liquid medicine, and no recycling treatment is required, thereby avoiding the pollution caused by traditional plastic packaging to the environment. The water-soluble film is made of modified corn starch, which is a degradable material. It can be decomposed into carbon dioxide and water by microorganisms in the natural environment, and will not cause long-term harm to the soil, water bodies and ecosystems. The cost of water-soluble film packaging is significantly lower than that of traditional plastic packaging. Taking 1 liter of spray oil preparation as an example, the cost of water-soluble film packaging is 1.81 yuan, while the cost of plastic bottle packaging is 2.8 yuan, saving about 35.4% of the cost. The waste caused by the residual spray oil preparation on the inner wall of the plastic bottle is reduced, and the cost of use is further reduced. The water-soluble film packaging is designed as a small packaging unit for single use (such as 25mL), which does not need to be measured and can be directly put into the liquid medicine for use, greatly simplifying the dispensing operation process. Through precise dosage control, the problem of reduced efficacy or excessive use caused by inaccurate manual measurement is avoided. The water-soluble film material has good compatibility with the plant-derived glyceride spray oil preparation and does not affect the original efficacy. Experiments have shown that the water-soluble film itself has a certain repellent effect on pests and mites. After combining with plant-derived glycerides, it can further enhance the repellent effect on pests and improve the efficiency of pesticide application. The water-soluble film prepared by modified corn starch has high tensile strength and elongation at break, ensuring the stability and reliability of the packaging material. The modification process improves the hydrophilicity and storage stability of the water-soluble film, making it suitable for the actual needs in agricultural production. The present invention meets the needs of modern agriculture for green, environmentally friendly, efficient and convenient technologies, promotes the transformation of pesticide packaging from traditional plastics to degradable materials, and provides innovative solutions for the green development of agriculture. In summary, the present invention is superior to the prior art in terms of environmental protection, economy, ease of operation, enhanced efficacy and mechanical properties, and provides a new type of packaging form that is efficient, environmentally friendly and safe for agricultural spray oil preparations. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a sample picture of the water-soluble film prepared in Example 5. DETAILED DESCRIPTION

[0064] The present invention is further described below in conjunction with specific embodiments.

[0065] Unless otherwise defined, technical and scientific terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the invention belongs. In the present invention, parts by weight can be equivalent to the unit of weight kilogram.

[0066] Example 1

[0067] The water-soluble film of agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0068]

[0069] The plasticizer is polyethylene glycol;

[0070] The emulsifier is isomeric tridecanol polyoxyethylene ether;

[0071] The cross-linking agent is citric acid;

[0072] The filler is silicon dioxide;

[0073] The cosolvent is polyvinyl alcohol.

[0074] The preparation method of modified corn starch is as follows:

[0075] Grind the corn starch to 1000 mesh, add 10 times the mass of anhydrous ethanol, treat at 600 rpm and 50°C for 6 hours, then add 0.2 times the mass of corn starch polylactic acid monomer and 0.01 times the mass of triacetin, transfer to a reactor, react at 90°C for 6 hours at 0.2 MPa, then centrifuge at 6000 rpm for 15 minutes, take the precipitate, and vacuum freeze-dry to obtain powder.

[0076] The method for preparing the water-soluble film of the agricultural spray oil preparation as described above comprises the following steps:

[0077] Add modified corn starch to deionized water, mix in a mass ratio of 1:10, and stir to form starch milk; heat to 80℃, and form a uniform colloidal base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloidal base liquid, continue stirring for 30 minutes, so that it is evenly dispersed and fully combined with the colloidal base liquid; cool to 60℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 4.0, and keep 60℃ for 1h to achieve crosslinking between starch molecules; filter the mixed solution through a 200-mesh filter to remove undissolved impurities, and evenly coat the filtered solution on a glass plate, and dry it with hot air at 60℃ for 2h to evaporate the water completely and form a continuous film. After drying, peel the water-soluble film from the substrate and cut it into individual packaging units of 25mL according to needs. Place the cut water-soluble film in a sealed packaging bag to prevent moisture absorption and deterioration. The coating thickness is controlled to be 7.6×10 -3 cm.

