Mancozeb nano suspension and preparation method thereof

Abstract

Relates to a mancozeb nano-suspension with the particle size of less than 100 nanometers and a preparation method of the mancozeb nano-suspension. Two or three components are diluted and mixed with water to form the mancozeb nano-suspension with the grade of less than 100 nanometers. The preparation method comprises the following steps: under the condition that the stirring speed is not less than the effective stirring speed, adding the diluent of the component I into the diluent of the component II, or adding the diluent of the component II into the diluent of the component I to form the mancozeb nano suspension.

Description

Mancozeb nano suspension and preparation method thereof

Technical field

[0001] The invention belongs to the field of nano pesticides, and particularly relates to the preparation of nano suspensions with particle sizes less than 100 nanometers. [Background Technology]

[0002] Improving pesticide efficacy is one of the key approaches to reducing pesticide use, and developing nanopesticides is the best approach. Nanopesticides, which originated in the early 2000s, use nanotechnology to reduce the particle size in pesticide formulations and achieve nanodispersion. A nanometer (nm) is a unit of length, with 1 nm being one billionth of a meter and one millionth of a millimeter. Simply put, nanopesticides are pesticide formulations whose particle sizes are at the nanometer level during application. For both effectiveness and stability, a particle size of less than 100 nm is ideal, with smaller being the best. Currently, the particle size of traditional pesticide formulations is larger than microns. If the particle size is reduced to the corresponding nanometer size, a 1,000-fold reduction in particle size, the number of particles could theoretically increase by a billion times, and the surface area by a thousand times. This is the rationale for the development of nanopesticides.

[0003] In April 2019, on its 100th anniversary, the International Union of Pure and Applied Chemistry listed "nanopesticides" as the top of its "Top Ten Chemical Innovations That Will Change the World." Nanopesticides, based on their higher delivery efficiency and improved absorption, can address the major challenges of traditional pesticide formulations: environmental pollution, pesticide accumulation in organisms, and the significant increase in pest and disease resistance. They can significantly reduce pesticide usage. Therefore, nanopesticides have become a key development technology for the next generation of pesticide formulations.

[0004] Mancozeb has been used internationally for over 50 years, consistently in large quantities. It is a highly effective protective organosulfur fungicide. Its low toxicity, long-lasting effect, ability to kill multiple pathogens, resistance to resistance, and excellent control effectiveness have made it a favorite in the plant protection industry. The development of mancozeb fungicides has been a long journey. The fungicidal activity of mancozeb was first discovered by Hester WF. In 1943, Rohm & Haas first synthesized mancozeb, and in 1950, Rohm & Haas and DuPont jointly produced mancozeb, leading to the continued expansion of the mancozeb class. While mancozeb and mancozeb have long been produced and used in China, mancozeb is a relatively recent discovery. It effectively controls a variety of diseases in fruits, vegetables, and wheat, and is relatively safe and low in toxicity.

[0005] Mancozeb has become one of the most important mancozeb products. Its chemical name is a coordination compound of ethylenebis(dithiocarbamate)manganese (polybasic) and zinc salts. Its cyclic chemical structure is shown in Formula (1), and some believe it to be a linear structure. ISO defines it as a mixture of zinc and maneb, containing approximately 20% manganese and 2.55% zinc, present as a salt. The technical drug is a grayish-yellow powder with a melting point of 192-204°C (decomposition). Its solubility in water (pH 7.5, 25°C) is extremely low at 6.2 mg / L, and it is insoluble in most organic solvents. This solubility limits the development and application of its formulation types. It is stable under normal, dry conditions and decomposes when exposed to heat or moisture.

[0006] Dithiocarbamates primarily react with the sulfhydryl groups of amino acids and fungal enzymes, inactivating them and thus interfering with lipid metabolism, respiration, and ATP production. They are broad-spectrum, non-systemic fungicides with protective properties. They are used on a variety of crops, including fruit trees, ornamental vegetables, and tobacco. They also control a variety of important foliar fungal diseases. They are highly effective against early and late blight of potatoes and tomatoes; downy mildew and black rot of grapes; web blotch, streak, and large leaf spot of wheat and corn; damping-off and seedling spot of cotton and peanuts; downy mildew, anthracnose, and blight of vegetables.

[0007] Mancozeb can be combined with a variety of pesticides to form a variety of compound preparations. However, whether used alone or in combination, due to its physical properties - it is insoluble in water and organic solvents - its main dosage forms are traditional powders, wettable powders, water-dispersible granules, and suspensions. According to the existing level of pesticide preparation processing technology, the minimum size of pesticide particles in its preparations is usually more than a few microns, and the largest ones are more than ten microns or even dozens of microns. The large size of mancozeb pesticide particles is not conducive to the efficacy of the drug. In addition, a certain degree of drug resistance has been generated by years of large-scale use. The current usage per unit area is large, usually 750g to 2250g of active ingredient / hm2. 2 So, how to improve its efficacy and reduce its dosage per unit area?

[0008] It should be made clear that the preparation of several existing mancozeb pesticide formulations is based on the synthesis of the technical drug first and then the processing of various formulations. The specific steps include: (1) Technical drug synthesis. It is divided into two steps: the first step is to synthesize mancozeb or mancozeb sodium, and the second step is to synthesize mancozeb. The synthesized mancozeb or mancozeb sodium is water-soluble and can be dissolved in water. Then, it is subjected to salt formation and complexation reaction with manganese salt and zinc salt respectively to obtain block precipitated mancozeb. The precipitated mancozeb is neither soluble in water nor in organic solvents, and needs to be separated, washed, and dried to obtain mancozeb technical drug. (2) Preparation processing. The preparation is processed using solid mancozeb technical drug as raw material. Usually, crushing, grinding, mixing and other processing are required to obtain mancozeb preparations. The above preparation process after mancozeb or mancozeb requires the addition of corresponding production equipment and workshops, such as filters, dryers, crushers, grinders, mixers, and corresponding production processes and processing technology. It can be found that the process from synthesizing water-soluble mancozeb or mancozeb to processing it into different dosage forms of mancozeb is both long and energy-consuming.

[0009] The traditional process flow for preparing mancozeb technical and processing it into the most common dust and wettable powder is shown in Figure 1.

[0010] [Summary of the invention]

[0011] Prior application: PCT / CN2022 / 139831

[0012] One of the purposes of the above invention is to overcome the shortcomings of the prior art and provide a new idea and method for preparing a mancozeb powder dosage form that is different from the prior art. Through the dilution process with water, mancozeb (or mancozeb, mancozeb potassium) reacts with mancozeb salt and zinc salt to produce mancozeb, thereby providing a water-soluble and transparent mancozeb nanosuspension that can be directly used for spraying.

[0013] The mancozeb nano suspension of the above invention can be loaded into a pesticide spraying device for spraying.

[0014] Mancozeb is a water-soluble ammonium salt, dispersed as a single molecule in water, serving as one component. Manganese and zinc salts, which react with it, are also dispersed as single molecules and metal ions in water, serving as the other component. When these two react, they easily form a mancozeb and zinc salt structure. Because manganese and zinc ions are both polyvalent metal ions, the resulting mancozeb is actually a complex structure, in addition to the commonly assumed salt formation. Due to the rapid salt formation and complexation reactions, mancozeb nanocrystals can be formed by controlling the amount of one component added at the beginning of mixing.

[0015] Under controlled stirring conditions, an aqueous solution of one component (e.g., a manganese salt or zinc salt) is added to an aqueous solution of another component (e.g., mancozeb). By controlling the addition rate and stirring speed, mancozeb nanoparticles can be generated, forming a mancozeb nanosuspension.

[0016] The generated mancozeb nanoparticles, when very small in size and few in number, can temporarily and stably exist in water. As mancozeb nanoparticles are continuously generated, collisions, growth, and aggregation of mancozeb nanoparticles will occur in the system. When the size of the mancozeb nanoparticles approaches the wavelength of visible light, or even exceeds it, the system begins to show opalescence and gradually becomes opaque. Coupled with the effect of the grains' own gravity, large-sized grains are precipitated. In order to prevent this phenomenon, polymer additives must be added to the system. Polymer additives are water-soluble polymers, usually non-crystalline polymers. After dissolving in water, they exist in the form of random coils. Random coils are loose spherical structures formed by the spontaneous curling of water-soluble polymer chains. The internal structure is composed of lipophilic and hydrophobic molecular main chains, while the external structure is composed of hydrophilic polar groups. At this point, when the mancozeb nanoparticles generated by the system are less than 100 nanometers in size, the shear forces of mechanical stirring cause these water-insoluble mancozeb nanoparticles to disperse into the interior of the random coils, where they are loaded by the random coils, isolating and preventing further effective collision, crystallization, growth, precipitation, and settling of the crystals. Therefore, the random coils formed by the water-soluble polymer additive disperse, suspend, stabilize, and protect the mancozeb nanoparticles. Because the random coils are uniformly dispersed in the aqueous phase, the mancozeb nanoparticles uniformly dispersed within the random coils are also uniformly dispersed in the aqueous phase. When the crystal size is below 100 nanometers, according to the Tyndall phenomenon, natural light passing through the solution is not significantly reflected or refracted, resulting in the system appearing clear and transparent and apparently water-soluble.

