Thiodicarb aqueous suspension concentrate and preparation method thereof

Abstract

The present invention discloses a thiodicarb aqueous suspension concentrate and a preparation method thereof. The components of the suspension concentrate include 28.5-31.5% thiodicarb, 12.1-14.6% auxiliary agents, and the rest is water, in terms of weight percentage. The auxiliary agents include dispersants, thickeners, antifreeze agents, suspension stabilizers, rot and mildew inhibitors, defoamers, and pH regulators. The dispersant is a composite mixture of four surfactants: sodium lauryl sulfate, nonionic cosmetic copolymer, EO-PO block polyether, and maleic acid-acrylic acid copolymer sodium salt. The preparation using the components provided by the present invention has the advantages of high active ingredient content, good dispersibility, and good dispersion stability of the system; the preparation process provided by the present invention has strong production continuity, can quickly disperse and dissolve materials, has good dispersion effect, and has high production efficiency; various materials are mixed more evenly, the product has strong uniformity, and the quality indicators are more stable.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticide preparation, in particular to a thiodicarb aqueous suspension concentrate and a preparation method thereof. Background Art

[0002] Thiodicarb is a highly effective, broad-spectrum, low-toxic, fast-acting, systemic carbamate insecticide. It is a low-toxic derivative of methomyl, with insecticidal activity similar to that of methomyl but lower toxicity. The active ingredient in the solution contacts and penetrates the insect's acetylcholine receptors, inhibiting esterase activity and hindering the reactivation of transducers within the insect's nerve fibers, ultimately leading to poisoning and death. If the insect's egg masses come into contact with the agent, energy metabolism is blocked, preventing the eggs from developing and hatching into larvae. Therefore, thiodicarb has a strong stomach toxicity and a limited contact effect on insect larvae and eggs. It is widely used in crops such as cotton, soybeans, corn, wheat, vegetables, fruit trees, tea, tobacco, and forestry. It is effective against Lepidoptera, Coleoptera, and Diptera pests, and is also highly active against Lepidoptera eggs. A uniform spray application of the agent diluted with water is effective against a variety of pests, including aphids and cotton bollworms, with significant insecticidal efficacy. According to statistics from the China Pesticide Industry Association, there are currently four registered thiodicarb formulations in my country: wettable powders (WPs), which account for 46.8% of all formulations; suspension concentrates (SCs), which account for 25%; water-dispersible granules (WDGs), which account for 18.8%; and suspension seed coatings (SDGs), which account for 9.4%. This suggests that traditional WPs still dominate the currently registered thiodicarb formulations, including two low-content formulations accounting for 25%. Newer, environmentally friendly formulations such as SCs and WDGs still account for a relatively small proportion.

[0003] Pesticide suspension concentrates (SCs) are one of the four environmentally friendly formulations recommended by the Food and Agriculture Organization (FAO). In recent years, due to environmental and food safety requirements, traditional formulations such as emulsifiable concentrates (ECs) and powders have been phased out. Environmentally friendly formulations, represented by SCs and water-dispersible granules (WDGs), have become a key focus of industry research and development, and are currently the fastest-growing in China. SCs are the third-largest pesticide formulation type registered in China (ECs are first, wettable powders are second). SCs use water as the dispersion medium. They grind insoluble or slightly soluble solid technical pesticides through sand milling and then, through the addition of surfactants and other additives, achieve a uniform dispersion. This creates a highly suspendable, flowable, and relatively stable liquid-solid system with fine particles (typically an average particle size of <5μm). High-quality SCs typically have a fine particle size of 1-3μm, with an average 90% particle size <5μm, and a high suspension efficiency (typically >90%, preferably >95%). They do not use any organic solvents, generate no dust, and are characterized by low toxicity and irritation to humans and animals. This formulation poses no flammability, explosion, or dust risks during packaging, storage, and transportation. Suspension concentrates offer several advantages over wettable powders, including dust-free, easy mixing, improved suspension efficiency during dilution, improved wetting, and a lower packaging volume. They are safer for operators, users, and the environment, with relatively low costs and high bioavailability. Due to their excellent dispersibility and spreadability, high suspension efficiency, strong adhesion to plant surfaces, and resistance to rain erosion, aqueous suspension concentrates offer significantly greater and longer-lasting efficacy than wettable powders. Compared to emulsifiable concentrates, they avoid the use of large amounts of organic solvents. Thiodicarb aqueous suspension concentrates offer high suspension efficiency, small particle size, high efficacy, a large active surface area, strong penetration, no dust during dispensing, and low cost. Furthermore, they exhibit excellent dispersibility and spreadability, strong spreading and adhesion to plant surfaces, resistance to rain erosion, and significant and long-lasting efficacy. Therefore, they are an environmentally friendly formulation with excellent safety, comprehensive performance, and promising application prospects.Domestically, theoretical research on pesticide suspension formulations including thiodicarb suspension concentrates has also been conducted, but the formulation of thiodicarb suspension concentrates is of only theoretical reference value. A Chinese patent (publication number CN103039471B) provides an insecticide composition containing thiodicarb and chlorfenapyr, a Chinese patent (publication number CN103004821A) provides an insecticide composition containing thiodicarb and spinosad, and a Chinese patent (publication number CN101213970A) provides an insecticide composition containing thiodicarb as an active ingredient and its application. These patents all mention the formulation and operation method of preparing thiodicarb suspension concentrates using thiodicarb in combination with other pesticides, but most of the adjuvants for different purposes are single formulations and remain at the experimental stage. In addition, there is a lack of product analysis indicators and test results, and it is impossible to judge the suitability of the process and formulation. Rational, it can only be used as a simple reference for the formula; Wang Li et al. published a paper entitled "Zeta Potential Method for Selecting Wetting and Dispersing Agents Required for Pesticide Suspensions" in the 6th issue of "Applied Chemistry" in 2010, proposing that the use of Zeta potential can be used as an indicator to characterize the dispersing performance of wetting and dispersing agents, and that the average particle size after using the compound wetting and dispersing agent is the smallest, and the change before and after heat storage is very small, and the system achieves the best dispersion effect, which has certain guiding significance for the formulation of thiodicarb suspension concentrate; Liao Kechao et al. published a paper entitled "Common Problems in Pesticide Suspensions and Their Prevention Strategies" in the 6th issue of "Chinese Pesticides", which proposed preventive measures for the common problems of pesticide suspensions, and has a certain inspiring effect on the preparation of the formula of thiodicarb suspension concentrate; but taking all factors into consideration, there is no public literature in China to date that provides a preparation process for thiodicarb suspension concentrate with excellent quality indicators such as physical stability and chemical stability.

[0004] The main problems in the preparation of thiodicarb aqueous suspension are:

[0005] 1. The product has poor physical stability and is prone to water separation, stratification, thickening, sedimentation, and agglomeration during storage. The active ingredients of the pesticide are difficult to disperse evenly, and the agglomerates may even prevent them from being poured out of the packaging. This seriously affects the promotion and use of the suspension concentrate dosage form in agricultural production.

[0006] 2. The particle size of the suspension concentrate increases significantly during storage, and the quality deteriorates rapidly;

[0007] 3. Difficult to sand grind, difficult to prepare uniform slurry during production, easy to flocculate and agglomerate;

[0008] 4. Severe foaming, lots of foam, and difficult to defoam;

[0009] 5. Poor thermal storage stability. During thermal storage, the suspension is prone to Ostwald ripening, resulting in rapid particle size growth, which can cause the suspension to become severely paste-like and solidify. Sometimes, after thermal storage, the suspension is easily agglomerated and solidified when left at room temperature, making it unable to adapt to the external environment. These problems are particularly prone to occur when the external temperature fluctuates greatly or frequently.

[0010] The existence of the above-mentioned problems has seriously restricted the quality, sales, and effectiveness of domestically produced thiodicarb aqueous suspension concentrates. With the increasing prominence of pesticide pollution and public concern for the living environment, this has become a hot topic in the formulation field. Therefore, it is necessary to thoroughly study the physicochemical properties of the technical drug thiodicarb and explore the impact of the matching of adjuvants (dispersants, thickeners, antifreeze agents, defoamers, etc.) with different structures, molecular weights, and physical and chemical properties on the quality indicators of thiodicarb aqueous suspension concentrates. The goal is to produce thiodicarb aqueous suspension concentrates with excellent suspension properties and thermal storage stability. This innovation in formulation technology aims to reduce the risks associated with pesticides and their use, which is of great significance for promoting the healthy development of the industry and achieving a win-win situation in terms of economic and social benefits. Summary of the Invention

[0011] To address the above-mentioned deficiencies in the prior art, the present invention has studied and explored the stability of suspension concentrates, selected appropriate adjuvants and their proportions, and through extensive experiments, selected and optimized the types and dosages of various adjuvants. This has resulted in a formulation for an aqueous suspension concentrate with improved dispersibility, suspension stability, and thermal storage stability, thereby forming a new production process. The effects of the present invention are achieved through the following technical solutions:

[0012] As a first aspect of the present invention, a thiodicarb aqueous suspension concentrate is provided. The components of the suspension concentrate, calculated by weight percentage, include 28.5-31.5% thiodicarb, 12.1-14.6% auxiliary agent, and the remainder is water.