[0078] Example 2

[0079] The water-soluble film of agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0080]

[0081] The plasticizer is glycerol;

[0082] The emulsifier is Tween 80;

[0083] The cross-linking agent is borax;

[0084] The filler is talcum powder;

[0085] The cosolvent is polyvinyl alcohol.

[0086] The preparation method of modified corn starch is as follows:

[0087] The corn starch was ground into 1000 mesh, 20 times the mass of anhydrous ethanol was added, and the mixture was treated at a speed of 600 rpm and a constant temperature of 50°C for 6 hours. Then, 0.6 times the mass of the corn starch and 0.01 times of triacetin were added. The mixture was transferred to a reactor, reacted at 80°C under 0.4 MPa for 12 hours, and then centrifuged at 6000 rpm for 20 minutes. The precipitate was taken and freeze-dried in vacuum to obtain a powder.

[0088] The method for preparing the water-soluble film of the agricultural spray oil preparation as described above comprises the following steps:

[0089] Add modified corn starch to deionized water, mix in a mass ratio of 1:15, and stir to form starch milk; heat to 90℃, and form a uniform colloidal base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloidal base liquid, continue stirring for 60 minutes, so that it is evenly dispersed and fully combined with the colloidal base liquid; cool to 70℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 6.0, and keep 60℃ for 1h to achieve crosslinking between starch molecules; filter the mixed solution through a 200-mesh filter to remove undissolved impurities, and evenly coat the filtered solution on a glass plate, and dry it with hot air at 80℃ for 3h to evaporate the water completely and form a continuous film. After drying, peel the water-soluble film from the substrate and cut it into individual packaging units of 25mL according to needs. Place the cut water-soluble film in a sealed packaging bag to prevent moisture absorption and deterioration. The coating thickness is controlled to be 7.6×10 -3 cm.

[0090] Example 3

[0091] The water-soluble film of agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0092]

[0093] The plasticizer is polyethylene glycol;

[0094] The emulsifier is Tween 80;

[0095] The cross-linking agent is citric acid;

[0096] The filler is talcum powder;

[0097] The cosolvent is polyvinyl alcohol.

[0098] The preparation method of modified corn starch is as follows:

[0099] Grind the corn starch to 1000 mesh, add 10 times the mass of anhydrous ethanol, treat at 300 rpm and 50°C for 2 h, then add 0.2 times the mass of corn starch polylactic acid monomer and 0.01 times the mass of triacetin, transfer to a reactor, react at 80°C under 0.2 MPa for 6 h, then centrifuge at 6000 rpm for 15 min, take the precipitate, and vacuum freeze-dry to obtain powder.

[0100] The method for preparing the water-soluble film of the agricultural spray oil preparation as described above comprises the following steps:

[0101] Add modified corn starch to deionized water, mix in a mass ratio of 1:10, and stir to form starch milk; heat to 80℃, and form a uniform colloidal base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloidal base liquid, continue stirring for 30 minutes, so that it is evenly dispersed and fully combined with the colloidal base liquid; cool to 60℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 4.0, and keep 60℃ for 1h to achieve crosslinking between starch molecules; filter the mixed solution through a 200-mesh filter to remove undissolved impurities, and evenly coat the filtered solution on a glass plate, and dry it with hot air at 60℃ for 2h to evaporate the water completely and form a continuous film. After drying, peel the water-soluble film from the substrate and cut it into individual packaging units of 25mL according to needs. Place the cut water-soluble film in a sealed packaging bag to prevent moisture absorption and deterioration. The coating thickness is controlled to be 7.6×10 -3 cm.

[0102] Example 4

[0103] The water-soluble film of agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0104]

[0105] The plasticizer is glycerol;

[0106] The emulsifier is isomeric tridecanol polyoxyethylene ether;

[0107] The cross-linking agent is borax;

[0108] The filler is silicon dioxide;

[0109] The cosolvent is polyvinyl alcohol.

[0110] The preparation method of modified corn starch is as follows:

[0111] The corn starch was ground into 1000 mesh, 20 times the mass of anhydrous ethanol was added, and the mixture was treated at a speed of 600 rpm and a constant temperature of 60°C for 6 hours. Then, 0.6 times the mass of the corn starch and 0.01 times of triacetin were added. The mixture was transferred to a reactor, reacted at 90°C for 12 hours at 0.4 MPa, and then centrifuged at 6000 rpm for 20 minutes. The precipitate was taken and freeze-dried in vacuum to obtain a powder.

