PHA-based medical fertilizer molasses composite quick-start sustained-release preparation

Abstract

The invention discloses a PHA-based medical fertilizer molasses composite quick-start sustained-release preparation, and belongs to the technical field of crop sustained-release preparations. The crop slow-release preparation is used for solving the technical problem that the NPK nutrient utilization rate, the pesticide composition utilization rate, the early-stage control / fertilizer supply high efficiency and the later-stage control / fertilizer supply continuity of a crop slow-release preparation in the prior art need to be further improved. The crop slow-release preparation specifically comprises bifunctional core particles, a PHA-based slow-release layer and a quick-release starting layer which are sequentially arranged from inside to outside. By constructing a multi-layer composite structure of the bifunctional core particles, the PHA-based slow-release layer and the quick-release starting layer and optimizing the components of each layer, the preparation can quickly take effect and stably supply effective components for a long time after being applied, so that the pesticide utilization rate and the nutrient absorption efficiency are remarkably improved, the action period is prolonged, the residual risk is reduced, and the economic benefit is increased. Finally, the efficient, controllable and environment-friendly pesticide-fertilizer synergistic release effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of sustained-release formulations for crops, specifically to a rapid-release sustained-release formulation of a PHA-based drug fertilizer molasses compound. Background Technology

[0002] In current agricultural production, in order to simultaneously meet the nutrient requirements for crop growth and development as well as the requirements for pest and weed control, it is usually necessary to apply fertilizers, including single-element fertilizers, special-effect fertilizers, and compound fertilizers, and pesticides, including insecticides, fungicides, and herbicides, or to use simple mixed fertilizer-pesticide compound preparations. Although this type of input can take into account both fertilization and control to a certain extent, in practice, it still generally suffers from problems such as high application frequency, high labor intensity, low utilization rate of effective ingredients, and heavy environmental pressure, making it difficult to meet the comprehensive requirements of green and efficient agriculture for reduced dosage, increased efficiency, sustainability, and low residue.

[0003] Currently, traditional single-element fertilizers mainly provide nitrogen, phosphorus, potassium, and some micronutrients, offering only nutritional supply without pest and disease control. Furthermore, due to factors such as soil fixation, leaching, and volatilization, fertilizer utilization rates are generally low (commonly around 30-40% in production practice), resulting in low crop absorption efficiency and significant resource waste. Traditional single-element pesticides are prone to volatilization, photodegradation, hydrolysis, runoff, and leaching in the field environment, often exhibiting short-lasting effects and requiring repeated application, thereby increasing the risk of environmental pollution and the difficulty of controlling agricultural product residues. Moreover, most common compound fertilizer-pesticide formulations are physical mixtures of fertilizers and pesticides or simple co-granulated products, lacking a structured design targeting release behavior. They either have a fast onset of action but a short duration of effect and insufficient subsequent supply, or a prolonged release cycle that makes it difficult to quickly meet the nutritional and control window requirements of seedlings, resulting in nutrient gaps in seedlings or the risk of outbreaks of diseases, pests, and weeds. Although some slow-release fertilizers and pesticides can achieve a certain slow-release effect, their release rate is unstable. At the same time, these products mostly focus on slow-release fertilization / pesticide delivery, lacking a systematic design for promoting root growth and improving absorption efficiency. During plant growth, there is a risk of fertilization interruption and weed regeneration, making it difficult to significantly improve crop root vitality, stress resistance, and actual absorption and utilization of nutrients / pesticides.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a PHA-based pesticide-fertilizer-molasses compound fast-release formulation to address the technical problems in existing crop slow-release formulations where the NPK nutrient utilization rate, pesticide composition utilization rate, early-stage control / fertilization efficiency, and late-stage control / fertilization continuity need further improvement.

[0006] The objective of this invention can be achieved through the following technical solution: a PHA-based drug molasses compound rapid-release sustained-release formulation, comprising, from the inside out: a dual-function core particle, a PHA-based sustained-release layer, and a rapid-release initiation layer; The bifunctional core particles comprise the following components by weight: 40-50 parts of nutrients, 5-10 parts of core pesticide composition, 15-25 parts of HMC-modified kaolin, and 3-5 parts of binder. The thickness of the PHA-based sustained-release layer is 100-200 μm; The rapid release initiation layer comprises the following components by weight: 50-60 parts molasses, 8-15 parts outer pesticide composition, and 10-20 parts fast-acting nutrients, with a thickness of 60-120 μm.

[0007] Furthermore, the nutrient elements are composed of urea, monoammonium phosphate, potassium sulfate, boric acid, zinc sulfate, and EDTA-iron in a weight ratio of 10-15:12-16:10-15:0.5-0.8:1-1.5:0.6-0.8; the core pesticide composition is any one or more of herbicides, fungicides, and insecticides, wherein the herbicide is one or a mixture of two of glyphosate and nicosulfuron, the fungicide is one or a mixture of two of carbendazim and pyraclostrobin, and the insecticide is one or a mixture of two of imidacloprid and chlorantraniliprole.

[0008] Furthermore, the PHA-based sustained-release layer comprises the following components in parts by weight: 65-75 parts PHA, 35-45 parts PBAT, 10-15 parts hydroxypropyl starch, and 8-10 parts montmorillonite.