[0013] The auxiliary agents include dispersants, thickeners, antifreeze agents, suspension stabilizers, antiseptics and mildew preventers, defoaming agents and pH regulators.

[0014] As a preferred solution, the dispersant is a composite mixture of four surfactants: sodium lauryl sulfate, nonionic comb copolymer, EO-PO block polyether, and maleic acid-acrylic acid copolymer sodium salt (polycarboxylic acid sodium salt).

[0015] The nonionic comb copolymer is a polymer prepared by polycondensation reaction using alkylphenol, formaldehyde and ethylene oxide as raw materials. The specific component used in the present invention is polynonylphenol polyoxyethylene ether, which is selected from liquid polynonylphenol polyoxyethylene ether NP-4, polynonylphenol polyoxyethylene ether NP-7, polynonylphenol polyoxyethylene ether NP-9 or polynonylphenol polyoxyethylene ether NP-10, and more preferably polynonylphenol polyoxyethylene ether NP-10.

[0016] As a preferred solution, the thickener is selected from a mixture of xanthan gum, magnesium aluminum silicate and carboxymethyl cellulose.

[0017] As a preferred solution, the antifreeze agent is selected from a mixture of ethylene glycol and urea.

[0018] As a preferred solution, the suspension stabilizer is selected from a mixture of polyamide preparation and EDTA.

[0019] As a preferred solution, the antiseptic and mildew preventer is selected from a mixture of sodium benzoate and 1,2-benzisothiazolin-3-one (BIT).

[0020] As a preferred solution, the defoaming agent is selected from silicone additives, C8-C 10 A mixture of fatty alcohol compounds.

[0021] As a preferred solution, the pH adjuster is tartaric acid.

[0022] Preferably, in the dispersant, the amount of sodium lauryl sulfate is 1.3-2.0%, the amount of nonionic comb copolymer is 0.9-1.5%, the amount of EO-PO block polyether is 0.9-2.3%, the amount of maleic acid-acrylic acid copolymer sodium salt is 0.8-1.6%, and the total amount of the four dispersant materials is 4.8-6.9%.

[0023] Preferably, the amount of xanthan gum is 0.01-1.0%, the amount of magnesium aluminum silicate is 0.2-1.2%, the amount of carboxymethyl cellulose is 0.01-1.0%, and the total amount of the three materials is 0.2-3%.

[0024] Preferably, in the antifreeze, the amount of ethylene glycol is 3-5%, the amount of urea is 0.1-1.5%, and the total amount of the two materials is 3.5-5.5%;

[0025] In the suspension stabilizer, the amount of polyamide preparation is 0.05-0.3%, the amount of EDTA is 0.05-0.5%, and the total amount of the two materials is 0.1-0.5%;

[0026] In the antiseptic and mildew preventer, the amount of sodium benzoate is 0.02-0.1%, the amount of 1,2-benzisothiazolin-3-one is 0.08-0.15%, and the total amount of the two materials is 0.08-0.2%;

[0027] In the defoamer, the amount of the organosilicon additive is 0.2-0.8%, the amount of the C8-C10 fatty alcohol compound is 0.1-0.6%, and the total amount of the two materials is 0.3-0.9%;

[0028] The dosage of tartaric acid as a pH adjuster is 0.05-0.1%; finally, water is added to make up to 100%.

[0029] As a second aspect of the present invention, there is provided a method for preparing a thiodicarb suspension concentrate, comprising the following steps:

[0030] Step 1, ingredients: according to the material ratio, accurately measure the various material ingredients;

[0031] Step 2, primary water dissolution: first add 60% of the total amount of water into the dissolution kettle, and add one or two components of the suspension stabilizer, thickener, preservative and mildew inhibitor, pH adjuster, defoamer and antifreeze at a time under stirring. Observe the dissolution of the material through the dissolution kettle sight glass. After the material is completely dissolved, it is ready for use to form the primary mixed material;

[0032] Step 3, secondary water dissolution: add the measured original drug thiodicarb, secondary water (the remaining 40% of the total water), and other additives into the mixing kettle and stir and mix. After fully mixing for 15-30 minutes, add the primary mixture in the dissolving kettle in step 2 into the dissolving kettle and continue stirring and mixing for 10-15 minutes to obtain the secondary mixture.

[0033] Step 4, shearing: the secondary mixture obtained in step 3 is transferred to a high shear emulsifier and sheared and crushed into μm-level particles;

[0034] Step 5, sanding process;

[0035] Step 6: Let it stand and take samples for analysis and inspection;

[0036] Step 7: Packaging.

[0037] Preferably, the suspension stabilizer, thickener, preservative and mildew preventer, pH adjuster, defoamer and antifreeze added in step 2 are EDTA, xanthan gum, carboxymethyl cellulose, sodium benzoate, tartaric acid, organosilicon additive and urea respectively.

[0038] Preferably, in step 5, the first sand grinding process is: the particles obtained in step 4 are sand ground for 30-80 minutes using a horizontal sand mill, the speed of the horizontal sand mill is 1100 rpm, and the particle size of the sample analyzed after sand grinding is not greater than 5 μm; and then the second sand grinding process is performed: the particles are sand ground for 20-60 minutes using a horizontal sand mill, the speed of the horizontal sand mill is 1440 rpm, and the particle size of the sample analyzed after sand grinding is not greater than 3 μm.

[0039] The technical solution of the present invention is based on the physicochemical properties of thiodicarb and research experience of similar products, fully considering the important role of dispersants in the preparation process and use, and combining the requirements of the solid dispersion degree and suspension stability of the suspension system. Four surfactants, including sodium lauryl sulfate, nonionic comb-shaped copolymer, EO-PO block polyether, and maleic acid-acrylic acid copolymer sodium salt (polycarboxylic acid sodium salt), are selected and determined to be compounded. Low-molecular-weight sodium lauryl sulfate mainly acts as a wetting agent. As a macromolecular block copolymer, EO-PO block polyether not only plays a role in blocking dispersion, but also has good emulsifying properties, can effectively reduce the interfacial energy of the dispersed phase, improve the emulsification of the original drug particles, and greatly improve the stability of the suspension system. The combination of polycarboxylic acids and block polyethers can effectively prevent creaming and prevent the particle size growth caused by Ostwald ripening. The specific molecular structure of the nonionic comb-shaped copolymer helps to ensure the good dispersion stability of the thiodicarb aqueous suspension.

[0040] The technical solution provided by the present invention selects three components, xanthan gum, magnesium aluminum silicate and carboxymethyl cellulose, as thickeners to adjust the viscosity of the system. Compared with monomer thickeners, the composite thickener has obvious advantages. After the multiple thickeners are combined, they can play a complementary role, expand the scope of application and improve the use function. While thickening the pesticide suspension concentrate, it also gives it excellent mechanical properties and storage stability.

[0041] The technical solution provided by the present invention fully considers the physicochemical properties and applications of thiodicarb, and reasonably matches the selected and used auxiliary agents (including dispersants, wetting agents, binders, and disintegrants), thereby avoiding the shortcomings of a single type of auxiliary agent. The auxiliary agents used are carefully selected and matched, with reasonable proportions, stable chemical properties, and do not react with each other. When combined with the thiodicarb original drug, the chemical components thereof will not be destroyed or chemical reactions will occur, thereby improving the chemical stability and physical stability of the preparation.

[0042] The technical solution provided by the present invention selects a suitable defoaming agent, and the prepared preparation has low surface tension after spraying, good wettability on the target surface, strong spreading and penetration ability, and is distributed on the target surface in the form of fine particles, which is conducive to improving the efficacy.