[0112] The method for preparing the water-soluble film of the agricultural spray oil preparation as described above comprises the following steps:

[0113] Add modified corn starch to deionized water, mix in a mass ratio of 1:15, and stir to form starch milk; heat to 90℃, and form a uniform colloidal base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloidal base liquid, continue stirring for 60 minutes, so that it is evenly dispersed and fully combined with the colloidal base liquid; cool to 70℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 6.0, and keep 60℃ for 1h to achieve crosslinking between starch molecules; filter the mixed solution through a 200-mesh filter to remove undissolved impurities, and evenly coat the filtered solution on a glass plate, and dry it with hot air at 80℃ for 3h to evaporate the water completely and form a continuous film. After drying, peel the water-soluble film from the substrate and cut it into individual packaging units of 25mL according to needs. Place the cut water-soluble film in a sealed packaging bag to prevent moisture absorption and deterioration. The coating thickness is controlled to be 7.6×10 -3 cm.

[0114] Example 5

[0115] The water-soluble film of agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0116]

[0117] The plasticizer is glycerol;

[0118] The emulsifier is Tween 80;

[0119] The cross-linking agent is citric acid;

[0120] The filler is silicon dioxide;

[0121] The cosolvent is polyvinyl alcohol.

[0122] The preparation method of modified corn starch is as follows:

[0123] The corn starch was ground into 1000 mesh, 15 times the mass of anhydrous ethanol was added, and the mixture was treated at a speed of 500 rpm and a constant temperature of 55°C for 4 hours. Then, 0.4 times the mass of the corn starch and 0.01 times the mass of triacetin were added. The mixture was transferred to a reactor, reacted at 85°C for 10 hours at 0.23 MPa, and then centrifuged at 6000 rpm for 18 minutes. The precipitate was taken and freeze-dried in vacuum to obtain a powder.

[0124] The method for preparing the water-soluble film of the agricultural spray oil preparation as described above comprises the following steps:

[0125] Add modified corn starch to deionized water, mix in a mass ratio of 1:13, and stir to form starch milk; heat to 85℃, and form a uniform colloidal base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloidal base liquid, continue stirring for 50 minutes, so that it is evenly dispersed and fully combined with the colloidal base liquid; cool to 65℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 5.0, and keep 60℃ for 1h to achieve crosslinking between starch molecules; filter the mixed solution through a 200-mesh filter to remove undissolved impurities, and evenly coat the filtered solution on a glass plate, and dry it with hot air at 70℃ for 2.5h to evaporate the water completely and form a continuous film. After drying, peel the water-soluble film from the substrate and cut it into individual packaging units of 25mL according to needs. Place the cut water-soluble film in a sealed packaging bag to prevent moisture absorption and deterioration. The coating thickness is controlled to be 7.6×10 -3 cm.

[0126] Comparative Example 1

[0127] The water-soluble film of agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0128]

[0129] The plasticizer is glycerol;

[0130] The emulsifier is Tween 80;

[0131] The cross-linking agent is citric acid;

[0132] The filler is silicon dioxide;

[0133] The cosolvent is polyvinyl alcohol.

[0134] Comparative Example 2

[0135] The water-soluble film of agricultural spray oil preparation comprises the following raw materials in parts by weight:

[0136]

[0137] The plasticizer is glycerol;

[0138] The emulsifier is Tween 80;

[0139] The cross-linking agent is citric acid;

[0140] The filler is silicon dioxide;

[0141] The cosolvent is polyvinyl alcohol.

[0142] The preparation method of modified corn starch is as follows:

[0143] The corn starch was ground into 1000 mesh, 15 times the mass of anhydrous ethanol was added, and the mixture was treated at a speed of 500 rpm and a constant temperature of 55°C for 4 hours. Then, 0.4 times the mass of polyethylene monomer and 0.01 times the mass of triacetin were added. The mixture was transferred to a reactor, reacted at 85°C under 0.23 MPa for 10 hours, and then centrifuged at 6000 rpm for 18 minutes. The precipitate was taken and freeze-dried in vacuum to obtain a powder.