[0009] Furthermore, the outer pesticide layer is composed of any one or more of herbicides, fungicides, and insecticides. The herbicide is one or a mixture of two of glyphosate and nicosulfuron, the fungicide is one or a mixture of two of carbendazim and pyraclostrobin, and the insecticide is one or a mixture of two of imidacloprid and chlorantraniliprole. The fast-acting nutrient element is composed of ammonium sulfate, potassium dihydrogen phosphate, and potassium chloride in a weight ratio of 6-8:6-8:3-4.

[0010] Furthermore, the preparation method of the HMC modified kaolin is as follows: under the protection of an inert gas atmosphere, hydroxymethyl cellulose and N,N-dimethylformamide are mixed and stirred until the system is dissolved. Propyltriethoxysilane isocyanate and activated kaolin are added to the reaction system. The reaction system is heated to 60-70℃ and kept at this temperature for 30-50 min. Alkali solution is added to the reaction system and kept at this temperature for 40-60 min. After post-treatment, HMC modified kaolin is obtained.

[0011] Furthermore, the ratio of hydroxymethyl cellulose, N,N-dimethylformamide, propyltriethoxysilane isocyanate, activated kaolin, and alkali solution is 3-4 g:50 mL:0.9-1.2 g:5-6 g:5 mL, and the alkali solution is a 2-3 mol / L sodium hydroxide solution. The post-treatment includes: after the reaction is complete, cooling the reaction system to room temperature, adding anhydrous ethanol to the reaction system, stirring and dispersing for 30-50 min, filtering, washing the filter cake three times with 80 vol% ethanol aqueous solution, drying it, transferring the filter cake to a drying oven at 60-70℃, and drying it to constant weight to obtain HMC modified kaolin.

[0012] Furthermore, activated kaolin is obtained through the following steps: A1. Mix kaolin and sulfuric acid solution, heat the reaction system to 80-90℃, keep it at the temperature and stir for 3-4 hours, and then perform post-treatment to obtain pretreated kaolin. A2. Mix the pretreated kaolin and the activation solution, heat the reaction system to 60-70℃, keep it warm and stir for 2-3 hours, and then perform post-treatment to obtain activated kaolin.

[0013] Further, in step A1, the solid-liquid ratio of the kaolin and the sulfuric acid solution is 1:3-5, and the sulfuric acid solution is composed of 15-20wt% sulfuric acid and sodium dodecyl sulfate at a ratio of 50mL:1g. The post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, transferred to a drying oven at a temperature of 70-80℃, dried to constant weight, ground, and passed through a 200-mesh sieve to obtain pretreated kaolin.

[0014] Further, in step A2, the solid-liquid ratio of the pretreated kaolin and the activation solution is 1:8-10. The activation solution is composed of calcium chloride, magnesium chloride and deionized water in a ratio of 2g:1g:100mL. The post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, and then transferred to a drying oven at a temperature of 70-80℃. After drying to constant weight, activated kaolin is obtained.

[0015] Furthermore, the PHA-based drug-molasses compound rapid-release formulation is prepared by the following steps: S1. Add nutrients, pesticide components, HMC-modified kaolin and binder to a mixer and mix for 15-20 minutes to obtain a mixed base material. Add deionized water to the mixer and mix for 8-10 minutes. Then feed it into a granulator to granulate and obtain bifunctional core particles with a particle size of 2-5 mm. S2. Mix PHA, PBAT, emulsifier and ethanol, heat the reaction system to 50-60℃, stir and disperse for 20-30 min, add a mixed slurry composed of hydroxypropyl starch, montmorillonite and deionized water to the reaction system, emulsify and disperse for 40-50 min to obtain the coating solution. Mix molasses, pesticide components, fast-acting nutrients, emulsifier and deionized water, emulsify and disperse for 10-15 minutes to obtain molasses-based suspension; S3. Place the bifunctional core particles in a fluidized bed coating machine. Spray the coating solution into the fluidized bed coating machine in the form of atomization. After spraying, dry for 15-20 minutes to form a PHA-based sustained-release layer coating on the outside of the bifunctional core particles. Then, spray the molasses-based suspension into the fluidized bed coating machine in the form of atomization. After spraying, dry until the moisture content is below 3% to form a rapid-release initiation layer coating on the PHA-based sustained-release layer, thus obtaining a PHA-based drug-fertilizer-molasses composite rapid-release sustained-release formulation.

[0016] The present invention has the following beneficial effects: 1. This invention utilizes a multi-layered composite structure consisting of a dual-functional core particle, a PHA-based slow-release layer, and a rapid-release initiation layer arranged sequentially from the inside out. The rapid-release initiation layer, a molasses-based suspension layer, loads readily available nutrients and pesticides from the outer layer. Upon entering the soil, it rapidly swells / dissolves and releases, quickly forming a peak in available nutrients and efficacy during the seedling stage or early weed infestation, ensuring rapid initiation. Subsequently, the PHA-based slow-release layer takes over and stably outputs nutrients, maintaining continuous supply in the mid-to-late stages. Simultaneously, the HMC-modified kaolin in the dual-functional core particle adsorbs, fixes, and regulates the re-release of pesticides and fertilizers, preventing excessive burst release or migration losses due to the rapid release from the outer layer. The multi-layered structure achieves a synergistic effect of the outer layer compensating for early-stage demand, the slow-release layer ensuring sustained supply, and the core layer regulating and reducing losses. The biodegradable nature of the PHA system also effectively reduces the risk of organic residues, thus achieving early control and increasing the utilization rate of NPK and pesticide components without increasing the environmental residue burden, achieving a balance between early control / promoting growth and stable yield in the later stages.