[0043] The preparations produced using this technical solution have advantages such as high active ingredient content, excellent dispersibility, and good dispersion stability. The process designed in this solution offers strong production continuity, rapid dispersion and dissolution of materials, excellent dispersion effects, and high production efficiency. The production equipment is safe and reliable, simple to operate and maintain, operates smoothly, and is easy to install. Within a high-speed shear emulsifier, materials are micronized, emulsified, mixed, blended, and dispersed in a short period of time. Water is added to the high-speed shear emulsifier twice: the first time with water, and the second time with water to dissolve the additive. This ensures more even mixing of the various materials, a more uniform product, and more stable quality indicators.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The preparation using the components provided by the present invention has the advantages of high active ingredient content, good dispersibility, and good dispersion stability of the system;

[0046] (2) The preparation process provided by the present invention has strong production continuity, can quickly disperse and dissolve materials, has good dispersion effect, and high production efficiency; the production equipment is safe and reliable, simple to operate and maintain, runs smoothly, and is easy to install; the material is micronized, emulsified, mixed, blended, and dispersed in a high-speed shear emulsifier in a short time, which greatly reduces the preparation efficiency;

[0047] (3) Water is added to the high-speed shear emulsifier twice, the first time water is added, and the second time water is added to dissolve the additive. This way, the various materials are mixed more evenly, the product is more uniform, and the quality indicators are more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0049] Figure 1 The present invention provides a flow chart of the preparation method of the thiodicarb aqueous suspension concentrate. DETAILED DESCRIPTION

[0050] For the preparation of pesticide suspension concentrates, the goal is to improve the suspension rate and suspension stability of the preparation and to improve the thermal storage stability of the preparation.

[0051] On the one hand, pesticide suspension concentrates are highly dispersed, multi-phase, and complex systems, and their stability is affected by a variety of factors. In addition to the physical and chemical properties of the pesticide active ingredient itself (such as physical form, melting point, solubility in water, volatility, hydrolytic stability, chemical stability, photostability, and thermal stability), the added surfactants (wetting agents, dispersants) and various additives (such as antifreeze agents, thickeners, preservatives, defoamers, and other additives) also need to be considered. The interactions between these factors will affect the stability of the suspension concentrate.

[0052] On the other hand, the storage stability of suspension concentrates has always been a major obstacle to their development and production. Pesticide suspension concentrates are inherently unstable because they are a highly dispersed, multiphase, complex system composed not only of the active ingredient and dispersion medium, but also of a large number of adjuvant ingredients. They always exist as a highly concentrated suspension, which can lead to chemical instability during long-term storage. More commonly, however, they present physical stability issues. The poor physical stability of suspension concentrates is often due to the flocculation, coagulation, and even aggregation of particles in the dispersed phase caused by collisions during Brownian motion, as well as irreversible coagulation and aggregation caused by interparticle van der Waals forces. To improve this situation, particles can be given an adequate protective layer to prevent interparticle attraction and aggregation. This can be achieved by using ionic dispersants that provide electrostatic repulsion, non-ionic dispersants that provide steric hindrance, or higher-performing polymeric surfactant dispersants.

[0053] In view of the problems of poor suspension stability, poor heat storage stability, easy generation of bubbles and difficulty in eliminating bubbles during the preparation process, water precipitation, thickening, precipitation and other poor physical stability of the existing thiodicarb aqueous suspension in China, according to (1) Stokes Law (1845), the physical stability of the suspension is related to factors such as the viscosity and density difference of the preparation and the particle size of the suspended particles; (2) basic organic chemical structure theory, the structure of the compound determines the properties, and the unique amphiphilic molecular structure of the surfactant determines their basic properties, mainly including wetting, penetration, dispersion, emulsification, solubilization and other functions. Among them, adding a surfactant with dispersing effect to the system can form a uniform and stable suspension. In the suspension system, collisions between particles are inevitable. The charge of the particles themselves and the adsorption layer formed by the surfactant on the particle surface prevent the irreversible flocculation between the suspended particles. This is the dispersing principle of the surfactant. Ionic surfactants work due to the repulsive force generated by the double electrical layer formed at the particle / solution interface; non-ionic surfactants and macromolecular dispersants adsorb on the surface of the original drug particles and form "steric hindrance", which causes the particles to repel each other and prevent aggregation. Selecting an adjuvant that reasonably matches the original drug is the key to ensuring the physical stability of the suspension during storage.

[0054] The present invention provides a preparation of a thiodicarb suspension concentrate, wherein a dispersant, a thickener, an antifreeze agent, a suspension stabilizer, a preservative and mildew preventer, a defoaming agent and a pH regulator are selected and formulated.

[0055] 1. Selection of dispersant

[0056] Dispersants are surfactants that help particles split and disperse, prevent flocculation, and stabilize particles. They are added to suspensions to help disperse and suspend particles during production, ensuring that the formulation product can be redispersed into a suitable suspension for spraying when diluted in water. Dispersants have the ability to strongly adsorb on the surface of particles and provide electrical repulsion and steric barriers to prevent particle reaggregation and sedimentation. Factors to consider when selecting dispersants include: (1) they do not decompose the original drug or promote its decomposition in the presence of large amounts of water; (2) they are not prone to decomposition under acidic or alkaline conditions and in water; (3) they are conducive to reducing particle size and maintaining low viscosity between particles during sand milling of pesticide active ingredient slurry, facilitating dispersion and processing; (4) they have good wetting effects on the outer surface and porous surface of the dispersed pesticide active ingredient particles; and (5) they can form a stable suspension dispersion. If the selected dispersant is not suitable for the physical and chemical properties of thiodicarb, the stability of the suspension prepared will be very poor, and coagulation and bottoming will usually occur during storage, thus affecting product quality and efficacy. The wetting and dispersing agents of pesticide suspension concentrates are mainly anionic and nonionic surfactant monomers or a combination of anionic and nonionic surfactants. The mixture of the two can change the thickness of the cross-adsorption layer, thereby improving the physical stability of the suspension concentrate.

[0057] After repeated experiments and comparisons, a four-surfactant combination was determined: sodium lauryl sulfate, a nonionic comb copolymer, an EO-PO block polyether, and sodium salt of a maleic acid-acrylic acid copolymer (sodium salt of a polycarboxylic acid). The dispersing ability of a surfactant depends on its molecular weight and the characteristics of its hydrophobic group. Generally speaking, hydrophobic surfactants with large molecular weights diffuse more slowly to the particle surface, but have strong adsorption capacity and are less susceptible to surface transfer, thus providing long-term stability for the pesticide formulation. Maleic acid-acrylic acid copolymer sodium salt, due to its high molecular weight, is less sensitive to ions, pH, and temperature in the suspension system. It offers high dispersion stability, is less susceptible to sedimentation and flocculation, significantly reduces dispersion viscosity, and exhibits good fluidity at high solids contents. The EO-PO block polyether is a nonionic surfactant and a macromolecular block copolymer, which exhibits excellent "steric hindrance" effects. The mechanism of its stability is generally believed to be that the block dispersant adsorbs at the interface of the dispersed phase particles, forming a dense adsorption layer. This dense adsorption layer between the dispersed phase particles creates a steric hindrance that prevents further contact between the particles, thereby maintaining the dispersion stability of the aqueous suspension. Structurally, the macromolecular chain possesses two types of groups: an "oil-like" group that strongly adsorbs to dispersed pesticide particles, and a "hydrophilic" group that effectively hydrates them. These groups are also flexible and repel each other, ensuring excellent dispersion stability in the pesticide suspension concentrate. The macromolecular block copolymer not only acts as a barrier to dispersion but also possesses excellent emulsifying properties, effectively reducing the interfacial energy of the dispersed phase, enhancing the emulsification of the original pesticide particles, and significantly improving the stability of the suspension system. The combination of polycarboxylic acids and block polyethers effectively prevents creaming and particle size growth caused by Ostwald ripening. Sodium lauryl sulfate primarily acts as a wetting agent. The nonionic comb-type dispersant, through its anchoring groups, adsorbs onto the surface of thiodicarb particles, imparting a charge to the particles and creating a double layer around them, increasing electrostatic repulsion. The hydrophilic, solvated branches extend into the water, creating steric hindrance that separates the particles and enhances their stability. To date, no nonionic comb-type copolymers with this structure have been used in the production of pesticide suspension concentrates in China.