[0017] It's important to note that during the nanopesticide crystal formation process, the addition rate of the miscible active ingredient solution and the stirring speed of the composite adjuvant solution affect the amount of solution added to the aqueous phase per unit time and the uniformity of its dispersion, making them crucial factors influencing the size of the resulting nanopesticide crystals. Regarding the addition rate, if the target size of the precipitated nanopesticide crystals is less than 100 nanometers, the clarity and transparency of the system is the key criterion. This is based on the theory that when the particle size is less than one-quarter of the lower limit of the visible light wavelength, significant refraction and reflection are avoided, and the system is therefore transparent. The wavelength of visible light ranges from 400 to 760 nanometers, and less than one-quarter is less than 100 nanometers. Conversely, if the system producing nanopesticide crystals is clear and transparent, it indicates that the resulting crystals are less than 100 nanometers in size.

[0018] To achieve this goal, the following points must be focused on:

[0019] ① The mixing speed of the two-component solution (i.e., the speed at which one component is added) should not be too fast. If the solution is added too quickly, the two components will be unevenly dispersed, leading to excessively high local concentrations. This will accelerate the formation of crystals, resulting in a large number of crystals. This can lead to aggregation between nanocrystals, which in turn increases the size of the crystals. If the system exhibits opalescence, it indicates that the crystals are already several hundred nanometers in size. Increasing opalescence, even to the point of opacity, indicates that the crystals are approaching or exceeding one micron in size. Therefore, the addition speed should be adjusted to maintain the system's transparency.

[0020] ② The stirring speed of the system should be appropriately increased. The stirring speed of the system is related to the formation and dispersion rate of nanopesticide crystals in the aqueous phase. The more thorough the stirring and the better the dispersion, the more conducive it is to the rapid formation and dispersion of nanoparticles, keeping smaller crystals in a stable dispersed state and preventing aggregation between crystals. Only in this way can small and uniform mancozeb nanoparticles be obtained. When the two-component solution is added, it is necessary to continue stirring for a while to ensure the dispersion, suspension, and stability of the generated mancozeb nanoparticles in the water-soluble polymer additive.

[0021] Explanation of terms

[0022] Tyndall effect: When a beam of light passes through a colloid, a bright "pathway" can be observed perpendicular to the incident light. This phenomenon, also known as the Tyndall effect, is essentially the scattering of light when propagating through a colloid. This phenomenon occurs primarily because the particle size of colloidal particles ranges from 1 to 100 nm, resulting in significant scattering of visible light when passing through a colloid, while true solutions exhibit very little scattering of light. Therefore, colloids exhibit a pronounced Tyndall effect, while true solutions with dispersed molecules exhibit almost no scattering. Consequently, the Tyndall effect is often used to distinguish colloidal solutions from true solutions.

[0023] A further explanation of the Tyndall effect is that when propagating light strikes particles in a solution, if the particles are larger than the wavelength of the incident light (400nm to 740nm) or many times larger, significant light reflection occurs. If the particles are smaller than the wavelength of the incident light, light scattering occurs, with the observed light waves radiating outward around the particles. This diffuse light is called scattered light or opalescence. The Tyndall effect is essentially a phenomenon of light scattering, or opalescence. Since the radius of particles in a true solution generally does not exceed 1nm, colloidal particles are intermediate between solute particles and turbidity particles in a solution, with a particle size of 1 to 100nm. This is less than one-quarter of the lower limit of the visible light wavelength. Therefore, visible light will be significantly scattered when passing through colloids. However, since the molecules or ions in a true solution are even smaller, the intensity of the scattered light decreases significantly as the volume of the scattering particles decreases. Therefore, the scattering effect of true solutions on light is very weak. Furthermore, the intensity of scattered light increases with increasing particle concentration in the dispersed system. From this we can judge: when the observed solution is clear and transparent, it indicates that the particle size in the solution is less than 100nm, and the Tyndall phenomenon may occur; when the observed solution shows opalescence or the opalescence becomes increasingly heavier, it indicates that the particle size is greater than 100nm, and the particle size tends to become larger and larger; when the solution is turbid or even opaque, the particle size has increased to microns or above.

[0024] System: The so-called system refers to the suspension system formed by mixing the two components while controlling the addition rate and stirring when preparing the mancozeb nanosuspension in the present invention. The system is the target product—the nanosuspension—formed by mixing water, a precursor, a zinc salt, a manganese salt, and a water-soluble polymer additive.

[0025] Component: A component is a composition comprising one or more ingredients. In principle, any ingredient used in this invention can constitute a component on its own. However, for ease of packaging, transportation, and use, the components should be simplified. The principles are: 1) the ingredients should not react with each other; 2) the number of components should not be too large.

[0026] Ingredients: The so-called ingredients refer to the raw materials used in the present invention, including water-soluble mancozeb salt, zinc salt, manganese salt, water-soluble polymer additives and water.

[0027] Precursor: The so-called precursor refers to the parent substance used in the reaction to produce the target product maneb, that is, water-soluble maneb salts, including maneb, maneb sodium and maneb potassium.

[0028] Water-soluble polymer additives are macromolecular substances containing hydrophilic polar groups that are soluble in water. They are also called polymer surfactants or active agents. Water-soluble polymer additives can provide dispersion, suspension, emulsification, and stabilization. Based on the nature of the groups, they can be categorized as anionic, cationic, zwitterionic, and nonionic polymer additives.

[0029] Particle size: also known as particle size; refers to the size of the mancozeb crystals formed by the interaction of the precursor with manganese salts and zinc salts under the dispersion of water-soluble polymer additives in the system. It also includes the particle size formed by other pesticide varieties compounded with it, and does not specifically refer to the microscopic morphological structure of the crystals.

[0030] Sub-100 nanometers: This is a statistical classification of pesticide particle sizes within a system. All pesticide particle sizes within a suspension exhibit a statistical distribution. Sub-100 nanometer nanosuspensions, as described herein, refer to suspensions where the peak value on the particle size distribution curve between the mass fraction of each fraction and its corresponding size is less than 100 nanometers. Measurements can be made using a Malvern laser nanoparticle size analyzer (UK), using the Number Statistical Method.

[0031] Stability period: This refers to the time that the nanosuspension remains transparent after preparation. To ensure the completion of the spraying operation, the stability period should be no less than 1 hour. The present invention proposes an hourly stability period, which means a stability period of between 1 and 10 hours.

[0032] Effective stirring speed: The so-called effective stirring speed refers to the ability, under a certain addition method, to disperse the nanocrystals generated in the system promptly when one component is added to another, by stirring at a speed no less than the effective stirring speed, preventing grain growth and aggregation, and preventing the grain size from increasing to several hundred nanometers. Transparency of the resulting solution is a sign of effective stirring.

[0033] Effective stirring: The addition of components and the stirring method and speed have a significant impact on the resulting liquid. Stirring methods include mechanical stirring, multi-point mechanical stirring, manual stirring, and multi-point manual stirring. Fast stirring speeds are associated with optimal results. If the resulting liquid is transparent, the stirring is considered effective. Otherwise, the stirring is considered ineffective.

[0034] Addition method: The so-called addition method includes adding component A to component B, component B to component A, or adding component A and component B to the system simultaneously. It also includes continuous addition, intermittent addition, trickle addition, dropwise addition, spray addition, and addition at a fixed position or a movable position. The best addition method is to mix and disperse the two components as quickly as possible.

[0035] Addition speed: After determining the addition method, control the amount of components added with the goal of achieving effective stirring.

[0036] Nanoemulsions, also known as nanoemulsions, are solutions of pesticide active ingredients dispersed in water with the help of additives to form nanosized latex particles. Nanoemulsions are clear and transparent, with particle sizes typically below 100 nm and thermodynamic stability.

