CN101731210B - Process for preparing pesticide microcapsule by interfacial polymerization method - Google Patents

Abstract

The invention discloses a process for preparing pesticide microcapsules by interfacial polymerization. On the basis of the existing process, urea is used to replace polyamines and polyols in water-soluble monomers. The pesticide microcapsules prepared by the process of the present invention have a higher coating rate, the coating rate is above 98%, and the particle size of the microcapsules is 3-5um. It has the characteristics of water-based preparations and better exerts micro Sustained release of capsules: urea is used to replace polyamines and polyols, urea is directly dissolved in water to form an aqueous solution, and then isocyanate and pesticide active ingredients are dispersed in the aqueous solution to form an oil phase for interfacial polymerization. Compared with the traditional interfacial polymerization method: the urea material is easy to obtain, the price is low, and the production cost can be significantly reduced; the urea is directly dissolved in water to form an aqueous solution, which reduces the link of dropping, lower requirements for equipment, simpler operation, and convenient for industrialization Production, with strong market competitiveness.

Description

Preparation of Pesticide Microcapsules by Interfacial Polymerization

technical field

The invention relates to a new process for preparing pesticide microcapsules by using an improved method of interfacial polymerization.

Background technique

Pesticide microcapsules are a water-based preparation that can not only meet the requirements of strong safety, environmental protection and low price, but also prolong the duration of drug effect. Microcapsules refer to microcapsules that use natural or synthetic polymer capsule wall materials to coat solid, liquid or even gaseous microcapsule core substances to form semipermeable or closed capsules with a diameter of 1-800um. The required capsule wall material can form an adhesive film on the capsule core substance without chemical reaction with the capsule core substance. At the same time, the permeability, stability, hygroscopicity and other factors of the product should also be considered. Interfacial polymerization is the most commonly used method to prepare pesticide microcapsules. The process is briefly described as follows: Dissolve the active substance and a suitable monomer of the polymer capsule wall material in a water-immiscible organic solvent, and some low-viscosity crude oil does not require a solvent; then, the organic phase is sheared It can be added to the aqueous solution containing suitable emulsifiers and protective agents under certain conditions to form oil-in-water or water-in-oil. Control a certain particle size as required, and add another water-soluble capsule wall material into the water phase. The two materials react at the oil-water interface, forming a polymer capsule wall around the droplet containing the active substance. This method can generally be carried out quickly at room temperature, and the formed cyst wall is more regular, uniform, and hard in texture. The current commercialized pesticide microcapsules generally use highly reactive monomeric acid chlorides or isocyanates mixed with pesticide active ingredients as an oil phase to disperse in an aqueous solution, and add water-soluble monomeric polyamine and polyol solutions dropwise for interfacial polymerization. The disadvantages of the existing process for preparing pesticide microcapsules by interfacial polymerization are: high production cost, complex process, strict production process requirements, high equipment requirements, and not suitable for large-scale industrial production.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art and provide a process for preparing pesticide microcapsules by interfacial polymerization that is suitable for large-scale industrial production with low production cost, low equipment requirements, and simple process.

The solution of the present invention is: the technique for preparing pesticide microcapsules by interfacial polymerization, comprising the following process steps:

A. Dissolve the active ingredients of pesticides that are insoluble in water or have low solubility in water in organic solvents such as toluene and xylene to fully dissolve them to form an organic solution; if the active ingredients are oily, then directly enter step B;

B. Add an emulsifier that matches the active ingredients of the pesticide and stir evenly, then mix with toluene diisocyanate to form an organic phase;

C. Pour the organic phase into an aqueous solution dissolved with water-soluble monomers and polyvinyl alcohol as a dispersant, and shear it with a high-speed dispersing homogenizer to form a mixed solution;

D. Stir the mixed solution to fully react the isocyanate and the water-soluble monomer;

E. After adding thickener commonly used in the prior art, antifreezing agent and fully stirring, obtain the pesticide microcapsule water suspension;

It is characterized in that the water-soluble monomer is urea.

In the aqueous solution of the water-soluble monomer and polyvinyl alcohol, the concentration of urea as the water-soluble monomer is 1.0%-10%.

In the step D, when the mixture is stirred, it is heated in a constant temperature water bath, and the temperature range of the water bath heating is 10-50°C.