[0058] 2. Selection of thickener

[0059] Thickeners, also known as gelling agents, increase the viscosity or consistency of formulated products, maintaining a uniform, stable suspension or emulsion, or forming a gel. Pesticide suspension concentrates (SCs) are coarsely dispersed systems, and the technical particles tend to settle under gravity, making them unstable suspension systems and subject to suspension stability issues. According to the classic Stokes sedimentation equation, thickeners are necessary to achieve an appropriate viscosity (250-1000 cp) in SCs to reduce particle settling. Thickeners are rheological modifiers with specific rheological properties. They are a type of additive that improves the physical characteristics and viscosity of SCs. During SC preparation, they increase and adjust the viscosity of materials, facilitating the dispersion of pesticide particles and other materials. During storage, they prevent sedimentation and agglomeration in various media. Thickeners not only thicken SCs but also impart excellent mechanical properties and storage stability. Even with a small addition, they can significantly increase the viscosity or consistency of the product, making them an indispensable component of SCs. Correct selection and use of thickeners are very important for solving various rheological problems that arise during the production, storage and use of pesticide suspension concentrates. The main requirements for pesticide suspension thickeners are: (1) good compatibility with the stock solution, without affecting the appearance, color and function of the product; (2) increasing the viscosity of the suspension, avoiding the sedimentation of the raw materials during storage, and not easy to stratify and flocculate. Maintaining the consistency of the product before and after production; (3) strong thickening function, adding a small amount, and increasing the thickening amount to improve the rheological properties; (4) good water resistance, alkali resistance, good suspension, uniform mixing performance, good thickening, low cost; (5) good solubility and viscosity characteristics, non-thermal gelation, and high shear viscosity. Thickeners are also called food glues or dextrins. The thickener molecular structure has many hydrophilic groups such as hydroxyl, carboxyl, amino and carboxylate groups. After these groups undergo hydration with water molecules, they are highly dispersed in water in a molecular state, forming a single-phase uniform dispersion system with high viscosity. It is precisely because of the special molecular structure of the thickener that it plays the role of thickening, stabilizing, suspending, improving gel texture and structure under different combination conditions. In research, it was found that using a single thickener often leads to obvious defects. Compared with monomeric thickeners, composite thickeners have obvious advantages. After multiple thickeners are combined, they can play a complementary role, expand the scope of application, and improve the use function. The present invention selects three components, xanthan gum, magnesium aluminum silicate, and carboxymethyl cellulose, as thickeners to adjust the viscosity of the system, thereby reducing the sedimentation of thiodicarb original drug particles during storage and improving the suspension stability of thiodicarb aqueous suspension concentrate.

[0060] 3. Selection of antifreeze

[0061] Because SCs contain a considerable amount of water, antifreeze is added to prevent freezing during storage and transportation due to weather conditions, which could compromise the SC's performance. This increases the SC's freeze-thaw resistance and improves its low-temperature stability. Ethylene glycol and propylene glycol are generally suitable antifreeze agents. Through multiple experiments, we determined that ethylene glycol and urea are the preferred antifreeze agents.

[0062] 4. Suspension stabilizer

[0063] Suspension stabilizers are commonly used in suspensions to keep fine particles in suspension. They have high dispersion, a large surface area, and strong adsorption capacity. They can affect the surrounding water and other particles, preventing them from sinking quickly. This thickens the suspension and acts as an additive to prevent precipitation of components. Traditional suspending agents, primarily chlorides such as sodium chloride (NaCl) and ammonium chloride (NH4Cl), have been used. Experimentation has led to the use of polyamide preparations and EDTA as suspension stabilizers.

[0064] 5. Anticorrosion and antifungal agents

[0065] Pesticide suspension concentrates are typically supplemented with preservatives and mildew inhibitors (also known as pesticide formulation protectants). Aqueous acetaldehyde solutions are commonly used, but polyoxymethylene, sodium citrate, sodium salicylate, and sorbitol can also be used. Because thiodicarb is stable between pH 3 and 6 and does not decompose, sodium benzoate, an acidic preservative, offers excellent preservative effects under acidic conditions. It also effectively prevents thiodicarb's decomposition and maintains its stability. 1,2-Benzisothiazolin-3-one (BIT) exhibits excellent stability under acidic conditions, effectively preventing thiodicarb's decomposition and providing industrial sterilization and preservative properties. Based on the physical and chemical properties of thiodicarb, a dual-component combination of sodium benzoate and 1,2-Benzisothiazolin-3-one (BIT) is used as a preservative and mildew inhibitor.

[0066] 6. Selection of defoaming agent

[0067] Since the suspending agent contains surfactants, the high-speed rotating dispersing disk during the production process easily brings ambient air into the dispersion system to form extremely small bubbles; foam will inevitably be generated when the product is diluted. Foam will bring many inconveniences to the processing, not only affecting viscosity, metering and product packaging, but also reducing production efficiency and affecting user use and drug efficacy. Therefore, the addition of a defoamer is necessary. Based on experience and the physical and chemical properties of thiodicarb, silicone additives, C8-C 10The fatty alcohol compound also acts as a defoamer. The organosilicon additive in the formulation has stronger surface activity than common nonionic surfactants, effectively reducing the surface tension of the solution. The critical surface tension of a plant is a crucial parameter for pesticide application. When the surface tension of the spray solution is lower than that of a particular plant, the pesticide can wet and spread on that plant surface. This organosilicon reduces the contact angle between the spray solution and the foliage, thereby increasing spray coverage. It also improves the adhesion of pesticide droplets to plant leaves, potentially reducing spray volumes. Furthermore, since more of the spray solution adheres to the target, the amount of water required to cover a specific foliage surface is reduced.

[0068] 7. pH adjuster selection

[0069] This is a crucial means of ensuring the chemical stability of the active ingredient in the formulation. Thiodicarb is stable in neutral and slightly acidic media, but slowly decomposes when the pH exceeds 9. Therefore, the addition of a pH-adjusting agent is necessary to tailor the pH to the technical product's needs. This prevents decomposition or other chemical reactions that could affect the active ingredient content and storage stability. Experimentation has determined the use of tartaric acid as a pH adjuster.

[0070] The present invention will be described in detail below with reference to specific examples. It should be noted that the following examples are intended only to further illustrate the present invention and are not to be construed as limiting the scope of the present invention. Non-essential improvements and adjustments made by professionals in this field based on the above-described disclosure of the present invention remain within the scope of the present invention. Furthermore, unless otherwise noted, all raw materials and equipment used are commercially available and commonly used in the art. Unless otherwise specified, all measurement parameters refer to mass or weight content.

[0071] Example 1

[0072] Step 1: Ingredients: Accurately measure the raw materials according to the following weight ratio.

[0073] Main ingredient: Thiodicarb technical (100%) 30%;

[0074] Dispersant: sodium lauryl sulfate 1.3%, nonionic comb copolymer using polynonylphenol polyoxyethylene ether (NP-10) 1.5%, EO-PO block polyether 0.9%, maleic acid-acrylic acid copolymer sodium salt 1.6%;

[0075] Thickener: xanthan gum 0.06%, magnesium aluminum silicate 0.8%, carboxymethyl cellulose 0.5%;

[0076] Antifreeze: ethylene glycol 3.2%, urea 2.1%;

[0077] Suspension stabilizer: polyamide preparation 0.1%, EDTA 0.1%;

[0078] Preservatives and mildew inhibitors: sodium benzoate 0.02%, BIT 0.06%;

[0079] Defoaming agent: 0.5% silicone additive, C8-C 10 Fatty alcohol compounds 0.4%;

[0080] pH adjuster: tartaric acid 0.08%.

[0081] Step 2, primary water dissolution: first add 60% of the total amount of water into the dissolution kettle, and add the measured EDTA, xanthan gum, sodium benzoate, tartaric acid, carboxymethyl cellulose, silicone additive, and urea in sequence under stirring. Observe the dissolution of the materials through the dissolution kettle sight glass. After the materials are dissolved, they are ready for use to obtain a primary mixture.

[0082] Step 3, Secondary Water Dissolution: Add the measured original drug, secondary water (the remaining 40% of the total water), and other additives not dissolved in the water to the mixing kettle and mix thoroughly. The materials are continuously rotated and stirred in the mixing kettle by a special stirring device inside the kettle to continuously create new interfaces, shear, compress, and fold the materials, and stir and mix them. Mix for 15 minutes.

[0083] Step 4: Add the dissolved material from step 2 from the dissolving kettle to the mixing kettle to obtain a primary mixture, and continue mixing for 15 minutes.

[0084] Step 5: After the mixture is mixed once, the material is added to the high shear emulsifier by gravity and the suction of the high shear emulsifier. The strong shearing, dispersion, impact, turbulence and other processes generated between the high-speed rotating rotor and stator make the material be cut in the shear gap and quickly broken into μm-level particles.

[0085] Step 6: The particles obtained in step 5 are sand-milled in a horizontal sand mill for 40 minutes at a speed of 1100 rpm. After sand-milling, samples are taken for analysis and the particle size is no greater than 5 μm. A second sand-milling step is then performed: sand-milling in a horizontal sand mill for 50 minutes at a speed of 1440 rpm. After sand-milling, samples are taken for analysis and the particle size is no greater than 3 μm. The particles are then placed in a standing tank, sampled and analyzed for all indicators, and packaged.

