RU2488437C1 - Method of producing microcapsules of pesticides by nonsolvent precipitation method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to microencapsulation, particularly microencapsulation of pesticides. The method consists in physical-chemical precipitation using two precipitants - butanol and ethanol. The microcapsule cladding is sodium carboxymethyl cellulose.

EFFECT: invention increases mass output of microcapsules while simplifying the process of producing microcapsules.

7 ex

Description

The invention relates to the field of microencapsulation of pesticides.

Previously known methods for producing microcapsules of pesticides. So, in US Pat. 2108036 Russian Federation IPC A01N 25/28, A01N 37/22, published April 10, 1998, describes a method for producing a microencapsulated herbicidal composition comprising acetochlor as an active ingredient and an acceptable antidote for it, enclosed in microcapsules obtained by dispersing the active ingredient at room temperature, and mixtures of polymethylene polyphenyl isocyanate and isomeric 2,4- and 2,6-tolylenediisocyanates, taken in the ratio of 1.5-2: 1, in the aqueous phase containing 1.0-1.5 wt.% protective colloid, mainly alkaline metal lignosulfonate,0.3-1.0 wt.% Surfactant, followed by heating the mixture to 40-90 ° C and cooled to room temperature.

The disadvantages of the proposed method are dispersion in the aqueous phase, which complicates the process of obtaining microcapsules of drugs in polymers that form jellies in an aqueous medium at low concentrations in solution.

In US Pat. 2089062 Russian Federation IPC A01N 25/28, published 09/10/1997, a method for producing microencapsulated pesticides according to the invention is described, based on the known microencapsulation method consisting of interfacial polycondensation of polymethylene polyphenyl isocyanate and polyamine in the presence of a pesticidally active substance in an aqueous medium containing that as a surfactant use the ammonium salt of a partial ester of a copolymer of styrene and maleic anhydride (1: 1) in an amount of 2-8 wt.% of the amount of pesticidal active substance. As pesticides, it is preferable to use metolachlorprofenfos, propiconazole, diazinon.

The disadvantages of the invention are the production of microcapsules by the chemical method of interfacial polymerization, which consists of several stages, which makes the process lengthy and complicates it, the use as a surfactant of the composition of the ammonium salt of a partial ester of a copolymer of styrene and maleic aldehyde in a certain ratio, which can be replaced by one compound, for example, OS- twenty.

In US Pat. 2159037 Russian Federation IPC A01N 25/28, A01N 25/30, published 11/20/2000, describes microcapsules obtained by a polymerization reaction at the phase boundary, containing solid agrochemical material 0.1-55 wt.% Suspended in an organic liquid mixed with water , 0.01-10 wt.% Non-ionic dispersant, active at the phase boundary and not acting as an emulsifier. The microcapsule may contain a herbicide as an agrochemical agent and organic liquid. As a polymer wall, the microcapsules contain a polymer based on a mixture of isocyanates or an esterified urea-formaldehyde fluoropolymer. A method of producing microcapsules consists in obtaining a suspension of an agrochemical agent in an organic liquid containing the indicated dispersant and fluoropolymers and introducing the resulting suspension into an aqueous phase containing a protective colloid and a surfactant, followed by stirring the mixture at high shear and adjusting the temperature and / or pH if necessary emulsions to form microcapsules.

The disadvantages of the proposed method are the complexity of the methodology due to the production of microcapsules by a method that includes several stages, the use of special equipment (high shear mixer), the duration of the process.

In US Pat. WO / 2010/137743 JP IPC A01N 25/28; A01N 51/00; A01P 7/04; B01J 13/16, published December 2, 2010, describes a method for producing microcapsules containing pesticidal compounds in a fatty acid ester, which delays the release of pesticidal compounds compared to conventional microcapsules. The method of obtaining microcapsules includes:

1) maintaining the mixture of the pesticidal compound with the polyisocyanate from 20 to 60 ° C for 3 hours or more;

2) adding to the mixture water containing polyols or polyamines, as well as preparing the formation of liquid drops in water;

3) the formation of a film of polyurethane or polyurea around the drops.

