A high-suspension-rate thiophanate-methyl wettable powder and its preparation method

Abstract

This invention relates to a high-suspension-rate thiophanate-methyl wettable powder and its preparation method, belonging to the field of pesticide formulation technology. The wettable powder is composed of the following raw materials in parts by weight: 65-70 parts thiophanate-methyl, 3-6 parts carboxymethylated lignin complex, 0.5-2 parts wetting agent, 10-20 parts amino-modified kaolin, and 2-6 parts silica. The preparation method includes: mixing the carboxymethylated lignin complex, wetting agent, amino-modified kaolin, and silica to obtain a premix; adding thiophanate-methyl after air jet milling; and mixing again to obtain the final product. The wettable powder of this invention exhibits good wetting time and suspension rate, and excellent thermal storage stability.

Description

Technical Field

[0001] This invention belongs to the field of pesticide formulation technology, and relates to a high suspension rate thiophanate-methyl wettable powder and its preparation method. Background Technology

[0002] Thiophanate-Methyl is a broad-spectrum systemic fungicide with excellent control effects against fungal diseases in various crops, and is widely used in agricultural production in my country. Thiophanate-Methyl is almost insoluble in water and is usually prepared as a wettable powder. The wetting time and suspension rate of wettable powders are key indicators for evaluating product quality.

[0003] In existing technologies, thiophanate-methyl wettable powder is mainly formulated by compounding conventional dispersants such as lignin sulfonate and naphthalene sulfonate with fillers such as kaolin. For example, CN104351230A discloses a thiophanate-methyl wettable powder that uses sodium dodecyl sulfate as a dispersant; CN119924303A improves performance by modifying kaolin with β-cyclodextrin and synthesizing benzenesulfonate-based surfactants.

[0004] However, the existing technology still has the following technical problems: conventional dispersants have limited adsorption capacity for thiophanate-methyl, and desorption easily occurs after long-term storage, leading to a decrease in suspension rate; the mixing between dispersants and fillers is mostly a simple physical mixture, lacking synergistic design and failing to fully utilize the functions of each component. Therefore, developing new thiophanate-methyl wettable powders with good wetting and dispersibility and stability remains of significant practical importance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-suspension-rate thiophanate-methyl wettable powder and its preparation method, the product having the characteristics of fast wetting speed and high suspension rate.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a high-suspension-rate thiophanate-methyl wettable powder, which is composed of the following raw materials in parts by weight: Thiophanate-methyl 65-70 parts; 3-6 parts of carboxymethylated lignin complex; 0.5-2 parts wetting agent; 10-20 parts of amino-modified kaolin; 2-6 parts of silica; The carboxymethylated lignin complex comprises carboxymethylated lignin sulfonate and triethanolamine.

[0007] As used in this text, the term "carboxymethylated lignin complex" refers to a complex obtained by mixing carboxymethylated lignin sulfonate with triethanolamine. The carboxymethylated lignin sulfonate is obtained by reacting lignin sulfonate with chloroacetic acid under alkaline conditions, introducing a carboxymethyl hydrophilic group onto the lignin molecule. Triethanolamine binds to the carboxymethylated lignin sulfonate through hydrogen bonds and ionic bonds. This complex combines the drug-anchoring ability of carboxymethylated lignin sulfonate with the steric hindrance effect of triethanolamine. Furthermore, the alkalinity of triethanolamine can adjust the pH of the system, enhancing dispersion stability.

[0008] Preferably, the carboxymethylated lignin sulfonate is obtained by reacting lignin sulfonate with chloroacetic acid under alkaline conditions.

[0009] Includes the following steps: (a) Disperse lignin sulfonate in water, add sodium hydroxide to adjust the pH to 10-12, and activate for 30-60 minutes; (b) Add chloroacetic acid and react at 60-80°C for 2-4 hours; (c) Neutralize with acid to pH 7-8, dry, and pulverize to obtain.

[0010] During the preparation process, the phenolic and alcoholic hydroxyl groups on lignin undergo a nucleophilic substitution reaction with chloroacetic acid under alkaline conditions to generate carboxymethylated lignin sulfonate; then triethanolamine is added and mixed, and triethanolamine combines with carboxymethylated lignin sulfonate through hydrogen bonds to form a carboxymethylated lignin complex.

[0011] Preferably, the amino-modified kaolin is obtained by reacting kaolin with an aminosilane coupling agent.

[0012] More preferably, the aminosilane coupling agent is γ-aminopropyltriethoxysilane. γ-aminopropyltriethoxysilane molecules undergo a condensation reaction with the hydroxyl groups on the surface of kaolin, introducing the amino group onto the kaolin surface. During use with added water, the amino group is protonated and becomes positively charged, thereby generating electrostatic attraction with the negatively charged carboxymethylated lignin complex, forming a stable composite dispersion system.

[0013] Preferably, the wetting agent is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and fatty alcohol polyoxyethylene ether.

[0014] Preferably, it also contains 0.2-0.8 parts of sodium polyacrylate.