[0037] One of the objectives of the present invention is to overcome the shortcomings of the existing technology and provide a new idea and method. By utilizing the process in which pesticide formulations are usually diluted with water when spraying using water as a dispersion medium, the present invention achieves a reaction between mancozeb (or mancozeb, mancozeb potassium) and manganese sulfate and zinc sulfate to produce mancozeb, thereby providing a water-soluble and transparent mancozeb nanosuspension that can be directly used for spraying.

[0038] The mancozeb nanosuspension described in this invention can be loaded into pesticide spraying equipment for immediate application. It primarily controls downy mildew, black rot, red fire, and gray mold on grapes; scab and brown rot on apples and pears; leaf spot on stone fruits; wilt, phytophthora, downy mildew, Septoria leaf spot, and leaf mold on tomatoes; wilt and phytophthora on potatoes; downy mildew on tobacco; rust and leaf spot on ornamental plants; and rust, leaf spot, and downy mildew on vegetables. It can also be used on citrus trees, berry trees, tea trees, and rice. At the recommended dosage, it is safe for crops, including sensitive crops during their growth stages.

[0039] The mancozeb nanosuspension of the present invention refers to a mancozeb nanosuspension with a size of less than 100 nanometers. The mancozeb nanosuspension with a size of less than 100 nanometers is formed by diluting and mixing at least two components with water:

[0040] Component A: water-soluble maneb salt or water-soluble maneb salt aqueous solution, water-soluble polymer additive; the water-soluble maneb salt is one of maneb ammonium, maneb sodium, and maneb potassium, or a mixture of at least two of them;

[0041] Component B: manganese salt, zinc salt, or an aqueous solution of manganese salt and zinc salt in a certain mass ratio;

[0042] The component B may be further added with a water-soluble polymer auxiliary agent to form an aqueous solution.

[0043] The water-soluble polymer auxiliary agent is a nonionic surfactant.

[0044] The ratio of the amount of the water-soluble polymer additive to the amount of dilution water is no greater than 1:1500, preferably no greater than 1:1200, and more preferably no greater than 1:1000. The amount of dilution water includes all the water in the system.

[0045] Nonionic surfactants may include water-soluble starch and its derivatives, water-soluble guar gum and its derivatives, polyoxypropylene-polyoxyethylene block copolymers, alkylaryl polyoxypropylene polyoxyethylene ethers, fatty alcohol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, fatty amine polyoxyethylene ethers, castor oil polyoxyethylene ethers, Tween, alkyl polysaccharides, polyvinyl alcohol, polyvinyl pyrrolidone, etc. Preferably, polyoxypropylene-polyoxyethylene block copolymers, alkylaryl polyoxypropylene polyoxyethylene ethers, OP-10, fatty alcohol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, castor oil polyoxyethylene ethers, Tween, alkyl polysaccharides, etc.

[0046] The manganese salt is selected from at least one of manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate; the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, and zinc nitrate.

[0047] Furthermore, the mancozeb nanosuspension with a size of less than 100 nanometers has a stable period of hours.

[0048] When mancozeb, manganese salt and zinc salt are mancozeb, manganese sulfate and zinc sulfate respectively, the range of their mass ratio is:

[0049] Mancozeb (producing 100 mass%): manganese sulfate: zinc sulfate = 90: 41-55: 7-17

[0050] Preferably, mancozeb: manganese sulfate: zinc sulfate = 90: 41-43: 7-9

[0051] Furthermore, mancozeb: manganese sulfate: zinc sulfate = 90:41:7

[0052] When the mass ratio of the three is mancozeb (generating 100 mass of mancozeb): manganese sulfate: zinc sulfate = 90:41:7, the mass of the water-soluble polymer additive added to component B, which dissolves the manganese salt and zinc salt in as little water as possible, is preferably such that no turbidity occurs, and is usually not more than 5%.

[0053] Mancozeb suspension below 100nm

[0054] In order to improve the efficacy of nano-scale mancozeb, the present invention needs to reduce its particle size as much as possible. The original intention of studying nanopesticides is to improve the efficacy of pesticides and reduce the amount of pesticides used. The particle size of traditional pesticide preparations is usually in the micron level. Reducing it to the corresponding nanometer size spans three orders of magnitude. When reducing it to different orders of magnitude, the number of particles increased is also different. For example, if the particle size of traditional preparations is reduced from 2μm to 200nm, 20nm, and 2nm respectively, theoretically, the number of particles will increase by 1000 (10 3 ), 1 million (10 6 ), 1 billion (10 9) times. Therefore, it can be seen that different reductions in particle size and increases in particle number lead to different effects on the efficacy of the drug. Therefore, in order to improve the efficacy of nanopesticides, the particle size should be reduced as much as possible.

[0055] To further enhance the efficacy of nano-scale mancozeb, the present invention aims to reduce its particle size to below 100 nm. This is based on two factors. First, a size below 100 nm is the minimum size required for nanomaterials in any one dimension. Second, pesticide particles between 1 and 100 nm form a colloidal solution, appearing water-soluble and clear. When a beam of light is shone upon the solution, a well-defined beam of light is observed, consistent with the description of the Tyndall phenomenon.

[0056] Concentration of suspension

[0057] In suspensions with low active ingredient concentrations, the number of particles below 100 nm is relatively high, which has little effect on transparency. This is the case for a system with a mancozeb dosage of 1500 g / ha and a dilution of more than 50 kg of water.

[0058] In suspensions with high active ingredient concentrations, the number of particles smaller than 100 nanometers is relatively low, significantly impacting transparency. For a system with a mancozeb dosage of 1500 grams per hectare diluted with 20 kilograms of water, while the suspension may briefly become transparent, the high active ingredient concentration makes the particles more likely to collide with each other, leading to crystal growth and aggregation, significantly affecting the suspension's transparency stability.

[0059] The situation where the water consumption is between 20 and 50 kg is the transition period of the suspension concentration.

[0060] Stable period

[0061] The mancozeb nano suspension prepared by the present invention is a colloidal solution that is transparent in appearance and appears water-soluble, but it is not a thermodynamically stable system. Therefore, the time for some nano mancozeb suspensions to remain transparent is not infinite, but rather there is a stable period. Considering the operating characteristics of the spraying operation, after the nano mancozeb suspension is prepared, the required operating time should be at least more than 1 hour, so the length of the stable period can be described in hours. Therefore, the present invention proposes the concept of a "stable period" for nano-mancozeb suspensions below 100nm. That is, the mancozeb suspensions below 100nm prepared by the present invention can complete the spraying operation within the period when the solution remains transparent, and the stable period should reach at least 1 hour.

[0062] From the application perspective, the stable period can be further divided into four time periods: less than 1 hour, 1 to 5 hours, 5 to 10 hours, and more than 10 hours.

[0063] The spraying operation was completed within 1 hour, indicating that the nano-mancozeb suspension still maintained a transparent state, that is, the particle size was ensured to be still less than 100 nm.

[0064] Direct observation can be used to determine changes in the transparency and particle size of nanoscale mancozeb suspensions. During the stable period, the suspension remains transparent, with particle sizes less than 100 nm. When the suspension becomes unstable, opalescence initially appears, indicating that the particles are beginning to increase in size. A faint opalescence indicates that the particles are beginning to exceed 100 nm. Increasing opalescence indicates that the particles have increased in size to several hundred nanometers. Further turbidity or even opacity indicates that the particles have increased in size to the micrometer level or above. Crystallization or precipitation indicates that the particles have reached the millimeter level.

[0065] The present invention is applicable to the observation of the phenomenon of the stable period of the mancozeb suspension with a size below 100 nanometers at different hourly levels.

[0066] Hourly stability period

[0067] From the perspective of spraying operations:

[0068] The stabilization time is about 1 hour, which is not enough for the operation time of spraying operations; if the stabilization period exceeds 10 hours, it is not meaningful to use the spray liquid as a pesticide formulation, because even if the liquid is very stable, it is not conducive to storage and transportation due to the low content of active ingredients and large volume capacity.

[0069] Therefore, the stabilization time is between 1 and 10 hours, and the spraying operations of most pesticide equipment can be completed easily within this time.

[0070] The hour-level stabilization period mentioned in the present invention refers to a stabilization time between 1 and 10 hours.

[0071] For the hourly stable period, further detailed division can be carried out.

[0072] The basic period for spraying operation is 1 to 5 hours; in most cases, the spraying equipment can complete the operation.