[0017] 2. This invention also pre-treats the kaolin to expose and homogenize the surface hydroxyl active sites, and then processes it with Ca... 2+ / Mg 2+Activation enhances surface reactivity and ion bridging ability, ultimately achieving stable connection between the inorganic surface and hydroxymethyl cellulose segments via propyltriethoxysilane isocyanate, forming a modified layer with both amphiphilic and multi-point interaction capabilities. HMC-modified kaolin forms a more stable adsorption and fixation of pesticides such as nicosulfuron and some nutrients through hydrogen bonding / weak interactions and hydration layer effects, inhibiting burst release, migration, and non-targeted loss. Furthermore, as a "flexible interface layer," HMC-modified kaolin significantly improves the compatibility and adhesion strength between the core and the subsequent polymer coating, reducing coating defects and interlayer debonding, thereby improving the utilization rate of composite formulation materials and NPK nutrient utilization, and promoting crop root absorption and growth performance.

[0018] 3. This invention also uses a continuous biodegradable polymer membrane formed by PHA and PBAT as the main control barrier layer, and introduces components such as montmorillonite and hydroxypropyl starch: the layered structure of montmorillonite can significantly increase diffusion tortuosity and prolong the mass transfer path of water and solute, thereby reducing direct penetration and making the release more gradual; hydroxypropyl starch improves the wettability and adhesion of the coating, regulates the microphase structure and pore formation, so that the membrane layer can maintain a dense barrier while avoiding insufficient supply caused by complete closure; the interface of the PHA-based slow-release layer and the bifunctional core particles is coupled to make the membrane layer quality more stable and the release curve more predictable, thus showing a more stable nutrient release period and pesticide retention period in the field, reducing the risk of late greening, recurrence or fertilizer supply interruption, and further promoting root fertilization and overall fertilizer efficiency improvement. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] In this invention, PHA is a polyhydroxyalkanoate with an effective ingredient content of 99.9%, selected from commercially available products of Dongguan Zhangmutou Hengtai Plastic Raw Materials Business Department; In this invention, the effective ingredient content of PBAT is 99.9%, and it is selected from commercially available products of Zibo Yujin Trading Co., Ltd. In this invention, the active ingredient content of hydroxypropyl starch is 99%, and it is selected from commercially available products of Hubei Haijia Biotechnology Co., Ltd.

[0021] Example 1 This embodiment provides a method for preparing HMC-modified kaolin, including the following steps: Step 1: Preparation of pretreated kaolin 15wt% sulfuric acid and sodium dodecyl sulfate were mixed evenly at a ratio of 50mL:1g to obtain a sulfuric acid solution; Kaolin and sulfuric acid solution were added to a reaction flask at a solid-liquid ratio of 1:3 and stirred. The reaction flask was heated to 80°C and stirred for 3 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 70°C. After drying to constant weight, it was ground and passed through a 200-mesh sieve to obtain pretreated kaolin.

[0022] Step 2: Preparation of activated kaolin Calcium chloride, magnesium chloride and deionized water were mixed evenly at a ratio of 2g:1g:100mL to obtain an activation solution; Pretreated kaolin and activation solution were added to a reaction flask at a solid-liquid ratio of 1:8 and stirred. The reaction flask was heated to 60°C and stirred for 2 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 70°C. After drying to constant weight, activated kaolin was obtained.

[0023] Step 3: Preparation of HMC-modified kaolin Weigh 30g of hydroxymethyl cellulose and 500mL of N,N-dimethylformamide and add them to a reaction flask under argon protection. Stir until the system is dissolved. Add 9g of propyltriethoxysilane isocyanate and 50g of activated kaolin to the reaction flask. Heat the reaction flask to 60℃ and keep it at that temperature for 30min. Add 50mL of 2mol / L sodium hydroxide solution to the reaction flask and keep it at that temperature for 40min. Cool the reaction flask to room temperature and add 1000mL of anhydrous ethanol to the reaction flask. Stir and disperse for 30min. Filter the mixture. Wash the filter cake three times with 80vol% ethanol aqueous solution and dry it under vacuum. Transfer the filter cake to a drying oven at 60℃ and dry it to constant weight to obtain HMC modified kaolin.