[0086] The test results of the prepared products are shown in Table 1.

[0087] Table 1 Test results of the prepared thiodicarb aqueous suspension

[0088]

[0089]

[0090] Thiodicarb decomposition rate = (analysis result of the preparation - analysis result after hot storage) ÷ analysis result of the preparation × 100%.

[0091] The suspension rate is determined according to GB / T 14825-2006.

[0092] Low temperature stability is tested according to the low temperature stability test method of pesticides GB / T19137-2003; this national standard stipulates that the suspension rate and wet sieve test indicators tested under the specified test conditions still meet this standard and are qualified.

[0093] The hot storage stability is tested according to 2.3 of GB / T19136-2003. The test results show that after hot storage, the relative decomposition rate of thiodicarb is ≤5.0%, the relative decomposition rate of methomyl is ≤0.25%, the suspension rate is ≥90.0%, and the pH value, pourability and wet sieve test all meet the standard requirements, indicating that the hot storage stability is qualified.

[0094] Combined with the results of hot storage stability analysis, after hot storage, the relative decomposition rate of thiodicarb was 2.99% (≤5.0%), the relative decomposition rate of methomyl was 0 (≤0.25%), the suspension rate was 96.2% (≥90.0%), the pH value, pourability, and wet sieve test all met the standard requirements, so the hot storage stability was qualified.

[0095] Combined with the cold storage stability analysis results, after cold storage, all test indicators including suspension rate and wet screening test indicators are qualified, so the cold storage stability is qualified.

[0096] Example 2

[0097] 1. Measure the various raw materials according to the following material proportions.

[0098] Thiodicarb technical (discounted 100%) 30%;

[0099] Dispersant: sodium lauryl sulfate 1.3%, nonionic comb copolymer using polynonylphenol polyoxyethylene ether (NP-7) 1.5%, EO-PO block polyether 1.2%, maleic acid-acrylic acid copolymer sodium salt 0.8%;

[0100] Thickener: xanthan gum 0.08%, magnesium aluminum silicate 0.8%, carboxymethyl cellulose 0.4%;

[0101] Antifreeze: ethylene glycol 3.8%, urea 1.1%;

[0102] Suspension stabilizer: polyamide preparation 0.08%, EDTA 0.13%;

[0103] Preservatives and mildew inhibitors: sodium benzoate 0.06%, BIT 0.09%;

[0104] Defoaming agent: 0.4% silicone additive, C8-C 10 Fatty alcohol compounds 0.3%;

[0105] pH adjuster: tartaric acid 0.06%.

[0106] 2. Dissolve in water once

[0107] First, add 60% of the total amount of water to the dissolving kettle. Then, under stirring, add the measured EDTA, xanthan gum, sodium benzoate, tartaric acid, carboxymethyl cellulose, silicone additive, and urea in sequence. Observe the dissolution of the materials through the dissolving kettle sight glass. Once the materials are dissolved, set aside.

[0108] 3. Preparation

[0109] The measured amount of technical material, secondary water (the remaining 40% of the total amount), and any undissolved additives were added to a mixing kettle for thorough mixing. The materials were continuously stirred and rotated within the mixing kettle by a special agitator, creating new interfaces, shearing, compressing, and folding the materials, and stirring and mixing them. Mixing continued for 12 minutes. The primary water, which had already dissolved the materials, was then added from the dissolving kettle to the mixing kettle, and mixing continued for 20 minutes. After the primary water addition and mixing were complete, the materials were fed into the high-shear emulsifier using gravity and the suction of the high-shear emulsifier. The strong shearing, dispersion, impact, and turbulent flow generated between the high-speed rotating rotor and stator caused the materials to be cut within the shear gaps, rapidly breaking them into micron-sized particles. The materials then passed through the high-shear emulsifier's first and second sand milling stages, sand milling for 50 and 60 minutes respectively. Each sand milling stage was inspected at each stage. The materials were then placed in a holding tank, sampled, and analyzed for all indicators, and packaged. The test results for the resulting product are shown in Table 2.

[0110] Table 2 Test results of the prepared thiodicarb aqueous suspension

[0111]

[0112]

[0113] Combined with the results of hot storage stability analysis, after hot storage, the relative decomposition rate of thiodicarb was 3.58% (≤5.0%), the relative decomposition rate of methomyl was 0 (≤0.25%), the suspension rate was 96.7% (≥90.0%), the pH value, pourability, and wet sieve test all met the standard requirements, so the hot storage stability was qualified.

[0114] Combined with the cold storage stability analysis results, after cold storage, all test indicators including suspension rate and wet screening test indicators are qualified, so the cold storage stability is qualified.

[0115] Example 3

[0116] 1. Measure the various raw materials according to the following material proportions.

[0117] Thiodicarb technical (discounted 100%) 30%;

[0118] Dispersant: sodium lauryl sulfate 2%, nonionic comb copolymer using polynonylphenol polyoxyethylene ether (NP-9) 0.9%, EO-PO block polyether 1.3%, maleic acid-acrylic acid copolymer sodium salt 1.1%;

[0119] Thickener: xanthan gum 0.05%, magnesium aluminum silicate 1.2%, carboxymethyl cellulose 1.1%;

[0120] Antifreeze: ethylene glycol 4%, urea 0.5%;

[0121] Suspension stabilizer: polyamide preparation 0.12%, EDTA 0.11%;

[0122] Preservatives and mildew inhibitors: sodium benzoate 0.05%, BIT 0.08%;

[0123] Defoaming agent: 0.3% silicone additive, C8-C 10 Fatty alcohol compounds 0.1%;

[0124] pH adjuster: tartaric acid 0.07%.

[0125] 2. Dissolve in water once

[0126] First, add 60% of the total amount of water to the dissolving kettle. Then, under stirring, add the measured EDTA, xanthan gum, sodium benzoate, tartaric acid, carboxymethyl cellulose, silicone additive, and urea in sequence. Observe the dissolution of the materials through the dissolving kettle sight glass. Once the materials are dissolved, set aside.

[0127] 3. Preparation

[0128] The measured amount of technical material, secondary water (the remaining 40% of the total amount), and any undissolved additives were added to a mixing kettle for thorough mixing. The materials were continuously stirred and rotated within the mixing kettle by a special agitator, creating new interfaces, shearing, compressing, and folding the materials, and stirring and mixing them. Mixing continued for 25 minutes. The primary water, which had already dissolved the materials, was then added from the dissolving kettle to the mixing kettle, and mixing continued for 12 minutes. After the primary water addition and mixing were complete, the materials were fed into the high-shear emulsifier using gravity and the suction of the high-shear emulsifier. The strong shearing, dispersion, impact, and turbulent flow generated between the high-speed rotating rotor and stator caused the materials to be cut within the shear gaps, rapidly breaking them into micron-sized particles. The materials then passed through the high-shear emulsifier's first and second sand-grinding stages, sand-grinding for 60 and 40 minutes, respectively. Each sand-grinding stage was inspected at each stage. The materials were then placed in a holding tank, sampled, and analyzed for all indicators, and packaged. The test results for the resulting product are shown in Table 3.

[0129] Table 3 Test results of the prepared thiodicarb aqueous suspension

[0130]

[0131]

[0132] Combined with the results of hot storage stability analysis, after hot storage, the relative decomposition rate of thiodicarb was 3.05% (≤5.0%), the relative decomposition rate of methomyl was 0 (≤0.25%), the suspension rate was 96.6% (≥90.0%), the pH value, pourability, and wet sieve test all met the standard requirements, so the hot storage stability was qualified.

[0133] Combined with the cold storage stability analysis results, after cold storage, all test indicators including suspension rate and wet screening test indicators are qualified, so the cold storage stability is qualified.

[0134] Example 4

[0135] 1. Measure the various raw materials according to the following material proportions.

[0136] Thiodicarb technical (discounted 100%) 30%;

[0137] Dispersant: sodium lauryl sulfate 1.9%, nonionic comb copolymer using polynonylphenol polyoxyethylene ether (NP-4) 1.1%, EO-PO block polyether 2.3%, maleic acid-acrylic acid copolymer sodium salt 1.6%;

[0138] Thickener: xanthan gum 0.02%, magnesium aluminum silicate 1.9%, carboxymethyl cellulose 0.3%;

[0139] Antifreeze: ethylene glycol 4.1%, urea 0.2%;

[0140] Suspension stabilizer: polyamide preparation 0.06%, EDTA 0.08%;

[0141] Preservatives and mildew inhibitors: sodium benzoate 0.08%, BIT 0.1%;

[0142] Defoaming agent: 0.6% silicone additive, C8-C 10 Fatty alcohol compounds 0.2%;

[0143] pH adjuster: tartaric acid 0.06%.