[0073] 5 to 10 hours is a sufficient period for spraying operations; it can be used to accommodate spraying operations that are delayed due to special circumstances.

[0074] Components and additives of mancozeb nanosuspension

[0075] Traditional single-ingredient and binary formulations of mancozeb typically consist of only one component and can be sprayed after dilution with water. However, most pesticide particles are larger than microns in size. To produce a nano-scale mancozeb suspension, the present invention employs at least two components. By diluting the suspension with water according to a specific method, a mancozeb suspension with a particle size of less than 100 nanometers can be obtained.

[0076] Taking the three-component model as an example, the following explanation is given.

[0077] Three-component basic scheme

[0078] The basic scheme of the sub-100 nanometer mancozeb suspension of the present invention is a system formed by the mixed reaction of three components. They are:

[0079] Component A: It is composed of solid mancozeb, sodium mancozeb or potassium mancozeb or its aqueous solution, which is the precursor for generating mancozeb nanoparticles.

[0080] Component A can be mancozeb, mancozeb, mancozeb, or a mixture thereof. A single component or a mixture of two or three components can be solid, which is convenient to package and has a small packaging volume. It can be dissolved in water before use and dissolves quickly. However, an aqueous solution thereof can also be used and can be directly diluted with water to a certain volume before use.

[0081] Component B: It is composed of manganese salt, zinc salt solid or their aqueous solution in a certain proportion, which is the multivalent metal ion required to generate mancozeb nanoparticles.

[0082] In component B, the manganese salt is selected from at least one of manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate; and the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, and zinc nitrate. Component B may be in solid form, which reduces packaging volume; or in aqueous solution, which, however, is subject to solubility limitations and requires a certain volume specification.

[0083] Component C: It is composed of at least one surfactant, or its aqueous solution, which is an auxiliary agent that has the effects of dispersing, suspending and stabilizing the generated mancozeb nanoparticles.

[0084] Component C is an auxiliary agent composed of a water-soluble surfactant. The auxiliary agent serves to disperse, suspend, and stabilize the mancozeb nanoparticles generated in the system. The water-soluble surfactant can be selected from a polymeric surfactant and a small molecule surfactant. Considering that polymeric surfactants are superior to small molecule surfactants in dispersing, suspending, and stabilizing the nanoparticles, polymeric surfactants are preferred.

[0085] The ratio of the amount of water-soluble surfactant to the amount of water used for dilution is preferably not greater than 1:1000.

[0086] The polymer surfactant selected in the present invention is, in terms of surfactant type, a commonly used anionic surfactant, typically a monovalent metal salt or its ammonium salt. When an anionic surfactant in an aqueous solution encounters a polyvalent metal ion, it is displaced by the polyvalent metal ion, thereby losing its water solubility and precipitating in water. Therefore, the present invention uses a nonionic surfactant as a water-soluble polymer auxiliary agent to suspend, disperse, and stabilize the mancozeb nanoparticles generated in the system.

[0087] The water-soluble polymer additive described in the present invention is selected from nonionic surfactants. Preferred are derivatives of polyoxyethylene polymers, such as block copolymers of polyoxyethylene and polyoxypropylene, fatty alcohol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, fatty amine polyoxyethylene ethers, and vegetable oil polyoxyethylene ethers. Other additives include natural products and their derivatives, such as water-soluble starch, cellulose, nonionic chitosan derivatives, dextrin, methyl ethyl cellulose, and polyol derivatives, such as Tween and alkyl polyglycosides. Other additives include synthetic polymers, such as polyvinyl alcohol and polyvinyl pyrrolidone. The water-soluble polymer additive described in the present invention is one or more of the above-mentioned nonionic surfactants.

[0088] In order to simplify the components and make the packaging, storage, transportation and dilution with water operation simpler, the above three-component system can be combined into two components.

[0089] Two-component improvement plan

[0090] One of the improvements of the present invention is a suspension of mancozeb below 100 nanometers, which has a stable period of hours and is generated by a mixed reaction of two components. They are:

[0091] Component A: An aqueous solution consisting of mancozeb (or sodium mancozeb, potassium mancozeb), a water-soluble polymer additive, and water. This solution is composed of a precursor for forming mancozeb crystals smaller than 100 nanometers and a water-soluble polymer surfactant that disperses, suspends, and stabilizes the product.

[0092] Component B is composed of a solid mixture of a manganese salt and a zinc salt in a certain proportion, or an aqueous solution thereof, a water-soluble polymer additive, and water. The manganese salt is selected from at least one of manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate; and the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, and zinc nitrate.

[0093] Since the solubility of manganese salts and zinc salts in water is limited, in order to minimize the capacity specifications of component B, it is necessary to limit the amount of water used. In addition, the aqueous solution of manganese salts and zinc salts is also affected by the amount of additives added, which also limits the amount of water-soluble polymer additives added to component B.

[0094] This improvement plan is to distribute the water-soluble polymer additives used into components A and B. In view of several limitations of component B, there is an upper limit to the proportion of the water-soluble polymer additives in component B, unless the limitation of component B to a certain capacity is not considered.

[0095] Proportion of components for producing mancozeb

[0096] The above two-component improvement solution includes two components:

[0097] Component A: Use solid maneb ammonium (or sodium maneb, potassium maneb) or aqueous solution of maneb ammonium (sodium maneb, potassium maneb), and then add auxiliary agents.

[0098] Component B: a solid mixture of manganese sulfate (or manganese acetate, manganese chloride, manganese nitrate) and zinc sulfate (or zinc acetate, zinc chloride, zinc nitrate) in a certain proportion, or a solution thereof dissolved in water; an auxiliary agent may be added.

[0099] In component A and component B, the amount of active ingredients used is the basis for determining the composition of the two components. Mancozeb (or sodium mancozeb, potassium mancozeb) in component A is the precursor for the formation of nano-mancozeb and is the basis for determining the composition of component B.

[0100] The present invention takes the example of spraying 100 grams of mancozeb on 1 / 15 hectare of land, and designs two components based on the generation of 100 grams of mancozeb nano suspension with a size below 100 nm.

[0101] Component A requires approximately 90 grams of maneb or maneb, preferably maneb, as a precursor. Based on the aforementioned principle for distributing additives between Component A and Component B, the vast majority of the additives will be distributed in Component A. If both Component A and Component B are packaged in 500-gram quantities, the amount of water used is the amount after removing the maneb and additives.

[0102] For component B, first determine the amounts of inorganic manganese salt and zinc salt required for the reaction with maneb. Manganese sulfate and zinc sulfate are preferred in the present invention. It is generally believed that manganese ions react with maneb to displace ammonium ions and form salts, generating a maneb ring structure or linear polymer structure. Zinc ions can also react with maneb to form salts, but they have a stronger tetravalent coordination ability, coordinating with the sulfur atoms on the maneb salt molecules to form a complex structure.

[0103] There is no strict ratio between mancozeb and manganese ions or zinc ions, but the precursor as a complexing base has the following relationship with zinc ions:

[0104] Complexing group mass: zinc ion mass = 97.335%: 2.665%

[0105] The number of manganese ion molecules: the number of zinc ion molecules = 9:1

[0106] In the present invention, when the precursor mancozeb is used at a mass of 90 g (0.346 mol, which produces 100 g of mancozeb), the zinc salt used is zinc sulfate (anhydrate), which has a mass of 56.5 g per mole. However, according to the above-mentioned proportional relationship, the actual amount of zinc sulfate used is far less than this mass.

[0107] In the present invention, when the mass of mancozeb is 90 grams, the mass of zinc sulfate used is 3 to 8 grams, preferably 4 to 7 grams; the mass of manganese sulfate used is 25 to 65 grams, preferably 35 to 55 grams. The above data are all the masses of zinc sulfate and manganese sulfate excluding crystal water.

[0108] Distribution of additives between component A and component B

[0109] Component A mainly contains mancozeb (or mancozeb, mancozeb).

[0110] Components A and B must be packaged separately because they react when mixed. If a two-component formulation is used, component A must contain an additive; otherwise, there's no place to store the additive, unless a separate additive is added as a dedicated third component. This complicates the packaging and dilution process. The addition of additives to component A requires that both maneb and the additive be water-soluble and miscible without precipitation or other instabilities. However, given the high content of maneb and the additive, their inherent viscosity makes handling difficult. Therefore, a certain amount of water must be added to dilute the mixture, reduce viscosity, and facilitate dilution. The amount of water added should minimize the overall mass of component A, while achieving these objectives, to reduce the resulting production, packaging, and transportation costs.