The pesticide microcapsules prepared by the process of the present invention have a higher coating rate, the coating rate is above 98%, and the particle size of the microcapsules is 3-5um. It has the characteristics of water-based preparations and better exerts micro Sustained release of capsules: urea is used to replace polyamines and polyols, urea is directly dissolved in water to form an aqueous solution, and then isocyanate and pesticide active ingredients are dispersed in the aqueous solution to form an oil phase for interfacial polymerization. Compared with the traditional interfacial polymerization method: urea material is easy to obtain and low in price, urea can replace polyamine and polyol can significantly reduce production cost; urea can be directly dissolved in water to form an aqueous solution, which reduces the steps of dripping and requires less equipment , the operation is simpler, it is convenient for industrial production, and it has strong market competitiveness.

Detailed ways

The following examples are only illustrative illustrations of the present invention, rather than limiting the scope of the present invention. The emulsifiers described in the following examples are different due to different dosage forms, and are known techniques in the technical field.

Example 1

Prepare 10% chlorfenapyr microcapsule suspension. Dissolve 10% chlorfenapyr in 16% toluene, add 8.4% emulsifier and 12% toluene-2.4-diisocyanate, stir well to form an organic phase, pour the organic phase into 4.2% urea and 1.0% disperse In the aqueous solution of polyvinyl alcohol 1988, in a high-speed shearing machine, shear at 20,000 rpm for 5 minutes, pour the shear liquid into the reaction kettle, stir and react for 10 hours under the condition of heating in a constant temperature water bath at 35°C, and then add 0.2% xanthan gum, 3.0% ethylene glycol, as a thickener and antifreeze, continue stirring for 2 hours to obtain 10% chlorfenapyr microcapsule suspension. The capsule suspension properties are as follows:

Appearance: Milky white aqueous suspension; Capsule shape: spherical; Average particle diameter: 2.14um; Decomposition rate (%): 1.44% when stored at 54±2°C for 14 days; Suspension rate: >90.0%.

Example 2

Prepare 30% phoxim microcapsule suspension. Add 9.5% emulsifier and 10% toluene-2.4-diisocyanate to 30% phoxim crude oil, stir evenly to form an organic phase, pour the organic phase into an aqueous solution of 4.1% urea and 1.0% dispersant polyvinyl alcohol 1988 In a high-speed shearing machine, shear at 20,000 rpm for 5 minutes, pour the shear liquid into the reaction kettle, and stir and react for 10 hours under the condition of heating in a constant temperature water bath at 35°C. Then add 0.3% xanthan gum and 7.0% ethylene glycol, and continue stirring for 2 hours to obtain 30% phoxim microcapsule suspension. The 30% phoxim microcapsule suspension has the following properties:

Appearance: Yellow aqueous suspension; Capsule shape: spherical; Average particle diameter: 2.8um; Decomposition rate (%): 1.35% when stored at 54±2°C for 14 days; Suspension rate: >90.0%.

Example 3

Prepare 5.0% beta-cypermethrin microcapsule suspension. Dissolve 5.0% beta-cypermethrin in 9.56% xylene, add 4.5% emulsifier and 4% toluene-2.4-diisocyanate, stir evenly to form an organic phase, pour the organic phase into 3.9% urea and 1.0% disperse In the aqueous solution of polyvinyl alcohol 1988, in a high-speed shearing machine, shear at 20,000 rpm for 5 minutes, pour the shearing liquid into the reaction kettle, and stir and react for 10 hours under the condition of heating in a constant temperature water bath at 35°C. Then add 0.25% xanthan gum and 4.0% ethylene glycol, and continue stirring for 2 hours to obtain 5.0% beta-cypermethrin microcapsule suspension. The properties of the 5.0% beta-cypermethrin microcapsule suspension are as follows:

Appearance: Milky white aqueous suspension; Capsule shape: spherical; Average particle diameter: 3.0um; Decomposition rate (%): 2.81% when stored at 54±2°C for 14 days. Suspension rate: >90.0%.

Example 4

Prepare 5.0% beta-cypermethrin microcapsule suspension. Add 6.8% emulsifier and 4% toluene-2.4-diisocyanate to 18.52% 27% beta-cypermethrin crude oil and stir evenly to form an organic phase, and pour the organic phase into 3.9% urea and 1.0% dispersant polyvinyl alcohol 1988 In the aqueous solution, shear at 20,000 rpm for 5 minutes in a high-speed shearing machine, pour the shearing liquid into the reaction kettle, and stir and react for 10 hours under the condition of heating in a constant temperature water bath at 35°C. Then add 0.2% xanthan gum and 3.0% ethylene glycol, and continue stirring for 2 hours to obtain 5.0% beta-cypermethrin capsule suspension. The properties of the 5.0% beta-cypermethrin capsule suspension are as follows:

Appearance: Milky white aqueous suspension; Capsule shape: spherical; Average particle diameter: 3.0um; Decomposition rate (%): 2.81% when stored at 54±2°C for 14 days; Suspension rate: >90.0%.