[0144] 2. Dissolve in water once

[0145] First, add 60% of the total amount of water to the dissolving kettle. Then, under stirring, add the measured EDTA, xanthan gum, sodium benzoate, tartaric acid, carboxymethyl cellulose, silicone additive, and urea in sequence. Observe the dissolution of the materials through the dissolving kettle sight glass. Once the materials are dissolved, set aside.

[0146] 3. Preparation

[0147] The measured amount of technical material, secondary water (the remaining 40% of the total amount), and any undissolved additives were added to a mixing kettle for thorough mixing. The materials were continuously stirred and rotated within the mixing kettle by a special agitator, creating new interfaces, shearing, compressing, and folding the materials, and stirring and mixing them. Mixing continued for 10 minutes. The primary water, which had already dissolved the materials, was then added from the dissolving kettle to the mixing kettle, and mixing continued for 25 minutes. After the primary water addition and mixing were complete, the materials were fed into the high-shear emulsifier using gravity and the suction of the high-shear emulsifier. The strong shearing, dispersion, impact, and turbulent flow generated between the high-speed rotating rotor and stator caused the materials to be cut within the shear gaps, rapidly breaking them into micron-sized particles. The materials then passed through the high-shear emulsifier's first and second sand milling stages, sand milling for 70 and 30 minutes respectively. Each sand milling stage was inspected at each stage. The materials were then placed in a holding tank, sampled, and analyzed for all indicators, and packaged. The test results for the resulting product are shown in Table 4.

[0148] Table 4 Test results of the prepared thiodicarb aqueous suspension

[0149]

[0150] Combined with the results of hot storage stability analysis, after hot storage, the relative decomposition rate of thiodicarb was 1.94% (≤5.0%), the relative decomposition rate of methomyl was 0 (≤0.25%), the suspension rate was 95.6% (≥90.0%), the pH value, pourability, and wet sieve test all met the standard requirements, so the hot storage stability was qualified.

[0151] Combined with the cold storage stability analysis results, after cold storage, all test indicators including suspension rate and wet screening test indicators are qualified, so the cold storage stability is qualified.

[0152] Example 5

[0153] 1. Ingredients

[0154] Measure the various raw materials according to the following material ratios:

[0155] Thiodicarb technical (discounted 100%) 30%

[0156] Dispersant: sodium lauryl sulfate 1.8%, nonionic comb copolymer 1.1%, EO-PO block polyether 2.1%, maleic acid-acrylic acid copolymer sodium salt 1.5%;

[0157] Thickener: xanthan gum 0.03%, magnesium aluminum silicate 1.5%, carboxymethyl cellulose 0.5%;

[0158] Antifreeze: ethylene glycol 3.5%, urea 0.8%;

[0159] Suspension stabilizer: polyamide preparation 0.3%, EDTA 0.09%;

[0160] Preservatives and mildew inhibitors: sodium benzoate 0.08%, BIT 0.15%;

[0161] Defoaming agent: 0.3% silicone additive, C8-C 10 Fatty alcohol compounds 0.5%;

[0162] pH adjuster: tartaric acid 0.05%.

[0163] 2. Dissolve in water once

[0164] First, add 60% of the total amount of water to the dissolving kettle. Then, under stirring, add the measured EDTA, xanthan gum, sodium benzoate, tartaric acid, carboxymethyl cellulose, silicone additive, and urea in sequence. Observe the dissolution of the materials through the dissolving kettle sight glass. Once the materials are dissolved, set aside.

[0165] 3. Preparation

[0166] The measured amount of technical material, secondary water (the remaining 40% of the total amount), and any undissolved additives were added to a mixing kettle for thorough mixing. The materials were continuously stirred and rotated within the mixing kettle by a special agitator, creating new interfaces, shearing, compressing, and folding the materials, and stirring and mixing them. Mixing continued for 20 minutes. The primary water, which had already dissolved the materials, was then added from the dissolving kettle to the mixing kettle, and mixing continued for 15 minutes. After the primary water addition and mixing were complete, the materials were fed into the high-shear emulsifier using gravity and the suction of the high-shear emulsifier. The strong shearing, dispersion, impact, and turbulent flow generated between the high-speed rotating rotor and stator caused the materials to be cut within the shear gaps, rapidly breaking them into micron-sized particles. The materials then passed through the high-shear emulsifier's first and second sand milling stages, sand milling for 65 and 55 minutes respectively. Each sand milling stage was inspected at each stage. The materials were then placed in a holding tank, sampled, and analyzed for all indicators, and packaged. The test results for the resulting product are shown in Table 5.

[0167] Table 5 Test results of the prepared thiodicarb aqueous suspension

[0168]

[0169]

[0170] Combined with the results of hot storage stability analysis, after hot storage, the relative decomposition rate of thiodicarb was 2.27% (≤5.0%), the relative decomposition rate of methomyl was 0 (≤0.25%), the suspension rate was 96.1% (≥90.0%), the pH value, pourability, and wet sieve test all met the standard requirements, so the hot storage stability was qualified.

[0171] Combined with the cold storage stability analysis results, after cold storage, all test indicators including suspension rate and wet screening test indicators are qualified, so the cold storage stability is qualified.

[0172] Through the application of Examples 1-5, the products prepared using the process of the present invention are qualified in all indicators, which shows that the process technology is stable, operable and repeatable, and the technology is reasonable.

[0173] This product has obtained the Pesticide Registration Certificate (Registration No. PD20090688) issued by the Ministry of Agriculture and Rural Affairs of China, and the issuance date was October 27, 2018.

[0174] Comparative Example 1: Using the same raw materials and proportions as in Example 5, the following operations are different:

[0175] 2. Dissolve in water once

[0176] First, add 60% of the total amount of water to the dissolving kettle. Then, under stirring, add all the measured thickeners, antifreeze agents, suspension stabilizers, antiseptics, antifungal agents, defoamers, and pH adjusters in sequence. Observe the dissolution of the materials through the sight glass of the dissolving kettle. Once the materials are dissolved, set aside.

[0177] 3. Preparation

[0178] The measured original drug, secondary water (the remaining 40% of the total amount of water), and other additives not dissolved in water were added to the mixing kettle and mixed thoroughly. The remaining operations were the same as in Example 5. The test results of the prepared product are shown in Table 6.

[0179] Table 6 Test results of the prepared thiodicarb aqueous suspension

[0180]

[0181] The analysis results show that the product produced by adding the thickener, antifreeze, suspension stabilizer, preservative and mildew inhibitor, defoamer, and pH adjuster all at once failed the wet sieve test, pourability, and sustained foam volume tests, and the suspension rate was only 91.4%. This is primarily due to the fact that after all the components, including the thickener, antifreeze, suspension stabilizer, preservative and mildew inhibitor, defoamer, and pH adjuster, were dissolved in water and then sand-milled with thiodicarb technical and other additives, the different physical and chemical properties and expansion degrees after dissolving in water resulted in uneven mixing of the materials, resulting in the product failing. Therefore, it is not necessary to conduct hot and cold storage stability analyses on this product.

[0182] Comparative Example 2: The same production process as Example 5 was used, except that:

[0183] The total amount of dispersant in the material ratio remains unchanged (a total of 6.5%).

[0184] Sodium lauryl sulfate 1.8%

[0185] Maleic acid-acrylic acid copolymer sodium salt 4.7%

[0186] No nonionic comb copolymer and EO-PO block polyether dispersants are used

[0187] The operation was the same as in Example 5. The test results of the obtained product are shown in Table 7.

[0188] Table 7 Test results of the prepared thiodicarb aqueous suspension

[0189]

[0190] The above analysis results indicate that without the use of both nonionic comb copolymer and EO-PO block polyether dispersants, the suspension concentrate product failed to meet the standards in multiple indicators. The primary reason is that when using only sodium lauryl sulfate and sodium maleic acid-acrylic acid copolymer as dispersants, the strong solvation of these two active agents, especially the sodium maleic acid-acrylic acid copolymer, causes the dispersant to readily dislodge from the thiodicarb surface. Furthermore, entanglement between hydrophilic chains easily occurs, leading to flocculation and reduced dispersion effectiveness. Sodium lauryl sulfate, due to its low molecular weight and low viscosity, has a weak binding affinity with the thiodicarb surface, easily forming "bridging" aggregation, which reduces dispersion stability and results in product failure. Therefore, hot and cold storage stability analyses of the product are meaningless.