[0111] Component B is mainly manganese salt, zinc salt or their aqueous solution.

[0112] Component B can be a solid mixture of manganese and zinc salts, which should be dissolved in water before use. For convenience, aqueous solutions of these salts can be used. Due to their limited solubility, a certain amount of water is required. Adding or omitting additives is optional for two reasons: First, adding a large amount of additives to Component B will form a film on the surface of the mixed solution of manganese and zinc salts, additives, and water, hindering the subsequent dilution process. Second, if the amount of additives in Component A is sufficient to suspend and disperse the resulting mancozeb nanoparticles, additives can be omitted from Component B. However, if mancozeb is used for disease control in orchards with large tree canopies, the water consumption required for spraying is high, often reaching 200 kg / mu or more. If the amount of additives added to Component A is insufficient to support the dispersion and suspension of the resulting mancozeb nanoparticles in such a large dilution solution, an appropriate additive should be added to Component B to compensate for the insufficient amount of additives in the dilution solution. However, the prerequisite is that the amount of additive added to the aqueous solution of manganese salt and zinc salt must ensure that the solution remains transparent and avoid condensation and film formation on the surface of the solution during storage. The mass concentration of the added additive is generally not higher than 5%.

[0113] While both component A and component B can address these difficulties by increasing their mass, increasing the dosage and specifications of the two components will undoubtedly increase production, packaging, and transportation costs. Taking all these factors into consideration, balancing the dosage of other components and product specifications to minimize the use of other ingredients (adjuvants, water) while maintaining the desired unit mass of mancozeb is crucial.

[0114] Water-soluble polymer additives

[0115] 1) The transparent mancozeb tank mix solution is a mancozeb nano-suspension dispersion ready for direct use. A water-soluble polymeric additive with dispersing properties is added to this solution, resulting in the mancozeb being dispersed and suspended in the polymeric additive solution at nanometer scale. Because the particle size is less than 100 nanometers, the solution becomes a water-soluble mancozeb nano-suspension solution that appears transparent.

[0116] 2) The water-soluble polymer additive with dispersing effect is an important component that affects the size of the mancozeb nanoparticles generated when the two components are diluted and mixed, as well as whether they can be evenly dispersed and stably suspended.

[0117] 3) Polymeric additives are also known as polymeric surfactants, generally referring to substances with a relative molecular mass greater than 10,000 and exhibiting surface activity. Compared to small-molecule surfactants, polymeric surfactants not only reduce surface tension but also possess other special properties, such as dispersion, suspension, and viscosity enhancement. Polymeric surfactants can be classified by their source into natural polymers and their derivatives and synthetic polymers. Polymeric surfactants possess a hydrophobic chain structure and hydrophilic functional groups, either at the end or at the side, such as hydroxyl, carboxyl, carboxymethyl, sulfonic acid, sulfate, phosphoric acid, and amino groups, making them water-soluble polymers. Water-soluble natural polymers and their derivatives include starch (linear), dextrin, and its various derivatives; water-soluble starch, oxidized starch, carboxymethyl starch, modified starch; cellulose and its derivatives; carboxymethyl cellulose; hydroxyethyl hydroxypropyl cellulose; carboxymethyl chitosan; modified guar gum; tea saponin; water-soluble humic acid; and sodium lignin sulfonate. Synthetic water-soluble polymers include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polystyrene-maleic anhydride copolymer, and polyvinyl pyrrolidone. Since the backbones of synthetic water-soluble polymers are mostly carbon chains and are not easily biodegradable, for environmental reasons, water-soluble, biodegradable natural polymers and their derivatives should be selected as much as possible to minimize the impact on the ecological environment.

[0118] 4) The reason for selecting polymeric additives in the present invention is to utilize the dispersing and suspending properties of water-soluble polymers in aqueous solutions. Water-soluble polymers with molecular weights in the tens of thousands, hundreds of thousands, or even hundreds of thousands typically have linear polymer chain structures and are soluble in water. When dissolved in water, linear polymers exhibit a large aspect ratio, but they do not appear as straight chains. Instead, due to the flexibility of the molecular chains, they exhibit a coiled state, or "random coil" morphology. The hydrophilic groups in the random coils tend to face the aqueous phase, while the lipophilic chains are coiled within the random coils. The size of the random coils depends on the relative molecular weight of the polymeric additive, its concentration, and the polymer chain structure. The larger the molecular weight, the larger the volume of the random coils formed by a single molecule. The more flexible the polymer chain, the easier it is to rotate internally, and the more stretched it is in the solvent, the larger the random coils. When the concentration of water-soluble polymers is high, random coils formed by different molecules tend to aggregate, resulting in a larger volume. Generally, when the molecular weight of a water-soluble polymer is in the tens of thousands or hundreds of thousands, the resulting random coils are typically tens to hundreds of nanometers in size. If pesticide nanoparticles are generated in the system, based on the principle that similar structures dissolve (or are compatible), the lipophilic nanoparticles tend to enter the interior of the lipophilic random coils and become intercalated in different locations within the random coils. When the pesticide nanoparticles are smaller, more nanoparticles can be dispersed within the random coils. Therefore, water-soluble polymer adjuvants can disperse and stabilize the generated nanoparticles. Traditional pesticide suspension concentrates also utilize this principle, but their pesticide particles are micron-sized. Due to the large size of micron particles, suspension concentrates are generally opaque and subject to significant gravity, which can also affect their stability. When the size of pesticide particles is reduced by 2 to 3 orders of magnitude, the gravitational effect on the particles is much smaller. Using the same water-soluble polymer surfactant, a more stable suspension and dispersion system can be obtained, achieving apparent water solubility and transparent appearance of the suspension.

[0119] 5) Water-soluble polymer additives, like small molecule surfactants, are classified into different types based on the nature of the active groups contained in the macromolecular chain. They mainly include anionic polymer additives, cationic polymer additives, zwitterionic polymer additives, and non-ionic polymer additives. These polymer additives carry active groups of different properties on the side groups or main chains. For example, anionic polymer additives carry acidic groups such as carboxyl groups, sulfonic acid groups, and sulfate groups, as well as monovalent metal salts. Examples include carboxymethyl starch, carboxymethyl cellulose, lignin sulfonates, humates, polyacrylic acid, and polystyrene-maleate. Cationic polymer additives carry basic groups or salts formed with acidic groups, such as chitosan (hydrochloride) and polyacrylamide, as well as polymers containing pyridine groups on the side groups and being quaternized. Amphoteric polymer additives are polymers that contain both anionic and cationic groups in their molecular structure, such as carboxymethyl chitosan and carboxymethyl cellulose. The simplest non-ionic polymer additives are polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymers, as well as various polyoxyethylene ethers with hydrophobic groups such as fatty alcohols, fatty acids, fatty amines, alkylphenols, aromatic phenols, and oil groups, such as Peregual series, OP series, Tween series, polyol series, ricinoleic acid series, alkyl polyglycosides, etc.

[0120] 6) Of the first three types of polymeric additives, anions and zwitterions contain acidic groups and corresponding metal ions in their molecules, while cations contain basic groups. The presence of these polar groups causes the anionic polymeric additives to react with the zinc sulfate metal ions during the reaction between mancozeb and zinc sulfate, forming a water-insoluble structure that precipitates. Meanwhile, the basic groups of cationic polymeric additives can react with the acidic groups of mancozeb, potentially disrupting the formation of mancozeb. Therefore, generally speaking, anionic, cationic, and zwitterionic polymeric additives cannot be used as water-soluble polymeric additives in the present invention.

[0121] 7) The water-soluble polymer additive having a dispersing effect is used as an additive in the present invention only if it is a nonionic polymer additive. The hydrophilic groups of the nonionic polymer additive are random coils formed by polyoxyethylene ether, also known as "micelles." The outer sides of the random coils are hydrophilic, while the inner sides of the micelles are hydrophobic. The generated mancozeb nanoparticles enter the micelles, thereby achieving dispersion and stabilization.

[0122] 8) The mancozeb nanosuspension is directly produced by reacting the precursor mancozeb (either sodium or potassium) with manganese and zinc salts during the dilution process prior to use. Because the active ingredient content is at a relatively low spray concentration, approximately 1.0 to 0.5 g / kg water (for example, if the mancozeb active ingredient dosage is 100 g / mu, the sprayer uses 100 to 200 kg / mu of water, where an acre is 1 / 15 of a hectare, and the same applies hereinafter). The dispersion stability of the mancozeb nanosuspension can be adjusted by controlling the amount of polymer additives used.