[0024] In the reaction, kaolin is acid-washed with sulfuric acid at a relatively high temperature, dissolving some impurities / soluble components and cleaning the surface while promoting the exposure and activation of surface hydroxyl groups. Sodium dodecyl sulfate acts as a wetting and dispersing agent, reducing agglomeration and making the acid treatment more uniform, thus providing more reactive sites for subsequent coupling. The introduced CaCl2 and MgCl2 ionize the acid-treated surface. 2+ / Mg 2+Charge compensation and ion bridges can be formed at negatively charged layers / edge sites of kaolin, enhancing the stability and reaction accessibility of surface polar sites and facilitating the subsequent directional occurrence of silane hydrolysis and condensation on the solid surface. Then, hydroxymethyl cellulose is dissolved in N,N-dimethylformamide to form a homogeneous reaction system. The isocyanate groups of propyltriethoxysilane undergo addition reactions with the hydroxyl groups on the hydroxymethyl cellulose molecular chain to form urethane bonds, introducing the triethoxysilane end group onto the hydroxymethyl cellulose chain. Subsequently, alkali solution is added to promote the hydrolysis of siloxane bonds into silanols, which further react with the kaolin surface. Condensation generates covalent bonds, constructing a hybrid graft layer of inorganic substrate and hydroxymethyl cellulose (HMC) polymer segments on the surface of kaolin. The surface energy and wettability of HMC-modified kaolin are regulated, particle dispersibility and anti-agglomeration are enhanced, and interfacial bonding and film adhesion are improved. At the same time, HMC segments provide multiple hydrogen bond / adsorption sites and a certain diffusion retardation effect, transforming kaolin from an inert filler into a functional carrier that combines interfacial compatibility, adsorption and temporary storage, and enhanced coating integrity. This is beneficial for subsequent coating densification, reducing defects such as pinhole cracks, and improving controlled-release stability and utilization efficiency of effective components.

[0025] Example 2 This embodiment provides a method for preparing HMC-modified kaolin, including the following steps: Step 1: Preparation of pretreated kaolin 17wt% sulfuric acid and sodium dodecyl sulfate were mixed evenly at a ratio of 50mL:1g to obtain a sulfuric acid solution; Kaolin and sulfuric acid solution were added to a reaction flask at a solid-liquid ratio of 1:4 and stirred. The reaction flask was heated to 85°C and stirred for 3.5 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 75°C. After drying to constant weight, it was ground and passed through a 200-mesh sieve to obtain pretreated kaolin.

[0026] Step 2: Preparation of activated kaolin Calcium chloride, magnesium chloride and deionized water were mixed evenly at a ratio of 2g:1g:100mL to obtain an activation solution; Pretreated kaolin and activation solution were added to a reaction flask at a solid-liquid ratio of 1:9 and stirred. The reaction flask was heated to 65°C and stirred for 2.5 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 75°C. After drying to constant weight, activated kaolin was obtained.

[0027] Step 3: Preparation of HMC-modified kaolin Weigh out 35g of hydroxymethyl cellulose and 500mL of N,N-dimethylformamide and add them to a reaction flask under argon protection. Stir until the system is dissolved. Add 10.5g of propyltriethoxysilane isocyanate and 55g of activated kaolin to the reaction flask. Heat the reaction flask to 65℃ and keep it at that temperature for 40min. Add 50mL of 2.5mol / L sodium hydroxide solution to the reaction flask and keep it at that temperature for 50min. Cool the reaction flask to room temperature and add 1000mL of anhydrous ethanol. Stir and disperse for 40min. Filter the mixture. Wash the filter cake three times with 80vol% ethanol aqueous solution and dry it under vacuum. Transfer the filter cake to a drying oven at 65℃ and dry it to constant weight to obtain HMC modified kaolin.

[0028] Example 3 This embodiment provides a method for preparing HMC-modified kaolin, including the following steps: Step 1: Preparation of pretreated kaolin 20wt% sulfuric acid and sodium dodecyl sulfate were mixed evenly at a ratio of 50mL:1g to obtain a sulfuric acid solution; Kaolin and sulfuric acid solution were added to a reaction flask at a solid-liquid ratio of 1:5 and stirred. The reaction flask was heated to 90°C and stirred for 4 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 80°C. After drying to constant weight, it was ground and passed through a 200-mesh sieve to obtain pretreated kaolin.

[0029] Step 2: Preparation of activated kaolin Calcium chloride, magnesium chloride and deionized water were mixed evenly at a ratio of 2g:1g:100mL to obtain an activation solution; Pretreated kaolin and activation solution were added to a reaction flask at a solid-liquid ratio of 1:10 and stirred. The reaction flask was heated to 70°C and stirred for 3 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 80°C. After drying to constant weight, activated kaolin was obtained.

[0030] Step 3: Preparation of HMC-modified kaolin Weigh 40g of hydroxymethyl cellulose and 500mL of N,N-dimethylformamide and add them to a reaction flask under argon protection. Stir until the system is dissolved. Add 12g of propyltriethoxysilane isocyanate and 60g of activated kaolin to the reaction flask. Heat the reaction flask to 70℃ and keep it at that temperature for 50min. Add 50mL of 3mol / L sodium hydroxide solution to the reaction flask and keep it at that temperature for 60min. Cool the reaction flask to room temperature and add 1000mL of anhydrous ethanol to the reaction flask. Stir and disperse for 50min. Filter the mixture. Wash the filter cake three times with 80vol% ethanol aqueous solution and dry it under vacuum. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain HMC modified kaolin.

[0031] Example 4 This embodiment provides a method for preparing a rapid-release, sustained-release formulation of a PHA-based pesticide-fertilizer-molasses compound suitable for weed control in corn fields, including the following steps: Step S1: Preparation of bifunctional core particles Urea, monoammonium phosphate, potassium sulfate, boric acid, zinc sulfate, and EDTA-iron are mixed evenly in a weight ratio of 10:12:10:0.5:1:0.6 to obtain the nutrient elements. The pesticide composition is based on nicosulfuron as the core. Weigh out the following by weight: 40 parts of nutrient elements, 5 parts of core pesticide composition, 15 parts of HMC modified kaolin prepared in Example 1, and 3 parts of binder starch. Add them to the mixer, set the mixer speed to 60 r / min, and mix for 15 min to obtain the mixed base material. Add 10% of the weight of the mixed base material to the mixer and continue mixing for 8 minutes. Then, feed it into the granulator to form particles with a diameter of 2-5 mm. Then, send the formed particles into a dryer at a temperature of 60℃ to dry until the moisture content is ≤5%, and obtain bifunctional core particles with a diameter of 2-5 mm.

