According to the dosage form, pesticides can be classified into old emulsion (EC), Suspension Concentrate (SC), 3. Emulsion in water (EW) and microemulsion (ME), wettable powder. (WP), water-based (also known as water-based) dosage form and water-dispersible granule (WDG).
Agro-pharmaceutical is the process of processing a specific chemical or a mixture thereof that is usually biologically active into a product suitable for the desired environment and exerting optimal biological performance; adverse effects on the applicator and the environment and harm to crops To the lowest limit.
(1) Old-type emulsifiable concentrate (EC), emulsifiable concentrate is a commonly used pesticide formulation, which contains a large amount of organic solvents such as xylene, which wastes petroleum resources and causes environmental pollution, and is transported and stored due to the flammability of the solvent. And the choice of container is also limited.
(2) Suspension Concentrate (SC) is a solid drug that is insoluble or slightly soluble in water. It is uniformly dispersed in water by ultrafine pulverization by means of some auxiliaries to form a fine suspension with high particle size. Stable liquid solid state system. The suspending agent is usually composed of an active ingredient, a dispersing agent, a thickening agent, an anti-precipitating agent, an antifoaming agent, an antifreezing agent, and water. The content of the active ingredient is generally from 5% to 50%. The average particle size is generally about 3 μm. The dispersing agent has better dispersibility and spreadability, high suspending rate, strong adhesion to the surface of plant body, and resistance to rain erosion, so the efficacy is more significant than that of wettable powder. In the preparation of pesticide suspensions, it should be noted that: (1) the selected active ingredients are relatively stable to water, and the size of the original drug does not change during storage; (2) the viscosity of the preparation is suitable for low, and does not change with storage temperature. And change; (3) better naturally dispersed in water, and the diluent is relatively stable. Since the pesticide suspension agent is always present in the form of a concentrated suspension, chemical instability may occur during storage, especially for long-term storage, and in addition, physical stability problems are more often present. This usually involves three aspects: (1) flocculation and aggregation due to interaction between particles; (2) austenite crystal growth; (3) delamination and particle deposition due to gravity. To maintain the physical stability of the pesticide suspension during storage, it is necessary to control the accumulation, sedimentation and crystal growth of the suspension through formulation and processing.
(3) Emulsion in water (EW) and microemulsion (ME) have received much attention. Water emulsions (dense emulsions) and microemulsions are prepared by dispersing liquid or semi-solid pesticide active ingredients in water, and the active ingredients must be stable in water for a long time. Under intense agitation, the original drug is dispersed in water by means of a suitable emulsifier, and then a milky or transparent liquid prepared by adding an auxiliary agent such as a stabilizer or an antifreezing agent is a stable dispersion system. The difference between the water emulsion and the microemulsion is that the particle size of the active ingredient dispersed in water is different, the former is 0.1-50 μm, and the appearance is milky white; the latter particles are ultrafine, 0.01-0.1 μm, and the appearance is transparent or nearly transparent. The amount of emulsifier required to formulate a microemulsion is usually greater than the amount used to formulate an emulsifiable concentrate or water emulsion, sometimes up to 30%. Therefore, microemulsions are currently only suitable for high value-added crops such as fruit trees and vegetables.
Suspoemulsion (SE) is a stable high-suspension emulsion system which uses water as a dispersion medium by the action of various water-insoluble pesticide raw materials and crude oil. It consists of an opal phase and a continuous phase, both of which have one or more active ingredients, but the active ingredient in the continuous phase is in the form of a solid dispersion. Therefore, it has the advantages of suspending agent and water emulsion, avoids the poisoning of pesticides and wettable powders to operators by organic solvents and dusts, and environmental pollution, and is safer to store and transport, and has excellent performance and high biological activity. The efficacy is also relatively long lasting. The suspending agent will gradually replace the wettable powder and become the main dosage form of the pesticide, and drive the development of pesticide dosage forms such as suspending agent (SE), water emulsion (EW) and water dispersible granule (WDG).
(4) Wettable powder (WP)
(5) Aqueous (also known as water-based) dosage form and water-dispersible granules (WDG).
The pesticide aqueous formulation forms water as a dispersion medium, and the pesticide raw material (solid or oily liquid) is suspended or emulsified and dispersed in water by the action of a dispersing agent or an emulsifier and other auxiliary agents. Compared with emulsifiable concentrate, it reduces a large amount of organic solvent; compared with wettable powder, it has no dust scattering; it has low toxicity and irritation to humans and animals; it can reduce the phytotoxicity to crops; In the process of storage and transportation, it causes combustion and has high safety.
(6) Microcapsule pesticide
The microcapsule pesticide is a microcapsule preparation formed by coating an active substance such as a solid or a liquid pesticide in a capsule wall material by using a microcapsule technique. The so-called microcapsule technology uses a technique in which a dispersed solid, liquid or gas is coated with a natural or synthetic polymer film-forming material to form fine particles. The film-forming material is called wall material, and the coated material is called core material. The particle size of the microcapsules is generally 1-800 micrometers. The technology separates the object from the surrounding environment through a closed or semi-permeable wall film to protect and stabilize the core material, shield the odor or color, and control the release of the core material. These functions make microencapsulation an effective commercial method in many industrial fields.