[0123] The amount of polymer additive used is related to the amount of mancozeb generated by the system and the amount of dilution water used. For example, if 100g of mancozeb is used per mu and the dilution water used is 100kg, 150kg, and 200kg, the active ingredient concentrations are 0.100%, 0.067%, and 0.05%, respectively. The concentration of polymer additives should be at least 0.1% to 0.5%.

[0124] Testing has shown that the active ingredient particles in the mancozeb nanosuspension are approximately 10 to 80 nm in size. This nanosuspension remains stable for less than 8 hours, without precipitation or settling, and can be directly applied to various pesticide spraying equipment.

[0125] 9) The mancozeb nanosuspension is directly formed during the dilution process before spraying. It uses water-soluble mancozeb, mancozeb sodium, or mancozeb potassium as precursors, adds a polymer adjuvant, and forms component A. Component B is an aqueous solution of manganese salts or zinc salts, with or without a dispersant. The two components are mixed at a specific concentration and in a specific mixing pattern to produce the target nanosuspension. This solution not only eliminates the synthesis and purification process required by pesticide manufacturers to prepare mancozeb technical from mancozeb or mancozeb sodium, but also eliminates the multi-step physical processing required by pesticide formulation manufacturers to convert mancozeb technical into existing formulations, such as wettable powders. The solution proposed by the present invention can be directly applied to the plant protection sector of agricultural production, resulting in significant energy savings and environmental benefits, significantly reducing production costs, and producing a suspension dispersion with mancozeb particles less than 100 nm in size. Since the particle size is significantly smaller than all existing mancozeb solid dosage forms, the present invention can fully exert the efficacy, significantly reduce the amount of pesticide used, and play the role of reducing the amount of pesticide and increasing its efficacy. The test results on fruit trees have been confirmed.

[0126] FIG2 is a flow chart of the present invention for preparing the mancozeb nano suspension by diluting with water.

[0127] The key technologies of the present invention lie in the following aspects:

[0128] 1. The production process of nanopesticides

[0129] This innovative model and method for preparing nanosuspensions of water- and organic solvent-insoluble pesticides containing polyvalent metal ions has been proposed. Exploiting the need for dilution of pesticides with water, the precursor of the target product is mixed with the corresponding metal salt. The rapid reaction of metal ions is exploited to control the mixing and stirring speeds of the reactants, resulting in a nanosuspension with a particle size of less than 100 nanometers for direct use. This method eliminates the chemical synthesis and purification steps required by pesticide technical manufacturers to prepare mancozeb technical from mancozeb, sodium, or potassium, as well as the multi-step physical processing required by pesticide formulation manufacturers to convert mancozeb technical into current formulations such as wettable powders. This innovative research approach, preparation model, and method are the most critical technologies of this invention. This key technology is not only suitable for compounding mancozeb with other fungicides, but is also applicable to the preparation of nanosuspensions of similar pesticides.

[0130] 2. Mancozeb concentration

[0131] The concentration of mancozeb generated in the diluted water by Component A, primarily composed of mancozeb or mancozeb, and Component B, primarily composed of manganese salts or zinc salts, is controlled. Specifically, if the active ingredient, mancozeb, is used at a dosage of 100 g / mu, the concentration of mancozeb generated by the reaction of mancozeb or mancozeb with zinc sulfate is affected by the amount of water used for dilution. For example, the concentration of mancozeb or mancozeb should be controlled within the range of 0.09 to 0.045 g / kg, and the concentration of zinc sulfate should be controlled within the range of 0.07 to 0.0035 g / kg, corresponding to a water dosage of 100 to 200 kg. If the water dosage is too low, far less than 100 kg, for example, less than 20 kg, the resulting particles become larger and the dilution liquid becomes less transparent. This is because the higher the concentration of particles, the greater the probability of collisions to form larger particles, reducing stability and hindering the formation of particles smaller than 100 nm. If the water usage exceeds 200 kg, a transparent dilution solution can still be obtained, but the concentration of the dispersant in the components is significantly reduced, and the stability of the diluted solution will also deteriorate. Therefore, controlling the concentration of the final mancozeb produced, that is, controlling the amount of water used for dilution, is one of the key technologies for obtaining mancozeb nanosuspensions.

[0132] 3. Type and dosage of dispersant

[0133] Selecting the appropriate type and dosage of dispersant is another key technology for obtaining mancozeb nanoparticle suspensions. However, when mancozeb ammonium or sodium mancozeb is combined with manganese or zinc salts in water to form mancozeb nanoparticles, the dispersion effect of large amounts of water and stirring alone cannot maintain the size of the newly formed mancozeb nanoparticles. This is because the dispersed particles in water are not static; they are constantly undergoing Brownian motion and colliding with each other. These collisions lead to particle fusion, crystallization, and eventual precipitation. An effective way to prevent the size of the formed particles from increasing is to select the appropriate type and dosage of dispersant to ensure that the nanoparticles of the active ingredient are uniformly dispersed in the solution formed by the dispersant in water. These dispersants are primarily water-soluble polymers that are soluble in water. In water, these polymers exist as random coils. The size of these random coils is much larger than that of the newly formed mancozeb particles, typically ranging from several hundred nanometers to larger than one micron, depending on the molecular weight and dosage. If the mancozeb nanoparticles produced are smaller than 100 nanometers, for example, a few nanometers or a dozen nanometers, they can enter the interior of the random coils. To some extent, the random coils can prevent and slow down collisions between the particles, thereby improving the stability of the mancozeb nanoparticles. This is where the addition of a dispersant plays an important role.

[0134] However, there is a problem here. Water-soluble polymers come in different types. Can all of them be used? The present invention has conducted tests on a variety of different types of water-soluble polymers and the conclusion obtained is negative. Among the numerous anionic surfactants, cationic surfactants, and nonionic surfactants, only nonionic polymer additives can currently achieve the desired effect, such as alkyl alcohols, polyoxyethylene ethers of alkyl acids, polyoxypropylene-polyoxyethylene ethers of alkylaryls, OP-10, alkyl polyglycosides, castor oil polyoxyethylene ethers, Tween-80, etc., and only a few combinations of these have the best effect. The reason why anionic surfactants cannot be used is that the reaction mechanism of forming mancozeb during the dilution process is essentially a process in which polyvalent metal ions replace ammonium ions or sodium ions to form salts or complexes. When anionic surfactants are used as dispersants, the polyvalent metal ions are likely to react with the sodium salts of the acidic groups in the dispersant in the same manner, causing the dispersant to precipitate out from the water-soluble state along with the generated mancozeb nanoparticles, thus failing to achieve the dispersing effect. The present invention does not exclude the special case where an individual cationic surfactant is optimally combined with an appropriate anionic or nonionic surfactant to dissolve in water without precipitation.

[0135] The present invention uses the important role of water-soluble polymer auxiliary agent and is self-evident. The present invention utilizes, in the water dilution process, water-soluble mancozeb or sodium or potassium, with zinc salts such as zinc sulfate that zinc ion is provided, manganese salts such as manganese sulfate that manganese ion is provided, mix in a certain manner, through the reaction of zinc ion, manganese ion and mancozeb or sodium or potassium in the mixing process, generate the mancozeb suspension of level below 100 nanometers. In the system, if do not contain surfactant, especially do not contain water-soluble polymer auxiliary agent, the nano-crystal grains that generate will constantly collide with each other, cause crystallization to grow, gather, until macroscopic precipitation occurs. When there is the water-soluble polymer auxiliary agent of suitable kind and consumption in the system, the nano-crystal grains that generate will enter in the random coil that the water-soluble polymer auxiliary agent forms, just can stop and delay collision, crystallization to grow between the nano-crystal grains, thereby the mancozeb nano-crystal grains that generate are played to dispersion, suspension and stable effect.

[0136] The type and amount of the water-soluble polymer additive used in the present invention can be determined through experiments. The type of water-soluble polymer additive can be determined by conducting stability tests on different additives under fixed conditions and observing the effects. The additive type test includes a single dose of a water-soluble polymer additive or a compounded additive of two or more. The present invention will give examples of different types of water-soluble polymer additives in the test examples. The determination of the amount of the water-soluble polymer additive will be based on meeting the following two conditions: First, the generated mancozeb nanosuspension must be transparent in appearance and apparent water-soluble, so as to ensure that the particle size is below 100 nm; second, the stability time of this transparent nanosuspension is between 1 and 10 hours, at least between 1 and 5 hours.