[0032] Step S2: Preparation of coating solution Weigh out the following components by weight: 10 parts hydroxypropyl starch, 8 parts montmorillonite, and 50 parts deionized water, mix them evenly, and obtain a mixed slurry. Weigh out the following components by weight: 65 parts PHA, 35 parts PBAT, 6 parts Tween-80, 2.2 parts sodium dodecyl sulfate, and 500 parts ethanol. Add these components to a reaction flask and stir. Heat the reaction flask to 50°C and stir for 20 minutes. Increase the stirring speed to 1000 r / min. Add the prepared slurry to the reaction flask and emulsify and disperse for 40 minutes to obtain the coating solution.

[0033] Step S3: Prepare honey-based suspension Ammonium sulfate, potassium dihydrogen phosphate, and potassium chloride are mixed evenly in a weight ratio of 6:6:3 to obtain fast-acting nutrients. It is composed of nicosulfuron as the outer layer pesticide; Weigh out the following components by weight: 50 parts molasses, 8 parts outer pesticide components, 10 parts fast-acting nutrients, 5 parts Tween-80, 2 parts sodium dodecyl sulfate, and 500 parts deionized water. Add these components to a reaction flask and stir. Set the stirring speed to 1000 r / min and emulsify and disperse for 10 min to obtain a molasses-based suspension.

[0034] Step S4: Preparation of the compound formulation The bifunctional core particles were placed in a fluidized bed coating machine with an inlet air temperature of 45℃ and an outlet air temperature of 30℃. The coating solution was atomized at a pressure of 0.3MPa and then sprayed into the fluidized bed coating machine. After spraying, the mixture was dried for 15 minutes to form a 100-200μm thick PHA-based sustained-release layer on the outside of the bifunctional core particles. Then, a molasses-based suspension was atomized at a pressure of 0.2MPa and sprayed into the fluidized bed coating machine. After spraying, the mixture was dried until the moisture content was below 3% to form a 60-120μm thick rapid-release initiation layer on the PHA-based sustained-release layer, thus obtaining a PHA-based drug-fertilizer-molasses composite rapid-release sustained-release formulation.

[0035] Example 5 This embodiment provides a method for preparing a rapid-release, sustained-release formulation of a PHA-based pesticide-fertilizer-molasses compound suitable for weed control in corn fields, including the following steps: Step S1: Preparation of bifunctional core particles Urea, monoammonium phosphate, potassium sulfate, boric acid, zinc sulfate, and EDTA-iron are mixed evenly in a weight ratio of 13:14:13:0.65:1.3:0.7 to obtain the nutrient elements. The pesticide composition is based on nicosulfuron as the core. Weigh out the following by weight: 45 parts of nutrient elements, 7 parts of core pesticide composition, 20 parts of HMC modified kaolin prepared in Example 2, and 4 parts of binder starch. Add them to the mixer, set the mixer speed to 70 r / min, and mix for 17 min to obtain the mixed base material. Add deionized water to the mixer at 13% of the weight of the mixed base material, continue mixing for 9 minutes, then feed it into the granulator to form particles with a diameter of 2-5 mm. Then send the formed particles into a dryer at a temperature of 70℃ to dry until the moisture content is ≤5%, to obtain bifunctional core particles with a diameter of 2-5 mm.

[0036] Step S2: Preparation of coating solution Weigh out the following components by weight: 13 parts hydroxypropyl starch, 9 parts montmorillonite, and 50 parts deionized water, mix them evenly, and obtain a mixed slurry. Weigh out the following components by weight: 70 parts PHA, 40 parts PBAT, 7 parts Tween-80, 2.6 parts sodium dodecyl sulfate, and 500 parts ethanol. Add these components to a reaction flask and stir. Heat the reaction flask to 55°C and stir for 25 minutes. Increase the stirring speed to 1250 r / min. Add the prepared slurry to the reaction flask and emulsify and disperse for 45 minutes to obtain the coating solution.

[0037] Step S3: Prepare honey-based suspension Ammonium sulfate, potassium dihydrogen phosphate, and potassium chloride are mixed evenly in a weight ratio of 7:7:3.5 to obtain fast-acting nutrients. It is composed of nicosulfuron as the outer layer pesticide; Weigh out the following components by weight: 55 parts molasses, 12 parts outer pesticide components, 15 parts fast-acting nutrients, 6 parts Tween-80, 2.5 parts sodium dodecyl sulfate, and 500 parts deionized water. Add these components to a reaction flask and stir. Set the stirring speed to 1250 r / min and emulsify and disperse for 13 min to obtain a molasses-based suspension.