[0191] Comparative Example 3

[0192] The same production process as in Example 5 was used, except that:

[0193] The total amount of dispersant in the material ratio remains unchanged (a total of 6.5%).

[0194] Nonionic comb copolymer 3.2%

[0195] EO-PO block polyether 3.3%

[0196] No dispersants such as sodium lauryl sulfate and sodium maleic acid-acrylic acid copolymer are used

[0197] The operation process is the same as that of Example 5. The test results of the obtained product are shown in Table 8.

[0198] Table 8 Test results of the prepared thiodicarb aqueous suspension

[0199]

[0200] The above analysis results indicate that omitting the use of sodium lauryl sulfate and sodium maleic acid-acrylic acid copolymer dispersants results in multiple substandard suspension concentrates. This is primarily due to the low molecular weight of sodium lauryl sulfate acting primarily as a wetting agent, while sodium maleic acid-acrylic acid copolymer has a strong solvating effect. While using only the nonionic comb copolymer HE and EO-PO block polyether as dispersants helps prevent particle size growth due to Ostwald ripening, it also reduces the overall dispersion stability of the system, resulting in substandard product. Therefore, it is not necessary to conduct storage stability and cold storage stability analyses on this product.

[0201] Comparative Example 4 uses the same production process as Example 5, except that:

[0202] The suspension stabilizer was changed from polyamide preparation and EDTA to sodium chloride and ammonium chloride. The total amount of sodium chloride and ammonium chloride remained unchanged at 0.39%, of which sodium chloride was 0.15% and ammonium chloride was 0.24%.

[0203] Other technical materials, adjuvants and water remain unchanged.

[0204] The operation was the same as in Example 5. Due to the change in raw materials, only the suspension rate, wet sieve test, pourability, and sustained foam volume of the prepared product were tested. If any of these parameters failed, the product was deemed unqualified, and the remaining parameters were not tested. The test results of the prepared product are shown in Table 9.

[0205] Table 9 Test results of the prepared thiodicarb aqueous suspension

[0206]

[0207] The above analysis shows that using sodium chloride and ammonium chloride instead of polyamide and EDTA only resulted in passing wet sieve test and sustained foam volume, while failing suspension rate and pourability. This is because polyamide, as a high-molecular-weight polymer, can achieve significantly better suspension performance than sodium chloride and ammonium chloride alone under the same conditions.

[0208] Comparative Example 5 uses the same production process as Example 5, except that:

[0209] The dosage of the four additives, dispersant, thickener, antifreeze agent and suspension stabilizer, has been adjusted. The specific dosage is as follows: Dispersant: sodium lauryl sulfate 2.4%, nonionic cosmetic copolymer 1.9%, EO-PO block polyether 1.7%, maleic acid-acrylic acid copolymer sodium salt 1.9%; total amount 7.9%

[0210] Thickener: xanthan gum 0.95%, magnesium aluminum silicate 0.15%, carboxymethyl cellulose 1.05%; total amount 3.15%;

[0211] Antifreeze: ethylene glycol 4.9%, urea 1.3%; total amount 6.2%;

[0212] Suspension stabilizer: polyamide preparation 0.25%, EDTA 0.4%; total amount 0.65%;

[0213] The dosage of other technical materials and additives remains unchanged, and water is added to 100%.

[0214] The operation was the same as in Example 5. Due to the change in raw materials, only the suspension rate, wet sieve test, pourability, and sustained foam volume of the prepared product were tested. If any of these parameters failed, the product was deemed unqualified, and the remaining parameters were not tested. The test results of the prepared product are shown in Table 9.

[0215] Table 9 Test results of the prepared thiodicarb aqueous suspension

[0216]

[0217] The above analysis shows that increasing the dosage of the four additives—dispersant, thickener, antifreeze, and suspension stabilizer—only qualified for the wet sieving test and sustained foam volume; the suspension rate and pourability failed. This is because the increased dosage of the four additives, compared to the material ratio screened under optimal conditions, resulted in poor compatibility between the additives, a decrease in suspension rate, and material accumulation at the bottom of the experimental container, resulting in poor pourability and excessive residue after washing.

[0218] Comparative Example 6 uses the same production process as Example 5, except that:

[0219] The dosage of the four additives, dispersant, thickener, antifreeze agent and suspension stabilizer, has been adjusted. The specific dosage is as follows: Dispersant: sodium lauryl sulfate 0.9%, nonionic cosmetic copolymer 0.8%, EO-PO block polyether 1.0%, maleic acid-acrylic acid copolymer sodium salt 0.2%; total amount 2.9%

[0220] Thickener: xanthan gum 0.95%, magnesium aluminum silicate 0.15%, carboxymethyl cellulose 1.05%; total amount 3.15%;

[0221] Antifreeze: ethylene glycol 3.1%, urea 0.2%; total amount 3.3%;

[0222] Suspension stabilizer: polyamide preparation 0.25%, EDTA 0.4%; total amount 0.65%;

[0223] The dosage of other technical materials and additives remains unchanged, and water is added to 100%.

[0224] The operation was the same as in Example 5. Due to the change in raw materials, only the suspension rate, wet sieve test, pourability, and sustained foam volume of the prepared product were tested. If any of these parameters failed, the product was deemed unqualified, and the remaining parameters were not tested. The test results of the prepared product are shown in Table 10.

[0225] Table 10 Test results of the thiodicarb aqueous suspension prepared

[0226]

[0227] As can be seen from the above analysis results, after strengthening the consumption of dispersant, thickening agent, antifreeze, suspension stabilizer four kinds of auxiliary agents, suspension rate, wet sieve test, lasting foam amount three indexes are qualified, and pourability is unqualified.The main reason that suspension rate can be qualified is: although the dispersant total amount reduces, because suspension stabilizer, thickening agent are compared with embodiment 5, feed ratio is larger, has maintained the good suspension performance of suspension.But because this material matching is compared with the material ratio screened under optimum conditions, matching is bad between the various auxiliary agents, and this index of pourability is still unqualified.

[0228] Comparative Example 7: Adjusting the types and amounts of various additives

[0229] 1. Measure the various raw materials according to the following material proportions.

[0230] Thiodicarb technical (discounted 100%) 30%

[0231] Dispersant: maleic acid-acrylic acid copolymer sodium salt 6.9%;

[0232] Thickener: xanthan gum 0.13%;

[0233] Antifreeze: ethylene glycol 4.3%;

[0234] Suspension stabilizer: polyamide preparation 0.4%;

[0235] Preservative and antifungal agent: sodium benzoate 0.25%;

[0236] Defoaming agent: silicone additive 0.8%;

[0237] pH adjuster: tartaric acid 0.05%.

[0238] Top up to 100% with water.

[0239] 2. Dissolve in water once

[0240] First, add 60% of the total amount of water to the dissolving kettle. Under stirring, add the measured xanthan gum, sodium benzoate, tartaric acid, and silicone additive in sequence. Observe the dissolution of the materials through the dissolving kettle sight glass. Once the materials are dissolved, set aside.

[0241] 3. Preparation

[0242] The measured technical, secondary water (the remaining 40% of the total water), dispersant sodium maleic acid-acrylic acid copolymer, ethylene glycol, and polyamide formulation are added to a mixing kettle for thorough mixing. The materials are continuously agitated by a special agitator within the mixing kettle, creating new interfaces and shearing, compressing, and folding the materials, thereby agitating and mixing them. Mixing is continued for 20 minutes. The primary water, which has already dissolved the materials, is then added from the dissolving kettle to the mixing kettle, and mixing is continued for 15 minutes. After the primary water is added and mixing is complete, the materials are fed into a high-shear emulsifier using gravity and the suction of a high-shear emulsifier. The strong shearing, dispersion, impact, and turbulence generated by the high-speed rotation of the rotor and stator cut the materials in the shear gaps, rapidly breaking them into micron-sized particles. The materials then enter the first and second sand milling stages of the high-shear emulsifier for 65 and 55 minutes, respectively. Each sand milling stage is inspected at each stage. The materials are then placed in a holding tank for storage, sampling, and analysis of various indicators. Due to the change in raw materials, only the suspension rate, wet sieve test, pourability, and sustained foam volume of the prepared product were tested. If any of these indicators failed, the product was deemed unqualified, and the remaining indicators were not tested. The test results of the prepared product are shown in Table 11.