Example 5

Prepare 2.0% abamectin microcapsule suspension. 2.0% Abamectin former drug is dissolved in 16% chlorobenzene, adds 5.4% emulsifier and 3.6% toluene-2.4-diisocyanate, stirs to form an organic phase, the organic phase is poured into and is dissolved with 1.5% urea and 1.0 In the aqueous solution of % dispersant polyvinyl alcohol 1988, in a high-speed shearing machine, shear at 20,000 rpm for 5 minutes, pour the shear liquid into the reaction kettle, and stir and react for 10 hours under the condition of heating in a constant temperature water bath at 35°C. Then add 0.2% xanthan gum, 3.0% ethylene glycol, and continue to stir for 2 hours to obtain 2.0% abamectin microcapsule suspension. The 2.0% Abamectin Microcapsule Suspension Agent properties are as follows:

Appearance: Milky white aqueous suspension; Capsule shape: spherical; Average particle diameter: 3.0um; Decomposition rate (%): 1.44% when stored at 54±2°C for 14 days; Suspension rate: >90.0%.

Example 6

Prepare 10% pyridaben microcapsule suspension. Dissolve 10% pyridaben in 22% xylene, add 7.8% emulsifier and 6% toluene-2.4-diisocyanate, stir evenly to form an organic phase, pour the organic phase into 2.5% urea and 1.0% In the aqueous solution of dispersant polyvinyl alcohol 1988, in a high-speed shearing machine, shear at 20,000 rpm for 5 minutes, pour the shear liquid into the reaction kettle, and stir and react for 10 hours under the condition of heating in a constant temperature water bath at 35°C. Then add 0.3% xanthan gum and 5.0% ethylene glycol, and continue stirring for 2 hours to obtain 10% pyridaben microcapsule suspension. The 10% pyridaben microcapsule suspension has the following properties:

Appearance: Milky white aqueous suspension; Capsule shape: spherical; Average particle diameter: .4um; Decomposition rate (%): 2.0% when stored at 54±2°C for 14 days; Suspension rate: >90.0%.

Example 7

Prepare 10% trifluralin microcapsule suspension. Dissolve 10% trifluralin in 17.4% xylene, add 7.8% emulsifier and 5.6% toluene-2.4-diisocyanate, stir evenly to form an organic phase, pour the organic phase into a solution containing 2.5% urea and 1.0% In the aqueous solution of dispersant polyvinyl alcohol 1988, in a high-speed shearing machine, shear at 20,000 rpm for 5 minutes, pour the shear liquid into the reaction kettle, and stir and react for 10 hours under the condition of heating in a constant temperature water bath at 35°C. Then add 0.2% xanthan gum and 3.0% ethylene glycol, and continue stirring for 2 hours to obtain 10% trifluralin microcapsule suspension. The properties of the 10% trifluralin microcapsule suspension are as follows:

Appearance: Milky white aqueous suspension; Capsule shape: spherical; Average particle diameter: 2.8um; Decomposition rate (%): 2.5% when stored at 54±2°C for 14 days; Suspension rate: >90.0%.

Claims (2)

1. the technique of preparing pesticide microcapsules by interfacial polymerization method comprises following processing step:

A. pesticide active ingredient water insoluble or that solvability is lower in water being dissolved in makes it fully dissolve formation organic solution in toluene or the dimethylbenzene; If being grease, active ingredient then directly enters step B;

B. add the emulsifier for mixing that is complementary with pesticide active ingredient even, then mix forming organic facies with toluene di-isocyanate(TDI);

C. organic facies is poured into and be dissolved with in water-soluble monomer and the aqueous solution of polyvinyl alcohol as dispersant high speed dispersion homogenizer shearing formation mixed liquor;

D. mixed liquor is stirred, toluene di-isocyanate(TDI) and water-soluble monomer are fully reacted;

E. add after prior art commonly used thickener, antifreezing agent fully stir, namely get the pesticide micro capsule aqueous suspension agent;

It is characterized in that, described water-soluble monomer is urea, and in the aqueous solution of described water-soluble monomer and polyvinyl alcohol, urea is 1.0%--10% as the concentration of water-soluble monomer.

2. the technique of preparing pesticide microcapsules by interfacial polymerization method according to claim 1 is characterized in that, in described step D, when mixed liquor is stirred, carries out the water bath with thermostatic control heating, and its water bath heating temperature scope is 10-50 ℃.