[0038] Step S4: Preparation of the compound formulation The bifunctional core particles were placed in a fluidized bed coating machine with an inlet air temperature of 47°C and an outlet air temperature of 35°C. The coating solution was atomized at a pressure of 0.4 MPa and then sprayed into the fluidized bed coating machine. After spraying, the mixture was dried for 17 minutes to form a 100-200 μm thick PHA-based sustained-release layer on the outside of the bifunctional core particles. Then, a molasses-based suspension was atomized at a pressure of 0.3 MPa and sprayed into the fluidized bed coating machine. After spraying, the mixture was dried until the moisture content was below 3% to form a 60-120 μm thick rapid-release initiation layer on the PHA-based sustained-release layer, thus obtaining a PHA-based drug-fertilizer-molasses composite rapid-release sustained-release formulation.

[0039] Example 6 This embodiment provides a method for preparing a rapid-release, sustained-release formulation of a PHA-based pesticide-fertilizer-molasses compound suitable for weed control in corn fields, including the following steps: Step S1: Preparation of bifunctional core particles Urea, monoammonium phosphate, potassium sulfate, boric acid, zinc sulfate, and EDTA-iron are mixed evenly in a weight ratio of 15:16:15:0.8:1.5:0.8 to obtain the nutrient elements. The pesticide composition is based on nicosulfuron as the core. Weigh out the following by weight: 50 parts of nutrient elements, 10 parts of core pesticide composition, 25 parts of HMC modified kaolin prepared in Example 3, and 5 parts of binder starch. Add them to the mixer, set the mixer speed to 80 r / min, and mix for 20 min to obtain the mixed base material. Add 15% of the weight of the mixed base material to the mixer and continue mixing for 10 minutes. Then, feed it into the granulator to form particles with a diameter of 2-5 mm. Then, send the formed particles into a dryer at a temperature of 80℃ to dry until the moisture content is ≤5%, and obtain bifunctional core particles with a diameter of 2-5 mm.

[0040] Step S2: Preparation of coating solution Weigh out the following components by weight: 15 parts hydroxypropyl starch, 10 parts montmorillonite, and 50 parts deionized water, mix them evenly, and obtain a mixed slurry. Weigh out the following components by weight: 75 parts PHA, 45 parts PBAT, 8 parts Tween-80, 3 parts sodium dodecyl sulfate, and 500 parts ethanol. Add these components to a reaction flask and stir. Heat the reaction flask to 60°C and stir for 30 minutes. Increase the stirring speed to 1500 r / min. Add the prepared slurry to the reaction flask and emulsify and disperse for 50 minutes to obtain the coating solution.

[0041] Step S3: Prepare honey-based suspension Ammonium sulfate, potassium dihydrogen phosphate, and potassium chloride are mixed evenly in a weight ratio of 8:8:4 to obtain fast-acting nutrients. It is composed of nicosulfuron as the outer layer pesticide; Weigh out the following components by weight: 60 parts molasses, 15 parts outer pesticide composition, 20 parts fast-acting nutrient elements, 7 parts Tween-80, 3 parts sodium dodecyl sulfate, and 500 parts deionized water. Add these components to a reaction flask and stir. Set the stirring speed to 1500 r / min and emulsify and disperse for 15 min to obtain a molasses-based suspension.

[0042] Step S4: Preparation of the compound formulation The bifunctional core particles were placed in a fluidized bed coating machine with an inlet air temperature of 50°C and an outlet air temperature of 40°C. The coating solution was atomized at a pressure of 0.5 MPa and then sprayed into the fluidized bed coating machine. After spraying, the mixture was dried for 20 minutes to form a 100-200 μm thick PHA-based sustained-release layer on the outside of the bifunctional core particles. Then, a molasses-based suspension was atomized at a pressure of 0.4 MPa and sprayed into the fluidized bed coating machine. After spraying, the mixture was dried until the moisture content was below 3%, forming a 120 μm thick rapid-release initiation layer on the PHA-based sustained-release layer. This yielded a PHA-based drug-fertilizer-molasses composite rapid-release sustained-release formulation.

[0043] Example 7 This embodiment provides a PHA-based pesticide-fertilizer-molasses compound fast-release formulation suitable for insecticidal purposes in vegetable fields. The difference between this and Example 6 is that both the core pesticide component and the outer pesticide component are imidacloprid.

[0044] Example 8 The difference between this embodiment and Embodiment 6 is that the HMC-modified kaolin used is replaced by an equal amount of kaolin.

[0045] Example 9 The difference between this embodiment and Embodiment 6 is that, in the preparation of the HMC-modified kaolin, step 2 is omitted, and the pretreated kaolin prepared in step 1 is used instead of the activated kaolin used in step 3.