[0243] Table 11 Test results of the prepared thiodicarb aqueous suspension

[0244]

[0245]

[0246] From the above analysis results, it can be seen that all additives were added in a single variety. Although the total amount of each variety added was within the set range, the product indicators were qualified, but the other three indicators of suspension rate, pourability, and persistent foam volume were all unqualified. The main reason is that: compared with the material ratio screened under the best conditions, a single quality was used in this material matching, and the matching between various additives was not good. The three indicators of suspension rate, pourability, and persistent foam volume were still unqualified.

[0247] Comparative Example 8

[0248] The operation is the same as that of Comparative Example 7, the only difference is the adjustment of the feeding amount, that is, the dispersant is adjusted from a single variety to four varieties, and the total amount remains unchanged; the types and addition amounts of other additives remain unchanged.

[0249] 1. Measure the various raw materials according to the following material proportions.

[0250] Thiodicarb technical (equivalent to 100%) 30% dispersant: sodium lauryl sulfate 1.9%, nonionic cosmetic copolymer 1.1%, EO-PO block polyether 2.3%, maleic acid-acrylic acid copolymer sodium salt 1.6%; total amount 6.9%;

[0251] Thickener: xanthan gum 0.13%;

[0252] Antifreeze: ethylene glycol 4.3%;

[0253] Suspension stabilizer: polyamide preparation 0.4%;

[0254] Preservative and antifungal agent: sodium benzoate 0.25%;

[0255] Defoaming agent: silicone additive 0.8%;

[0256] pH adjuster: tartaric acid 0.05%.

[0257] Top up to 100% with water.

[0258] 2. Dissolve in water once

[0259] First, add 60% of the total amount of water to the dissolving kettle. Under stirring, add the measured xanthan gum, sodium benzoate, tartaric acid, and silicone additive in sequence. Observe the dissolution of the materials through the dissolving kettle sight glass. Once the materials are dissolved, set aside.

[0260] 3. Preparation

[0261] The measured technical, secondary water (the remaining 40% of the total water), dispersant sodium maleic acid-acrylic acid copolymer, ethylene glycol, and polyamide formulation are added to a mixing kettle for thorough mixing. The materials are continuously agitated by a special agitator within the mixing kettle, creating new interfaces and shearing, compressing, and folding the materials, thereby agitating and mixing them. Mixing is continued for 20 minutes. The primary water, which has already dissolved the materials, is then added from the dissolving kettle to the mixing kettle, and mixing is continued for 15 minutes. After the primary water is added and mixing is complete, the materials are fed into a high-shear emulsifier using gravity and the suction of a high-shear emulsifier. The strong shearing, dispersion, impact, and turbulence generated by the high-speed rotation of the rotor and stator cut the materials in the shear gaps, rapidly breaking them into micron-sized particles. The materials then enter the first and second sand milling stages of the high-shear emulsifier for 65 and 55 minutes, respectively. Each sand milling stage is inspected at each stage. The materials are then placed in a holding tank for storage, sampling, and analysis of various indicators. Due to the change in raw materials, only the suspension rate, wet sieve test, pourability, and sustained foam volume of the prepared product were tested. If any of these indicators failed, the product was deemed unqualified, and the remaining indicators were not tested. The test results of the prepared product are shown in Table 12.

[0262] Table 12 Test results of the prepared thiodicarb aqueous suspension

[0263]

[0264] The above analysis shows that, with the exception of the dispersant, which was added in total and proportionately for each type, all other additives were added in single types. Although the total amount of each type of additive was within the specified range, the product's indicators, except for the suspension rate and wet sieving test, failed the pourability and persistent foam test. The main reason is that the dispersant is a key factor affecting the suspension rate and suspension stability. The total amount of dispersant added and the proportion of each type were within the optimal process parameters, so the suspension rate test passed. However, compared to the material matching ratios screened under optimal conditions, the use of a single quality resulted in poor matching between the various additives. Consequently, the pourability and persistent foam test still failed, resulting in a failed product.

[0265] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be encompassed within the scope of protection of the present invention.

Claims

1. A method for preparing a thiodicarb aqueous suspension concentrate, characterized in that: The components of the aqueous suspension concentrate, calculated by weight percentage, include 28.5-31.5% thiodicarb, 12.1-14.6% adjuvant, and the remainder is water; The auxiliary agent is composed of a dispersant, a thickener, an antifreeze agent, a suspension stabilizer, an antiseptic and mildew preventer, a defoamer and a pH regulator; The dispersant is a composite mixture of four surfactants: sodium lauryl sulfate, nonionic comb copolymer, EO-PO block polyether, and maleic acid-acrylic acid copolymer sodium salt; the nonionic comb copolymer is polynonylphenol polyoxyethylene ether, selected from polynonylphenol polyoxyethylene ether NP-4, polynonylphenol polyoxyethylene ether NP-7, polynonylphenol polyoxyethylene ether NP-9 or polynonylphenol polyoxyethylene ether NP-10; In the dispersant, the amount of sodium lauryl sulfate is 1.3-2.0%, the amount of nonionic comb copolymer is 0.9-1.5%, the amount of EO-PO block polyether is 0.9-2.3%, the amount of maleic acid-acrylic acid copolymer sodium salt is 0.8-1.6%, and the total amount of the four dispersant materials is 4.8-6.9%; The steps include: Step 1, ingredients: according to the material ratio, accurately measure the various material ingredients; Step 2, primary water dissolution: first add 60% of the total amount of water into the dissolution kettle, add one or two components of the suspension stabilizer, thickener, antiseptic and mildew inhibitor, pH regulator, defoamer and antifreeze after measurement at a time under stirring conditions, observe the dissolution of the material through the dissolution kettle sight glass, and set aside after the material is completely dissolved to form a primary mixed material; Step 3, secondary water dissolution: add the measured original drug thiodicarb, the remaining 40% of the total amount of water, and other additives into a mixing kettle and stir and mix. After fully mixing for 15-30 minutes, add the primary mixture in the dissolving kettle in step 2 into the dissolving kettle and continue stirring and mixing for 10-15 minutes to obtain the secondary mixture. Step 4, shearing: the secondary mixture obtained in step 3 is transferred to a high shear emulsifier and sheared and crushed into micron-sized particles; Step 5, sanding process; Step 6: Let it stand and take samples for analysis and inspection; Step 7: Packaging; The thickener is a mixture of xanthan gum, magnesium aluminum silicate and carboxymethyl cellulose; The antifreeze is a mixture of ethylene glycol and urea; The suspension stabilizer is a mixture of polyamide preparation and EDTA; The antiseptic and mildew preventer is a mixture of sodium benzoate and 1,2-benzisothiazolin-3-one; The defoaming agent is an organic silicon auxiliary agent, C8-C 10 mixtures of fatty alcohol compounds; The pH regulator is tartaric acid; The suspension stabilizer, thickener, preservative and mildew inhibitor, pH adjuster, defoamer and antifreeze added in step 2 are EDTA, xanthan gum, carboxymethyl cellulose, sodium benzoate, tartaric acid, organosilicon additive and urea respectively; In step 5, the first sand grinding process is: the particles obtained in step 4 are sand ground for 30-80 minutes using a horizontal sand mill, the speed of the horizontal sand mill is 1100 rpm, and the particle size of the sample after sand grinding is no more than 5 μm; and then the second sand grinding process is performed: the particles are sand ground for 20-60 minutes using a horizontal sand mill, the speed of the horizontal sand mill is 1440 rpm, and the particle size of the sample after sand grinding is no more than 3 μm.

2. The method for preparing a thiodicarb aqueous suspension concentrate according to claim 1, wherein In the thickener, the amount of xanthan gum is 0.01-1.0%, the amount of magnesium aluminum silicate is 0.2-1.2%, the amount of carboxymethyl cellulose is 0.01-1.0%, and the total amount of the three materials is 0.2-3%.

3. The method for preparing a thiodicarb aqueous suspension concentrate according to claim 1, wherein In the antifreeze, the amount of ethylene glycol is 3-5%, the amount of urea is 0.1-1.5%, and the total amount of the two materials is 3.5-5.5%; In the suspension stabilizer, the amount of polyamide preparation is 0.05-0.3%, the amount of EDTA is 0.05-0.5%, and the total amount of the two materials is 0.1-0.5%; In the antiseptic and mildew preventer, the dosage of sodium benzoate is 0.02-0.1%, the dosage of 1,2-benzisothiazolin-3-one is 0.08-0.15%, and the total dosage of the two materials is 0.08-0.2%; In the defoamer, the amount of the organosilicon additive is 0.2-0.8%, the amount of the C8-C10 fatty alcohol compound is 0.1-0.6%, and the total amount of the two materials is 0.3-0.9%; The dosage of tartaric acid as a pH adjuster is 0.05-0.1%; finally, water is added to make up to 100%.

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