[0144] The method for preparing the water-soluble film of the agricultural spray oil preparation as described above comprises the following steps:

[0145] Add modified corn starch to deionized water, mix in a mass ratio of 1:13, and stir to form starch milk; heat to 85℃, and form a uniform colloidal base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloidal base liquid, continue stirring for 50 minutes, so that it is evenly dispersed and fully combined with the colloidal base liquid; cool to 65℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 5.0, and keep 60℃ for 1h to achieve crosslinking between starch molecules; filter the mixed solution through a 200-mesh filter to remove undissolved impurities, and evenly coat the filtered solution on a glass plate, and dry it with hot air at 70℃ for 2.5h to evaporate the water completely and form a continuous film. After drying, peel the water-soluble film from the substrate and cut it into individual packaging units of 25mL according to needs. Place the cut water-soluble film in a sealed packaging bag to prevent moisture absorption and deterioration. The coating thickness is controlled to be 7.6×10 -3 cm.

[0146] Detection scheme

[0147] Application of water-soluble film in the preparation of agricultural spray oil preparations:

[0148] Taking Example 5 as an example, Figure 1As shown in the figure, the actual product effect picture after preparing the water-soluble film to wrap the plant-based glyceride spray oil preparation shows that the water-soluble film has good quality. On the one hand, the water-soluble film is used to package the oil preparation, and the two are immiscible, so the packaging quality can be guaranteed. On the other hand, when the oil preparation is made into a solution for use, the water-soluble film can be dissolved in water to avoid environmental pollution.

[0149] Next, the mechanical properties of Examples 1-5 and Comparative Examples 1-2 were tested with reference to ASTM D882. The results are shown in Table 1 below:

[0150] Table 1 Mechanical properties test

[0151]

[0152] Comparative Example 1 selects ordinary corn starch, and the water-soluble film prepared from ordinary corn starch is insufficient in tensile strength and elongation at break. For example, the tensile strength of Comparative Example 1 is 22.9MPa, and the elongation at break is 180%, while the water-soluble film prepared from modified corn starch (such as Example 3) reaches 28.6MPa and 218%, respectively. This shows that ordinary corn starch is difficult to meet the requirements of high strength and high flexibility. Ordinary corn starch is easy to gelatinize after encountering water due to its ratio of amylose to amylopectin (about 28% amylose and 72% amylopectin), resulting in poor hydrophilicity of the film. The modified corn starch is treated by cross-linking or esterification to enhance the intermolecular binding force and improve the hydrophilic property. Ordinary corn starch is prone to uneven film quality and poor transparency during the film-forming process. This is because its particle structure is not optimized, and its dispersibility and emulsification ability are weak. In contrast, modified corn starch improves the film-forming quality through physical or chemical modification, making the film more uniform and transparent. The water-soluble film prepared from ordinary corn starch is prone to aging or dehydration during storage. This is because the high content of amylose and the lack of modification treatment lead to recrystallization between molecules. Modified corn starch effectively inhibits the aging phenomenon and improves storage stability by introducing cross-linking agents or other modification methods. Although ordinary corn starch itself is a natural material, its unmodified molecular structure makes it difficult to fully meet the mechanical performance requirements of degradable materials. Modified corn starch not only retains the degradable properties, but also significantly improves the application performance of the film, making it more suitable for environmentally friendly packaging purposes. Although ordinary corn starch is low-cost, it is inferior to modified corn starch in terms of mechanical properties, hydrophilicity, film-forming quality and storage stability. Therefore, in the high-demand water-soluble film packaging of agricultural spray oil preparations, choosing modified corn starch is a better solution.