[0137] For a system generated by the mixed reaction of two components, the amount of adjuvant is distributed to component A and component B. Theoretically, if there is no capacity limit for the two components, the proportion of adjuvants in component A and component B can be arbitrarily distributed; if there is a packaging capacity limit for the two components, for example, for the use of drugs in 1 / 15 hectare of field (to generate 100 grams of mancozeb), component A and component B are required to be 500 grams each. Considering that the amount of water used to dissolve manganese salts and zinc salts in component B is large, and the solubility of this inorganic salt solution in adjuvants is poor, the amount of adjuvant added to component B will be greatly limited. In this way, the amount of adjuvant distributed between the two components can be determined by the following formula: Amount of adjuvant (组分A) =Total amount of additives-amount of additives (组分B)

[0138] In the case of a fixed capacity, the amount of additives added to component B can be determined by the situation after the additives are added to component B. When the system changes from transparent to turbid, it is the upper limit of the amount of additives added to component B.

[0139] The amount of additive used in the present invention is relative to the amount of water used for dilution. The larger the amount of dilution water used, the more additive used. The ratio of additive to dilution water should be at least 1:1200, and preferably within 1:1000.

[0140] 4. Feeding method

[0141] The method of addition is also a key factor influencing the performance of mancozeb nanosuspensions. Determining the active ingredient content or concentration in the dilution solution effectively determines the water consumption. How is the dilution water distributed? How much is used in Component A and Component B? How is the dilution process handled? These factors all affect the size and stability of the mancozeb particles in the resulting dilution solution. For example, if the water consumption is 100 kg, two issues arise:

[0142] First, how to distribute the amount of water used into the two components to form component A dilution and component B dilution?

[0143] Second, how is it added? Is the component A diluent added to the component B diluent, or is the component B diluent added to the component A diluent?

[0144] These issues all relate to the concentration of reactants at the moment the two components are mixed. For example, if a diluent containing mancozeb, sodium mancozeb, or potassium mancozeb is used as Component A, and if so, the amount of dispersant, this is all related to the instantaneous concentration of the diluent containing mancozeb and zinc salts when added to the diluent of Component A. Furthermore, the presence or absence of stirring also affects the dispersion of the instantaneous product. The general principle is that a high concentration of dispersant in the precursor (substrate component) promotes the dispersion and stability of nanoparticles, while stirring and effective stirring also promote the dispersion and stability of nanoparticles.

[0145] Preparation method of mancozeb nano suspension

[0146] The present invention adopts the following technical solutions:

[0147] Under the condition that the stirring speed is not less than the effective stirring speed, the component A dilution is added to the component B dilution, or the component B dilution is added to the component A dilution to form a mancozeb nano suspension.

[0148] The component A diluent and the component B diluent are aqueous solutions formed by diluting the following components A and B with water respectively;

[0149] Component A: water-soluble maneb salt or water-soluble maneb salt aqueous solution, water-soluble polymer additive; the water-soluble maneb salt is one of maneb ammonium, maneb sodium, and maneb potassium, or a mixture of at least two of them;

[0150] Component B: a solid mixture of manganese salt and zinc salt in a certain proportion or their aqueous solution.

[0151] The adding method, adding speed and stirring speed are controlled so that 100 nanometer mancozeb nanoparticles are generated in the suspension, that is, 100 nanometer mancozeb nanosuspension.

[0152] Effective stirring speed

[0153] The so-called effective stirring speed refers to the process in which when one component is added to another component, the nanopesticide crystals generated in the mixed liquid can be dispersed in time by stirring at a speed not less than the effective stirring speed, without significant crystal aggregation, thus preventing the size of these crystals from increasing to hundreds of nanometers or micrometers.

[0154] Stirring method

[0155] Manual stirring: This is more suitable for most application scenarios; in this case, the stirring speed must meet the physiological requirements of manual stirring and cannot be too fast.

[0156] Mechanical stirring: In the field, it is difficult to have large containers equipped with stirring devices. If such conditions are available, the speed of large stirring equipment generally does not exceed 100 rpm. Mixing at a speed close to this is sufficient.

[0157] For manual stirring, the stirring speed should be consistent with the human body's physiological function. To obtain a stable target product, the material addition rate can be appropriately reduced. The material addition rate can be determined by observing the product's transparent state in the system.

[0158] Joining method and joining speed

[0159] To ensure that the added materials are uniformly fine and quickly dispersed upon entering the system, one component can be added to another continuously, intermittently, or dropwise. For dropwise addition, spraying with a manual sprayer, commonly available in rural areas, is the most effective method. The addition speed is determined by observing the transparency of the product within the system.

[0160] Traditional pesticide formulations sprayed with water as the dispersion medium typically require dilution or mixing of co-use pesticide formulations before spraying, a process commonly known as "tank mixing." The present invention utilizes this process to mix components A and B at specific concentrations, addition methods, and speeds in the presence of a specific adjuvant—a dispersant—to directly produce a transparent, tank-mixed mancozeb nanosuspension suitable for on-site spraying.

[0161] Dilution water consumption

[0162] Current experimental data shows that more than 20 kilograms is a reasonable starting range

[0163] Of course, this dilution water consumption is strongly related to our target stabilization period.

[0164] This is a multivariate problem, and the additives (composition, content) in the component may also have an impact.

[0165] The present invention aims to produce a mancozeb suspension with a transparency stability period of 1 to 10 hours at a level below 100 nanometers. When the unit mass of the precursor (e.g., 90 grams of mancozeb) and the metal salt (manganese sulfate or zinc sulfate) reacting with it is fixed, factors that can affect the nanometer size and stability of the particles include the amount of dilution water, the amount of additives used, and the preparation method.

[0166] The amount of water used for dilution can affect the size and stability of the resulting nano-mancozeb crystals. This is because the amount of water used as the dispersion medium affects the concentration of the mancozeb and zinc sulfate solutions at the moment of contact, as well as the uniformity of dispersion. Consequently, this influences the resulting crystal size, the effectiveness of grain dispersion, and the chances of crystal aggregation and growth. The amount of additive used affects its concentration in aqueous solutions at different water levels, as well as the extent and duration of its dispersion, suspension, and stabilization of the resulting nano-crystals. Too little water will reach a limit. For example, when the dilution water amount is below 20 kg, the stability time of the resulting transparent mancozeb nanosuspension is approximately one hour, which is insufficient for spraying operations. Therefore, the dilution water amount should be increased.

[0167] The present invention selects the dilution water amount to be between 30 and 300 kilograms, preferably in the range of 50 to 200 kilograms, for generating 100 grams of the target product, i.e., a mancozeb suspension with a transparent stability period of 1 to 10 hours at a level below 100 nanometers.

[0168] [Brief Description of the Figures]

[0169] Figure 1: a flow chart of the traditional process for preparing mancozeb technical and processing it into a wettable powder formulation;

[0170] Figure 2: Schematic diagram of the process for preparing mancozeb nanosuspension (two components)

[0171] Figure 3: Schematic diagram of the process for preparing mancozeb nanosuspension (three components)

[0172] [Implementation Method]

[0173] The method of the present invention for preparing a transparent mancozeb suspension of less than 100 nm in size comprises the following steps:

[0174] In the first step, component A and component B are diluted separately according to different water amounts and different dilution ratios to form component A dilution liquid and component B dilution liquid.

[0175] In the second step, under mechanical stirring (preferably) or manual stirring conditions, the stirring speed is not less than the effective stirring speed, and the diluted solution of component A is evenly added to the diluted solution of component B according to a certain addition method (continuous or intermittent pouring, dropwise addition, spraying, etc.); or the addition can be done in the reverse order.

[0176] The steps for the three-component protocol are as follows:

[0177] In the first step, component A (or component C) and component B are diluted respectively according to different water amounts and different dilution ratios to form component A (or component C) dilution liquid and component B dilution liquid.

[0178] The second step is to add component C (or component A) into the dilution of component A (or component C), stir and disperse evenly to form a mixed dilution of component A (component C) and component C (component A).

[0179] The third step is to uniformly add the component B dilution to the mixed dilution of component A and component C in a certain addition method (continuous or intermittent pouring, dropwise addition, spraying, etc.) under mechanical stirring (preferably) or manual stirring conditions at a stirring speed not less than the effective stirring speed; or add in the reverse order.