[0015] Preferably, the mass ratio of the carboxymethylated lignin complex to the amino-modified kaolin is 1:3-1:4. During use with water, the negative charge provided by the carboxymethylated lignin complex and the positive charge provided by the amino-modified kaolin reach a dynamic balance, which ensures both appropriate electrostatic attraction between particles and that the overall structure maintains a negative charge, thus avoiding flocculation and precipitation caused by excessive charge neutralization.

[0016] Secondly, the present invention provides a method for preparing a high-suspension-rate thiophanate-methyl wettable powder, comprising the following steps: (1) Mix carboxymethylated lignin complex, wetting agent, amino-modified kaolin, and silica evenly to obtain a premix; (2) The technical grade thiophanate-methyl is subjected to air jet milling; (3) Mix the premixed material from step (1) with the pulverized raw material from step (2) for 20-40 minutes to obtain high suspension rate thiophanate-methyl wettable powder.

[0017] Preferably, the pressure of the air jet milling is 0.5-0.6 MPa.

[0018] The beneficial effects of this invention are: (1) The carboxymethylated lignin complex has a strong adsorption capacity for thiophanate-methyl; the long-chain alcohol structure of triethanolamine extends in water to form a steric hindrance layer, preventing particle aggregation and improving suspension rate. The surface of the carboxymethylated lignin complex is rich in carboxymethyl hydrophilic groups, which have good hydrophilicity. Combined with the wetting agent added to the formula, the wettable powder is quickly wetted and dispersed after entering the water.

[0019] (2) An electrostatic synergistic effect is formed between amino-modified kaolin and carboxymethylated lignin complex, which further improves the stability of the formulation; silica forms an anti-caking system and enhances storage stability. Detailed Implementation

[0020] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the embodiments, is provided below.

[0021] Example 1 A method for preparing a high-suspension-rate thiophanate-methyl wettable powder includes the following steps: Raw materials: 68 parts methyl thiophanate, 4.5 parts carboxymethylated lignin complex, 1 part sodium dodecyl sulfate, 16 parts amino-modified kaolin, and 4 parts silica.

[0022] (1) Mix carboxymethylated lignin complex, wetting agent, amino-modified kaolin, and silica evenly to obtain a premix; (2) Methylthiophanate was subjected to air jet milling, with the milling pressure controlled at 0.50 MPa, and milled to a particle size D90≤18μm; (3) Mix the premix from step (1) with the pulverized thiophanate-methyl from step (2) for 30 minutes to obtain thiophanate-methyl wettable powder with high suspension rate.

[0023] Preparation of carboxymethylated lignin complex: 100g of lignin sulfonate was dispersed in 1000mL of water, and sodium hydroxide was added to adjust the pH to 11. The mixture was activated at 70℃ for 40 minutes. 80g of chloroacetic acid was added, and the reaction was carried out at 70℃ for 3 hours. The mixture was neutralized with hydrochloric acid to pH 7.0, dried, and pulverized to obtain carboxymethylated lignin sulfonate. 10g of triethanolamine was added, and the mixture was stirred at room temperature for 30 minutes. The mixture was then pulverized to obtain the carboxymethylated lignin complex.

[0024] Preparation of amino-modified kaolin: 200g of kaolin was dispersed in 1000mL of ethanol-water solution (ethanol:water = 8:2), and 20g of γ-aminopropyltriethoxysilane was added. The mixture was reacted at 70℃ for 3 hours. After filtration, washing with ethanol, drying, and pulverizing, amino-modified kaolin was obtained.

[0025] Example 2 A method for preparing a high-suspension-rate thiophanate-methyl wettable powder includes the following steps: Raw materials: 65 parts thiophanate-methyl, 3 parts carboxymethylated lignin complex, 0.5 parts AEO-7, 10 parts amino-modified kaolin, and 3 parts silica.

[0026] (1) Mix carboxymethylated lignin complex, AEO-7, amino-modified kaolin, and silica evenly to obtain a premix; (2) Methylthiophanate was subjected to air jet milling, with the milling pressure controlled at 0.60 MPa, and milled to a particle size D90≤15μm; (3) Mix the premix from step (1) with the pulverized thiophanate-methyl from step (2) for 30 minutes to obtain the final product.

[0027] Example 3 A method for preparing a high-suspension-rate thiophanate-methyl wettable powder includes the following steps: Raw materials: 70 parts thiophanate-methyl, 6 parts carboxymethylated lignin complex, 2 parts sodium dodecyl sulfate, 20 parts amino-modified kaolin, 6 parts silica, and 0.5 parts sodium polyacrylate.

[0028] (1) Mix carboxymethylated lignin complex, sodium dodecyl sulfate, amino-modified kaolin, silica, and sodium polyacrylate evenly to obtain a premix; (2) Thiophanate-methyl is subjected to air jet milling, with the milling pressure controlled at 0.55 MPa, and milled to a particle size D90≤18μm; (3) Mix the premix from step (1) with the pulverized thiophanate-methyl from step (2) for 40 minutes to obtain the final product.