[0153] In comparative example 2, polylactic acid monomer is replaced with polyethylene monomer. Polylactic acid (PLA) is a biodegradable material, and its ester bond can be decomposed into carbon dioxide and water in water or under the action of microorganisms, which is pollution-free to the environment. Polyethylene (PE) is a traditional petrochemical-based plastic with strong chemical stability and is difficult to degrade naturally. After replacement, the water-soluble film loses its degradability, does not meet environmental protection requirements, and may cause environmental pollution problems. Polylactic acid has good hydrophilicity and compatibility with modified corn starch, and can form a strong bond with starch molecules through ester bonds, thereby improving the uniformity and mechanical properties of the film. Polyethylene is a hydrophobic material and has poor compatibility with modified corn starch, which may cause phase separation in the film, thereby affecting the uniformity and transparency of the film. In addition, polyethylene requires higher processing temperatures, which may place higher requirements on the production process. The test results show that the tensile strength of the water-soluble film in Comparative Example 2 is 26.8MPa, and the elongation at break is 204%, which is improved compared to Comparative Example 1 (prepared with ordinary corn starch), but still lower than when polylactic acid monomer is used (such as tensile strength 28.6MPa, elongation at break 218%). The high crystallinity of polyethylene may enhance the rigidity of the film, but the lack of flexibility makes the film prone to breakage or damage in practical applications. Polylactic acid is widely used in the field of environmentally friendly packaging because it is derived from renewable resources and has good biodegradability, and meets the requirements of green development policies. After replacing with polyethylene, although the cost may be reduced, the environmental protection characteristics are lost, which is not suitable for the current agricultural and packaging market demand that focuses on sustainable development. After replacing the polylactic acid monomer with the polyethylene monomer, although the mechanical strength of the water-soluble film is improved, its flexibility, compatibility and biodegradability are significantly reduced. This change does not conform to the development trend of environmentally friendly packaging materials, and also weakens the application value of the material in the packaging of agricultural spray oil preparations. Therefore, from the perspective of comprehensive performance and market demand, polylactic acid monomer is still a better choice.

[0154] Water-soluble film enhanced repellency test

[0155] Test Materials:

[0156] Agricultural plant oil, water-soluble film, yellow striped flea beetle, wherein the agricultural plant oil can be one of methylated rapeseed oil, cottonseed oil, peanut oil, corn oil, soybean oil, sunflower seed oil, linseed oil and castor oil, which are just examples and not limiting.

[0157] Test method:

[0158] Set up 3 treatments.

[0159] Treatment 1: Put 2 leaves in a mesh bag, immerse 1 leaf in a solution containing water-soluble film and vegetable oil for 1 second, take out the other leaf without treatment, and then place it in parallel in the mesh bag. The vegetable oil content in the solution is 6.07 g / L, and the water-soluble film content is 0.53 g / L;

[0160] Treatment 2: Put two vegetable leaves in a net bag, immerse one in a solution containing vegetable oil, and leave the other untreated. The method is the same as treatment 1. The vegetable oil content in the solution is 6.07 g / L;

[0161] Treatment 3: Put two leaves in the net bag, immerse one leaf in the solution with water-soluble film for 1 second, and leave the other leaf untreated. The method is the same as treatment 1. The content of water-soluble film in the solution is 0.53 g / L;

[0162] Each treatment was repeated three times. Each net bag contained 30 adult yellow striped flea beetles, and the leaf area was basically the same. After 24 hours of treatment, the number of holes eaten by flea beetles on each leaf was counted.

[0163] The protection rate of the preparation on vegetable leaves from feeding by yellow striped flea beetles (%) = the number of holes eaten by flea beetles on untreated vegetable leaves / (the number of holes eaten by flea beetles on vegetable leaves treated with the preparation + the number of holes eaten by flea beetles on vegetable leaves not treated) × 100. Data were analyzed for significant differences by paired sample T test and one-way analysis of variance using SPSS software.

[0164] 2. Test results

[0165] The test results showed that the number of holes made by flea beetles on the leaves of each treatment was significantly less than that of the control (Table 1), indicating that the water-soluble film, vegetable oil, and vegetable oil + water-soluble film all had a certain repelling effect on flea beetles gnawing on the leaves, and could protect the leaves from being gnawed by flea beetles. The vegetable oil + water-soluble film treatment had the best effect, with 0 holes made by flea beetles on the leaves treated with it, and the protection rate of the leaves reached 100% (Table 2).