[0046] Performance testing: The PHA-based drug molasses compound rapid-release formulation prepared in Examples 4-6 and 8-9 was administered at a dose of 60-70 g / m³. 2 The appropriate amount of fertilizer was applied to corn in the field, and field experiment management was carried out in accordance with the standard NY / T 3181-2018 "Technical Specification for Field Evaluation of Fertilizer Efficacy of Slow-Release Fertilizers"; According to the standard GB / T 17980.42-2000 "Field Efficacy Test Guidelines for Pesticides (I) Herbicides for the Control of Weeds in Corn Fields", the control effect of herbicides on weeds such as crabgrass and nutgrass in corn fields was measured and statistically analyzed 5 days after application. The nutrient release period of the PHA-based fertilizer molasses compound fast-start slow-release formulations prepared in Examples 4-6 and 8-9 was determined according to the standard GB / T 23348-2009 "Slow-Release Fertilizers", and it was observed whether weeds grew in the field during the release period. A fixed number of corn plants were sampled at a fixed location. After the roots were taken, the surface soil was washed off, and the roots were dried to remove surface water. The average weight of the root systems from multiple corn plants was calculated, and then the formula was used to... Calculate the root fertilization rate, where A1 is the average weight of maize roots in the experimental field and A0 is the average weight of maize roots in the blank experimental field. The NPK nutrient utilization rate was determined according to the standard DB22 / T 2802-2017 "Technical Specification for Field Trial of Fertilizer Utilization Rate in Soil Testing and Fertilizer Recommendation for Maize"; The utilization rate of nicosulfuron was determined according to standard NY / T 3630.1-2020, "Field Determination Methods for Pesticide Utilization Rate Part 1: Determination of Pesticide Deposition Utilization Rate in Foliar Spraying of Field Crops - Allura Red Indicator Method". The specific test data is shown in Table 1 below.

[0047] Table 1 - Performance data of compound formulations in maize fields The PHA-based drug molasses compound rapid-release formulation prepared in Example 7 was administered at a dose of 40-50 g / m³. 2 The appropriate amount of fertilizer was applied to tomatoes in the field, and field experiments were conducted in accordance with the standard NY / T 3181-2018 "Technical Regulations for Field Evaluation of the Fertilizer Efficacy of Slow-Release Fertilizers". The control effect on aphids was observed and statistically analyzed after 1 day of application and the increase in fresh weight of tomato leaves after 3 days. The NPK nutrient utilization rate and imidacloprid utilization rate were also tested. The specific test data are shown in Table 2 below.

[0048] Table 2 - Performance data of compound formulations in tomato fields Data Analysis: Comparative analysis of the data in Table 1 shows that the PHA-based fertilizer-molasses compound rapid-release formulation prepared in this invention, when applied to corn planting, causes weeds such as barnyardgrass and nutgrass to wilt within 2 days of application, and achieves a weed control effect of 90.3-91.2% within 5 days; the nutrient release period reaches 45 days, and there is no weed recurrence or nutrient deficiency in the corn field throughout the nutrient release period; the root fertilization rate after application reaches 11.3-11.5%, and the utilization rate of nitrogen, phosphorus, and potassium nutrients reaches 78.6-78.9%, which is about 52% higher than that of traditional corn fertilizer; the utilization rate of nicosulfuron reaches 83.4-83.6%, which is about 45% higher than that of single spraying; after 90 days of application into the soil, the degradation rate of the compound formulation reaches 96%, with no residue in the soil, and the number of beneficial microorganisms increases by about 35%; Comparative analysis of the data in Table 2 above shows that when the PHA-based fertilizer-molasses compound fast-acting slow-release formulation prepared in this invention is applied to corn planting, the utilization rate of nitrogen, phosphorus, and potassium nutrients in the compound formulation reaches 80.3%, which is about 55% higher than that of traditional vegetable fertilizers; the utilization rate of imidacloprid reaches 85%, which is about 48% higher than that of single spraying; the aphid control effect reaches 92.4% within 1 day after application; the fresh weight of tomato leaves increases by 12.5% ​​after 3 days; and the degradation rate of the compound formulation reaches 97% after 80 days of application into the soil. The pesticide residue levels in the harvested corn and tomatoes were all below the national standard limits; The performance test data of Examples 8-9 were all inferior to those of other examples, and weed growth was observed in the field during the release period of Example 8. This indicates that the present invention improves the stability and coating integrity of bifunctional core particles by utilizing the comprehensive effects of HMC-modified kaolin in interface activation, adsorption slow release, and enhanced coating adhesion. At the same time, by leveraging the barrier effect of the PHA-based slow release layer and the rapid dissolution and release characteristics of the molasses initiation layer, the formulation can take effect quickly after application and provide a stable supply of active ingredients for a long period of time. This significantly improves pesticide utilization and nutrient absorption efficiency, prolongs the action period, reduces residue risk, and ultimately achieves a highly efficient, controllable, and environmentally friendly synergistic release effect of pesticides and fertilizers.

[0049] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A rapid-release, sustained-release formulation of a PHA-based drug compounded with molasses, characterized in that, It includes, from the inside out, the following layers: dual-function kernel particles, PHA-based slow-release layer, and fast-release initiation layer; The bifunctional core particles comprise the following components by weight: 40-50 parts of nutrients, 5-10 parts of core pesticide composition, 15-25 parts of HMC-modified kaolin, and 3-5 parts of binder. The thickness of the PHA-based sustained-release layer is 100-200 μm; The rapid release initiation layer comprises the following components by weight: 50-60 parts molasses, 8-15 parts outer pesticide composition, and 10-20 parts fast-acting nutrients, with a thickness of 60-120 μm.

2. The rapid-release, sustained-release formulation of a PHA-based drug compound with molasses according to claim 1, characterized in that, The nutrient elements are composed of urea, monoammonium phosphate, potassium sulfate, boric acid, zinc sulfate, and EDTA-iron in a weight ratio of 10-15:12-16:10-15:0.5-0.8:1-1.5:0.6-0.8; the core pesticide composition is any one or more of herbicides, fungicides, and insecticides, wherein the herbicide is one or a mixture of two of glyphosate and nicosulfuron, the fungicide is one or a mixture of two of carbendazim and pyraclostrobin, and the insecticide is one or a mixture of two of imidacloprid and chlorantraniliprole.