The disadvantages of the proposed method are the use of special equipment (rotary homogenizer), multi-stage, which complicates the method of obtaining microcapsules and makes it long.

The closest method is the method proposed in US Pat. 2165700 Russian Federation IPC A01N 25/28, A01N 53/00, A01N 57/00, published 04/27/2001, describes a method for producing microencapsulated insecticidal preparations, which consists in the following: solution of a mixture in an organic solvent consisting of natural lipids and organophosphorus and / or a pyrethroid insecticide in a weight ratio of 2-4: 1, dispersed in water to obtain the target product. Using the proposed method can significantly simplify the process of encapsulation of insecticides and provides high quality insecticidal preparation.

The disadvantage of the method proposed in US Pat. 2165700, is dispersion in an aqueous medium, which makes the proposed method not applicable for the preparation of microcapsules of water-soluble preparations in water-soluble polymers.

The technical task is to simplify the process of obtaining microcapsules of the drug in water-soluble polymers, increasing the yield by weight.

The solution of the technical problem is achieved by the method of producing microcapsules, characterized in that when receiving the microcapsules by the physicochemical precipitation method with a non-solvent, butanol and ethanol are used as precipitators, and sodium carboxymethyl cellulose is used as the shell of the microcapsules, the production process is carried out without special equipment.

A distinctive feature of the proposed method is the use of two precipitants - butanol and ethanol in the preparation of microcapsules by the physicochemical method of precipitation with a non-solvent and sodium carboxymethyl cellulose as a shell of microcapsules.

The result of the proposed method is to obtain microcapsules of pesticides at 25 ° C for 15 minutes.

The sodium carboxymethyl cellulose needed for the reaction was industrial production.

EXAMPLE 1. Obtaining microcapsules metolachlor in sodium carboxymethyl cellulose, the ratio of 1: 3

To 6 g of a 5% solution of sodium carboxymethyl cellulose in butanol add 0.01 g of the preparation E472c as a surfactant. The resulting mixture is placed on a magnetic stirrer and include stirring. 0.1 g of metolachlor is dissolved in 0.5 ml of DMSO and transferred to a solution of sodium carboxymethyl cellulose in butanol. After the formation of an independent solid phase by metolachlor, 3 ml of ethanol and 1 ml of distilled water are slowly added dropwise. The resulting suspension of microcapsules is filtered on a 16-class pore filter, washed with acetone, dried in a desiccator over calcium chloride.

Received 0.230 g of microcapsules. The yield was 58%.

EXAMPLE 2. Obtaining microcapsules of propiconazole + trebuconazole in sodium carboxymethyl cellulose, the ratio of 1: 3

To 6 g of a 5% solution of sodium carboxymethyl cellulose in butanol add 0.01 g of the preparation E472c as a surfactant. The resulting mixture is placed on a magnetic stirrer and include stirring. 0.1 g of propiconazole + trebuconazole is dissolved in 0.5 ml of DMSO and transferred to a solution of sodium carboxymethyl cellulose in butanol. After the formation of an independent solid phase with propiconazole + trebuconazole, 3 ml of ethanol and 1 ml of distilled water are slowly added dropwise. The resulting suspension of microcapsules is filtered on a 16-class pore filter, washed with acetone, dried in a desiccator over calcium chloride.

Received 0.230 g of microcapsules. The yield was 58%.

EXAMPLE 3. Obtaining microcapsules of clopyralide in sodium carboxymethyl cellulose, ratio 1: 3

To 6 g of a 5% solution of sodium carboxymethyl cellulose in butanol add 0.01 g of the preparation E472c as a surfactant. The resulting mixture is placed on a magnetic stirrer and include stirring. 0.1 g of clopyralid is dissolved in 0.5 ml of DMSO and transferred to a solution of sodium carboxymethyl cellulose in butanol. After clopyralid formation of an independent solid phase, 3 ml of ethanol and 1 ml of distilled water are added very slowly dropwise. The resulting suspension of microcapsules is filtered on a 16-class pore filter, washed with acetone, dried in a desiccator over calcium chloride.