[0180] Here are some examples:

[0181] Example 1

[0182] Mancozeb nanosuspension can be used to control early blight in potatoes. The active ingredient dosage is approximately 100 grams per mu (approximately 100 hectares), and the dilution water requirement is typically 30 kilograms. 90 grams of mancozeb are required to produce 100 grams of mancozeb.

[0183] Component ratio: The component ratio, dilution water volume, water distribution, addition sequence and method, and test results of each component are listed in the following table:

[0184] How to do it:

[0185] Dilute and dissolve component A and component B in a ratio of 4 / 5 and 1 / 5, respectively, based on 30 kg of water. While stirring, add the diluted component B solution to the diluted component A solution in a continuous stream to obtain a transparent mancozeb nanosuspension. Stable for 3 hours.

[0186] Example 2

[0187] Mancozeb nanosuspension can be used to control leaf spot, anthracnose, and ring rot in apple trees. The active ingredient dosage is 100 grams per mu, and the dilution water requirement is generally 200 kilograms. 90 grams of mancozeb are required to produce 100 grams of mancozeb.

[0188] Component ratio: The component ratio, dilution water volume, water distribution, addition sequence and method, and test results of each component are listed in the following table:

[0189] How to do it:

[0190] Component A and component B were diluted and dissolved in a ratio of 2 / 3 and 1 / 3 of 200 kg of dilution water, respectively. While stirring, the diluted component B solution was added to the diluted component A solution by continuous spraying to obtain a transparent mancozeb nanosuspension with a stable time of 5 hours.

[0191] Example 3

[0192] Mancozeb nanosuspension can be used to control scab in pear trees. The dosage of active ingredient is 200 g / mu, and the dilution water requirement is generally 300 kg. To produce 200 g of mancozeb, 180 g of mancozeb is required.

[0193] Component ratio: The component ratio, dilution water volume, water distribution, addition sequence and method, and test results of each component are listed in the following table:

[0194] How to do it:

[0195] Component C and component B were diluted and dissolved in a ratio of 4 / 5 and 1 / 5 of 300 kg of dilution water, respectively, to produce a component C dilution solution and a component B dilution solution, respectively. Component A was then added to the component C dilution solution and stirred to disperse uniformly, forming a mixed dilution solution of components C and A. While stirring, the component B dilution solution was continuously sprayed into the mixed dilution solution of components C and A to produce a transparent mancozeb nanosuspension with a stable time of 4 hours.

[0196] Example 4

[0197] Mancozeb nanosuspension can be used to control tobacco scab. The active ingredient dosage is about 100 grams per mu, and the dilution water requirement is generally 25 kilograms. 90 grams of mancozeb are required to produce 100 grams of mancozeb.

[0198] Component ratio: The component ratio, dilution water volume, water distribution, addition sequence and method, and test results of each component are listed in the following table:

[0199] How to do it:

[0200] Dilute and dissolve component A and component B in 25 kg of water at a ratio of 4 / 5 and 1 / 5, respectively. While stirring, add the diluted component B to the diluted component A by intermittent spraying to obtain a transparent mancozeb nanosuspension. The suspension stabilizes for 2.5 hours.

[0201] Example 5

[0202] Mancozeb nanosuspension can be used to control early blight in tomatoes. The active ingredient dosage is about 70 grams per mu, and the dilution water requirement is generally 30 kilograms. To produce 70 grams of mancozeb, 63 grams of mancozeb are required.

[0203] Component ratio: The component ratio, dilution water volume, water distribution, addition sequence and method, and test results of each component are listed in the following table:

[0204] How to do it:

[0205] Dilute and dissolve component A and component B in 30 kg of water at a ratio of 2 / 3 and 1 / 3, respectively. Add the diluted component B solution dropwise to the diluted component A solution while stirring. This yields a transparent mancozeb nanosuspension. The suspension remains stable for 3.5 hours.

Claims

1. A mancozeb nanosuspension, characterized in that: The mancozeb nano suspension is a mancozeb nano suspension with a size of less than 100 nanometers. The mancozeb nano suspension with a size of less than 100 nanometers is formed by diluting and mixing two components with water: Component A: water-soluble maneb salt or water-soluble maneb salt aqueous solution, water-soluble polymer additive; the water-soluble maneb salt is one of maneb ammonium, maneb sodium, maneb potassium, or a mixture of at least two water-soluble maneb salts; Component B: a mixture of manganese salt and zinc salt in a certain proportion, or an aqueous solution thereof.

2. The Mancozeb nanosuspension according to claim 1, wherein The mancozeb nano-suspension with a size of less than 100 nanometers has a stable period of hours.

3. The mancozeb nano suspension according to claim 1, wherein The component B is added with a water-soluble polymer auxiliary agent and water to form an aqueous solution.

4. The Mancozeb nanosuspension according to claim 1, wherein The water-soluble polymer auxiliary agent is a nonionic surfactant.

5. The Mancozeb nanosuspension according to claim 1, wherein The ratio of the amount of the water-soluble polymer additive to the amount of water used for dilution is not greater than 1:1200.

6. The mancozeb nanosuspension according to claim 4, wherein The nonionic surfactant is at least one of the following options: Water-soluble starch and its derivatives, water-soluble guar gum and its derivatives, polyoxypropylene-polyoxyethylene block copolymers, alkylaryl polyoxypropylene polyoxyethylene ether, fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ether, fatty amine polyoxyethylene ether, castor oil polyoxyethylene ether, Tween, alkyl polysaccharide, polyvinyl alcohol, polyvinyl pyrrolidone.

7. The mancozeb nanosuspension according to any one of claims 1 to 6, characterized in that The manganese salt is selected from at least one of manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate; the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, and zinc nitrate.

8. The Mancozeb nanosuspension according to claim 7, wherein When the manganese salt, manganese salt and zinc salt are manganese sulfate, manganese sulfate and zinc sulfate respectively, the mass ratio range is: manganese sulfate: manganese sulfate: zinc sulfate = 90:41-55:7-17; preferably, manganese sulfate: manganese sulfate: zinc sulfate = 90:41-43:7-9.

9. A mancozeb nanosuspension, characterized in that: The mancozeb nano suspension is a mancozeb nano suspension with a size of less than 100 nanometers. The mancozeb nano suspension with a size of less than 100 nanometers is formed by diluting and mixing three components with water: Component A: consisting of solid maneb and / or maneb and / or maneb, or a solid aqueous solution of maneb and / or maneb and / or maneb; Component B: composed of a mixture of manganese salt and zinc salt in a certain proportion or their aqueous solution; Component C: consists of at least one water-soluble surfactant, or its aqueous solution.

10. The mancozeb nanosuspension according to claim 9, wherein The ratio of the amount of the water-soluble surfactant to the amount of dilution water is not greater than 1:1200.

11. The mancozeb nanosuspension according to claim 9, wherein The mancozeb nano-suspension with a size of less than 100 nanometers has a stable period of hours.

12. The mancozeb nanosuspension according to claim 9, wherein The component B is a mixture of inorganic manganese salt and zinc salt in a certain proportion.

13. The mancozeb nanosuspension according to claim 12, characterized in that The manganese salt is selected from at least one of manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate; the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, and zinc nitrate.

14. The mancozeb nanosuspension according to claim 9, wherein The water-soluble surfactant is a high-molecular surfactant and / or a small-molecular surfactant.

15. The mancozeb nanosuspension according to claim 14, wherein The polymer surfactant is selected from nonionic surfactants.

16. The mancozeb nanosuspension according to claim 15, wherein The nonionic surfactant is at least one of the following options: Water-soluble starch and its derivatives, water-soluble guar gum and its derivatives, polyoxypropylene-polyoxyethylene block copolymers, alkylaryl polyoxypropylene polyoxyethylene ether, fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ether, fatty amine polyoxyethylene ether, castor oil polyoxyethylene ether, Tween, alkyl polysaccharide, polyvinyl alcohol, polyvinyl pyrrolidone.

17. A method for preparing the mancozeb nanosuspension according to claims 1 to 8; adding the diluted component A to the diluted component B under the condition that the stirring speed is not less than the effective stirring speed; Alternatively, the component B dilution is added to the component A dilution to form a mancozeb nanosuspension; The component A dilution solution and the component B dilution solution are aqueous solutions formed by diluting the following components A and B with water.

18. The preparation method according to claim 17, wherein The method of adding one component to another component is one of the following four methods: continuous addition, intermittent addition, dropwise addition, and spray addition.

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