3. The rapid-release, sustained-release formulation of a PHA-based drug compound with molasses according to claim 1, characterized in that, The PHA-based sustained-release layer comprises the following components by weight: 65-75 parts PHA, 35-45 parts PBAT, 10-15 parts hydroxypropyl starch, and 8-10 parts montmorillonite.

4. The rapid-release, sustained-release formulation of a PHA-based drug compound with molasses according to claim 1, characterized in that, The outer pesticide layer is composed of any one or more of herbicides, fungicides, and insecticides. The herbicide is one or a mixture of two of glyphosate and nicosulfuron, the fungicide is one or a mixture of two of carbendazim and pyraclostrobin, and the insecticide is one or a mixture of two of imidacloprid and chlorantraniliprole. The fast-acting nutrient element is composed of ammonium sulfate, potassium dihydrogen phosphate, and potassium chloride in a weight ratio of 6-8:6-8:3-4.

5. The rapid-release, sustained-release formulation of a PHA-based drug compound molasses according to claim 1, characterized in that, The preparation method of HMC modified kaolin is as follows: under the protection of an inert gas atmosphere, hydroxymethyl cellulose and N,N-dimethylformamide are mixed and stirred until the system is dissolved. Propyltriethoxysilane isocyanate and activated kaolin are added to the reaction system. The reaction system is heated to 60-70℃ and kept at this temperature for 30-50 min. Alkali solution is added to the reaction system and kept at this temperature for 40-60 min. After post-treatment, HMC modified kaolin is obtained.

6. The rapid-release, sustained-release formulation of a PHA-based drug compound molasses according to claim 5, characterized in that, The ratio of hydroxymethyl cellulose, N,N-dimethylformamide, propyltriethoxysilane isocyanate, activated kaolin, and alkali solution is 3-4 g:50 mL:0.9-1.2 g:5-6 g:5 mL. The alkali solution is a 2-3 mol / L sodium hydroxide solution. The post-treatment includes: after the reaction is complete, cooling the reaction system to room temperature, adding anhydrous ethanol to the reaction system, stirring and dispersing for 30-50 min, filtering, washing the filter cake three times with 80 vol% ethanol aqueous solution, drying it, transferring the filter cake to a drying oven at 60-70℃, and drying it to constant weight to obtain HMC modified kaolin.

7. The rapid-release, sustained-release formulation of a PHA-based drug compound molasses according to claim 5, characterized in that, Activated kaolin is obtained through the following steps: A1. Mix kaolin and sulfuric acid solution, heat the reaction system to 80-90℃, keep it at the temperature and stir for 3-4 hours, and then perform post-treatment to obtain pretreated kaolin. A2. Mix the pretreated kaolin and the activation solution, heat the reaction system to 60-70℃, keep it warm and stir for 2-3 hours, and then perform post-treatment to obtain activated kaolin.

8. The rapid-release, sustained-release formulation of a PHA-based drug compound molasses according to claim 7, characterized in that, In step A1, the solid-liquid ratio of the kaolin and sulfuric acid solution is 1:3-5. The sulfuric acid solution is composed of 15-20wt% sulfuric acid and sodium dodecyl sulfate at a ratio of 50mL:1g. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, and then transferred to a drying oven at a temperature of 70-80℃. After drying to constant weight, it is ground and passed through a 200-mesh sieve to obtain pretreated kaolin. In step A2, the solid-liquid ratio of the pretreated kaolin and the activation solution is 1:8-10. The activation solution is composed of calcium chloride, magnesium chloride, and deionized water at a ratio of 2g:1g:100mL. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, and then transferred to a drying oven at a temperature of 70-80℃. After drying to constant weight, activated kaolin is obtained.

9. The rapid-release, sustained-release formulation of a PHA-based drug compound with molasses according to claim 1, characterized in that, The PHA-based drug-molasses compound rapid-release formulation was prepared by the following steps: S1. Add nutrients, pesticide components, HMC-modified kaolin and binder to a mixer and mix for 15-20 minutes to obtain a mixed base material. Add deionized water to the mixer and mix for 8-10 minutes. Then feed it into a granulator to granulate and obtain bifunctional core particles with a particle size of 2-5 mm. S2. Mix PHA, PBAT, emulsifier and ethanol, heat the reaction system to 50-60℃, stir and disperse for 20-30 min, add a mixed slurry composed of hydroxypropyl starch, montmorillonite and deionized water to the reaction system, emulsify and disperse for 40-50 min to obtain the coating solution. Mix molasses, pesticide components, fast-acting nutrients, emulsifier and deionized water, emulsify and disperse for 10-15 minutes to obtain molasses-based suspension; S3. Place the bifunctional core particles in a fluidized bed coating machine. Spray the coating solution into the fluidized bed coating machine in the form of atomization. After spraying, dry for 15-20 minutes to form a PHA-based sustained-release layer coating on the outside of the bifunctional core particles. Then, spray the molasses-based suspension into the fluidized bed coating machine in the form of atomization. After spraying, dry until the moisture content is below 3% to form a rapid-release initiation layer coating on the PHA-based sustained-release layer, thus obtaining a PHA-based drug-fertilizer-molasses composite rapid-release sustained-release formulation.

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