[0029] Example 4 A method for preparing a high-suspension-rate thiophanate-methyl wettable powder includes the following steps: Raw materials: 67 parts thiophanate-methyl, 4 parts carboxymethylated lignin complex, 0.5 parts sodium dodecylbenzenesulfonate, 15 parts amino-modified kaolin, and 2 parts silica.

[0030] (1) Mix carboxymethylated lignin complex, sodium dodecylbenzene sulfonate, amino-modified kaolin, and silica evenly to obtain a premix; (2) Methylthiophanate was subjected to air jet milling, with the milling pressure controlled at 0.60 MPa, and milled to a particle size D90≤15μm; (3) Mix the premix from step (1) with the pulverized thiophanate-methyl from step (2) for 25 minutes to obtain the final product.

[0031] Comparative Example 1 Compared with Example 1, the difference is that the carboxymethylated lignin complex is replaced with an equal amount of carboxymethylated lignin sulfonate (without triethanolamine), and the rest is the same as in Example 1.

[0032] Comparative Example 2 Compared with Example 1, the difference is that the amino-modified kaolin is replaced with an equal amount of ordinary kaolin, and the rest is the same as in Example 1.

[0033] Comparative Example 3 The carboxymethylated lignin complex in Example 1 was replaced with an equal amount of unmodified lignin and triethanolamine mixture, and the rest was the same as in Example 1.

[0034] Performance testing: The examples and comparative examples were tested according to the methods specified in GB / T 23552-2009.

[0035] Wetting time: Weigh 5g of sample and pour it from a specified height into a beaker containing 100mL of distilled water. Record the time it takes for the sample to be completely wetted.

[0036] Suspension rate: Weigh 2.5g of sample, prepare a suspension with standard hard water, let stand at 30℃ for 30 minutes, extract the upper 9 / 10 of the suspension, determine the content of effective ingredients in the bottom precipitate, and calculate the suspension rate.

[0037] Thermal storage stability test: After sealing the sample, store it in a constant temperature chamber at 54℃ for 14 days. After taking it out, cool it to room temperature and measure the suspension rate according to the above method. Calculate the change in suspension rate before and after storage.

[0038]

[0039] This invention utilizes multiple technical means, such as carboxymethylation modification and amino-modified kaolin, to shorten the wetting time of the product to less than 60 seconds, achieve a suspension rate of over 96%, demonstrate excellent thermal storage stability, and exhibit significantly superior overall performance compared to the comparative example.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-suspension-rate thiophanate-methyl wettable powder, characterized in that, It consists of the following raw materials in parts by weight: Thiophanate-methyl 65-70 parts; 3-6 parts of carboxymethylated lignin complex; 0.5-2 parts wetting agent; 10-20 parts of amino-modified kaolin; 2-6 parts of silica; The carboxymethylated lignin complex comprises carboxymethylated lignin sulfonate and triethanolamine.

2. The high suspension rate thiophanate-methyl wettable powder according to claim 1, characterized in that, The carboxymethylated lignin sulfonate is obtained by reacting lignin sulfonate with chloroacetic acid under alkaline conditions.

3. The high suspension rate thiophanate-methyl wettable powder according to claim 1, characterized in that, The amino-modified kaolin is obtained by reacting kaolin with an aminosilane coupling agent.

4. The high suspension rate thiophanate-methyl wettable powder according to claim 3, characterized in that, The aminosilane coupling agent is γ-aminopropyltriethoxysilane.

5. The high suspension rate thiophanate-methyl wettable powder according to claim 2, characterized in that, The preparation method of the carboxymethylated lignin sulfonate includes the following steps: (a) Disperse lignin sulfonate in water, add sodium hydroxide to adjust the pH to 10-12, and activate for 30-60 minutes; (b) Add chloroacetic acid and react at 60-80°C for 2-4 hours; (c) Neutralize with acid to pH 7-8, dry, and pulverize to obtain.

6. The high suspension rate thiophanate-methyl wettable powder according to claim 1, characterized in that, The wetting agent is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and fatty alcohol polyoxyethylene ether.

7. The high suspension rate thiophanate-methyl wettable powder according to claim 1, characterized in that, It also contains 0.2-0.8 parts of sodium polyacrylate.

8. The high suspension rate thiophanate-methyl wettable powder according to claim 1, characterized in that, The mass ratio of the carboxymethylated lignin complex to the amino-modified kaolin is 1:3-1:

4.

9. A method for preparing the high suspension rate thiophanate-methyl wettable powder as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Mix carboxymethylated lignin complex, wetting agent, amino-modified kaolin, and silica evenly to obtain a premix; (2) The technical grade thiophanate-methyl is subjected to air jet milling; (3) Mix the premixed material from step (1) with the pulverized raw material from step (2) for 20-40 minutes to obtain high suspension rate thiophanate-methyl wettable powder.

10. The preparation method according to claim 9, characterized in that, The pressure of the airflow pulverizer is 0.5-0.6 MPa.

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