[0166] Table 1 Number of holes made by yellow flea beetles on vegetable leaves in each treatment

[0167] deal with Number of holes in the leaves for soaking medicine Number of holes in untreated leaves T-value Vegetable oil + water-soluble film 0.00±0.00 53.33±13.58 0.021 Vegetable oil 1.67±2.89 54.67±19.55 0.035 Water-soluble film 24.67±9.07 73.33±24.12 0.046

[0168] Note: The data in the table are mean ± standard error. Paired sample T test

[0169] Table 2 Protection rate of the preparations against the yellow striped flea beetle feeding on vegetable leaves (%)

[0170] deal with Protection rate of the preparation on vegetable leaves (%) Vegetable oil + water-soluble film 100.00±0.00 a Vegetable oil 97.81±2.19 a Water-soluble film 74.23±6.34 b

[0171] Note: The data in the table are mean ± standard error. The mean values ​​with the same letters in the same column are not significantly different (P>0.05, Tukey method).

[0172] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field of degradable film materials to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope determined by the claims submitted by the present invention.

Claims

1. A water-soluble film of an agricultural spray oil preparation, characterized in that: In parts by weight, the following raw materials are included: Wherein the plasticizer is polyethylene glycol or glycerol; The emulsifier is Tween 80 or isomeric tridecanol polyoxyethylene ether; The cross-linking agent is citric acid or borax; Wherein the filler is talc or silicon dioxide; The cosolvent is polyvinyl alcohol.

2. The water-soluble film of the agricultural spray oil preparation according to claim 1, characterized in that: In parts by weight, the following raw materials are included: Wherein the plasticizer is polyethylene glycol or glycerol; The emulsifier is Tween 80 or isomeric tridecanol polyoxyethylene ether; The cross-linking agent is citric acid or borax; Wherein the filler is talc or silicon dioxide; The cosolvent is polyvinyl alcohol.

3. The water-soluble film of the agricultural spray oil preparation according to claim 2, characterized in that: In parts by weight, the following raw materials are included: Wherein the plasticizer is polyethylene glycol or glycerol; The emulsifier is Tween 80 or isomeric tridecanol polyoxyethylene ether; The cross-linking agent is citric acid or borax; Wherein the filler is talc or silicon dioxide; The cosolvent is polyvinyl alcohol.

4. The water-soluble film of the agricultural spray oil preparation according to claim 3, characterized in that: The preparation method of modified corn starch is as follows: The corn starch was ground into 1000 mesh, 10-20 times the mass of anhydrous ethanol was added, and the mixture was treated at a speed of 300-600 rpm and a constant temperature of 50-60°C for 2h-6h. Then, 0.2-0.6 times the mass of the corn starch and 0.01 times the mass of triacetin were added. The mixture was transferred to a reactor, and the mixture was reacted at 80-90°C for 6h-12h under 0.2MPa-0.4MPa, and then centrifuged at 6000rpm for 15min-20min. The precipitate was taken and vacuum freeze-dried to obtain a powder.

5. A method for preparing a water-soluble film of an agricultural spray oil formulation according to any one of claims 1 to 4, The following steps are involved: Add modified corn starch to deionized water, mix in a mass ratio of 1: (10-15), and stir to form starch milk; heat to 80℃-90℃, and form a uniform colloid base liquid under continuous stirring; slowly add plasticizer and cosolvent to the gelatinized colloid base liquid, and continue stirring for 30min-60min to make them evenly dispersed and fully combined with the colloid base liquid; cool to 60℃-70℃, add emulsifier and filler, and stir evenly; add crosslinking agent, adjust pH to 4.0-6.0, The reaction was maintained at 60°C for 1 hour to achieve cross-linking between starch molecules; the uniformly mixed solution was filtered through a 200-mesh filter to remove undissolved impurities, the filtered solution was evenly coated on a glass plate, and hot air dried at 60°C-80°C for 2h-3h to completely evaporate the water and form a continuous film. After drying, the water-soluble film was peeled off from the substrate and cut into individual packaging units of 25mL according to demand, and the cut water-soluble film was placed in a sealed packaging bag to prevent moisture absorption and deterioration.

6. The method for preparing a water-soluble film of an agricultural spray oil formulation according to claim 5, characterized in that: Control coating thickness to 7.6×10 -3 cm.

7. Use of the water-soluble film as claimed in claim 1 in preparing agricultural spray oil preparations.

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