Received 0.235 g of microcapsules. The yield was 59%.

EXAMPLE 4. Obtaining microcapsules trebicide in sodium carboxymethyl cellulose, the ratio of 1: 3

To 6 g of a 5% solution of sodium carboxymethyl cellulose in butanol add 0.01 g of the preparation E472c as a surfactant. The resulting mixture is placed on a magnetic stirrer and include stirring. 0.1 g of trebicide is dissolved in 0.5 ml of DMSO and transferred to a solution of sodium carboxymethyl cellulose in butanol. After the formation of an independent solid phase by trebicide, 3 ml of ethanol and 1 ml of distilled water are slowly added dropwise. The resulting suspension of microcapsules is filtered on a 16-class pore filter, washed with acetone, dried in a desiccator over calcium chloride.

Received 0.235 g of microcapsules. The yield was 59%.

EXAMPLE 5. Obtaining microcapsules of haloxifop-p-methyl in sodium carboxymethyl cellulose, ratio 1: 3

To 6 g of a 5% solution of sodium carboxymethyl cellulose in butanol add 0.01 g of the preparation E472c as a surfactant. The resulting mixture is placed on a magnetic stirrer and include stirring. 0.1 g of haloxyphop-p-methyl is dissolved in 0.5 ml of DMSO and transferred to a solution of sodium carboxymethyl cellulose in butanol. After haloxifopom-p-methyl formation of an independent solid phase, 3 ml of ethanol and 1 ml of distilled water are added very slowly dropwise. The resulting suspension of microcapsules is filtered on a 16-class pore filter, washed with acetone, dried in a desiccator over calcium chloride.

Received 0.255 g of microcapsules. The yield was 64%.

EXAMPLE 6. Obtaining microcapsules of fenoxaprop-p-ethyl in sodium carboxymethyl cellulose, the ratio of 1: 3

To 6 g of a 5% solution of sodium carboxymethyl cellulose in butanol add 0.01 g of the preparation E472c as a surfactant. The resulting mixture is placed on a magnetic stirrer and include stirring. 0.1 g of fenoxaprop-p-ethyl is dissolved in 0.5 ml of DMSO and transferred to a solution of sodium carboxymethyl cellulose in butanol. After phenoxaprop-p-ethyl formed an independent solid phase, 3 ml of ethanol and 1 ml of distilled water are slowly added dropwise. The resulting suspension of microcapsules is filtered on a 16-class pore filter, washed with acetone, dried in a desiccator over calcium chloride.

Received 0.245 g of microcapsules. The yield was 61%.

EXAMPLE 7. Obtaining microcapsules of celodime in sodium carboxymethyl cellulose, ratio 1: 3

To 6 g of a 5% solution of sodium carboxymethyl cellulose in butanol add 0.01 g of the preparation E472c as a surfactant. The resulting mixture is placed on a magnetic stirrer and include stirring. 0.1 g of celodime is dissolved in 0.5 ml of DMSO and transferred to a solution of sodium carboxymethyl cellulose in butanol. After the formation of an independent solid phase by the kladodyme, 3 ml of ethanol and 1 ml of distilled water are added dropwise very slowly. The resulting suspension of microcapsules is filtered on a 16-class pore filter, washed with acetone, dried in a desiccator over calcium chloride.

Received 0.235 g of microcapsules. The yield was 59%.

Thus, microcapsules were obtained by physicochemical precipitation with a non-solvent using butanol and ethanol as precipitants, which contributes to an increase in yield. The process is simple to execute and lasts for 15 minutes, does not require special equipment.

The proposed technique is suitable for the agricultural industry due to ease of execution and manufacturability.

Claims (1)

A method of producing microcapsules of pesticides by non-solvent precipitation method, characterized in that when receiving microcapsules by the physicochemical non-solvent precipitation method, butanol and ethanol are used as precipitators, and sodium carboxymethyl cellulose is used as a shell of microcapsules, the production process is carried out without special equipment.