The first to introduce microcapsule pesticides to the market is Pennwalt in the United States. Its first product was microencapsulated methyl parathion introduced in 1974. Since then, the sustained release technology has received extensive attention in the pesticide industry. Every year, an "International Symposium on Controlled Release of Pesticides" was held in the United States to summarize the exchange of research results. The company subsequently introduced microencapsulated diazinon, microencapsulated permethrin, herbicides DDT, pyrethrin, chlormequat, etc., which have been microencapsulated by various wall materials. More than 50 kinds of microcapsule pesticides were commercialized in 1994.
Agro-pharmaceutical is the process of processing a specific chemical or a mixture thereof that is usually biologically active into a product suitable for the desired environment and exerting optimal biological performance; adverse effects on the applicator and the environment and harm to crops To the lowest limit.
(1) Old-type emulsifiable concentrate (EC), emulsifiable concentrate is a commonly used pesticide formulation, which contains a large amount of organic solvents such as xylene, which wastes petroleum resources and causes environmental pollution, and is transported and stored due to the flammability of the solvent. And the choice of container is also limited.
(2) Suspension Concentrate (SC) is a solid drug that is insoluble or slightly soluble in water. It is uniformly dispersed in water by ultrafine pulverization by means of some auxiliaries to form a fine suspension with high particle size. Stable liquid solid state system. The suspending agent is usually composed of an active ingredient, a dispersing agent, a thickening agent, an anti-precipitating agent, an antifoaming agent, an antifreezing agent, and water. The content of the active ingredient is generally from 5% to 50%. The average particle size is generally about 3 μm. The dispersing agent has better dispersibility and spreadability, high suspending rate, strong adhesion to the surface of plant body, and resistance to rain erosion, so the efficacy is more significant than that of wettable powder. In the preparation of pesticide suspensions, it should be noted that: (1) the selected active ingredients are relatively stable to water, and the size of the original drug does not change during storage; (2) the viscosity of the preparation is suitable for low, and does not change with storage temperature. And change; (3) better naturally dispersed in water, and the diluent is relatively stable. Since the pesticide suspension agent is always present in the form of a concentrated suspension, chemical instability may occur during storage, especially for long-term storage, and in addition, physical stability problems are more often present. This usually involves three aspects: (1) flocculation and aggregation due to interaction between particles; (2) austenite crystal growth; (3) delamination and particle deposition due to gravity. To maintain the physical stability of the pesticide suspension during storage, it is necessary to control the accumulation, sedimentation and crystal growth of the suspension through formulation and processing.
(3) Emulsion in water (EW) and microemulsion (ME) have received much attention. Water emulsions (dense emulsions) and microemulsions are prepared by dispersing liquid or semi-solid pesticide active ingredients in water, and the active ingredients must be stable in water for a long time. Under intense agitation, the original drug is dispersed in water by means of a suitable emulsifier, and then a milky or transparent liquid prepared by adding an auxiliary agent such as a stabilizer or an antifreezing agent is a stable dispersion system. The difference between the water emulsion and the microemulsion is that the particle size of the active ingredient dispersed in water is different, the former is 0.1-50 μm, and the appearance is milky white; the latter particles are ultrafine, 0.01-0.1 μm, and the appearance is transparent or nearly transparent. The amount of emulsifier required to formulate a microemulsion is usually greater than the amount used to formulate an emulsifiable concentrate or water emulsion, sometimes up to 30%. Therefore, microemulsions are currently only suitable for high value-added crops such as fruit trees and vegetables.
Suspoemulsion (SE) is a stable high-suspension emulsion system which uses water as a dispersion medium by the action of various water-insoluble pesticide raw materials and crude oil. It consists of an opal phase and a continuous phase, both of which have one or more active ingredients, but the active ingredient in the continuous phase is in the form of a solid dispersion. Therefore, it has the advantages of suspending agent and water emulsion, avoids the poisoning of pesticides and wettable powders to operators by organic solvents and dusts, and environmental pollution, and is safer to store and transport, and has excellent performance and high biological activity. The efficacy is also relatively long lasting. The suspending agent will gradually replace the wettable powder and become the main dosage form of the pesticide, and drive the development of pesticide dosage forms such as suspending agent (SE), water emulsion (EW) and water dispersible granule (WDG).
(4) Wettable powder (WP)
(5) Aqueous (also known as water-based) dosage form and water-dispersible granules (WDG).
The pesticide aqueous formulation forms water as a dispersion medium, and the pesticide raw material (solid or oily liquid) is suspended or emulsified and dispersed in water by the action of a dispersing agent or an emulsifier and other auxiliary agents. Compared with emulsifiable concentrate, it reduces a large amount of organic solvent; compared with wettable powder, it has no dust scattering; it has low toxicity and irritation to humans and animals; it can reduce the phytotoxicity to crops; In the process of storage and transportation, it causes combustion and has high safety.
(6) Microcapsule pesticide
The microcapsule pesticide is a microcapsule preparation formed by coating an active substance such as a solid or a liquid pesticide in a capsule wall material by using a microcapsule technique. The so-called microcapsule technology uses a technique in which a dispersed solid, liquid or gas is coated with a natural or synthetic polymer film-forming material to form fine particles. The film-forming material is called wall material, and the coated material is called core material. The particle size of the microcapsules is generally 1-800 micrometers. The technology separates the object from the surrounding environment through a closed or semi-permeable wall film to protect and stabilize the core material, shield the odor or color, and control the release of the core material. These functions make microencapsulation an effective commercial method in many industrial fields.
The first to introduce microcapsule pesticides to the market is Pennwalt in the United States. Its first product was microencapsulated methyl parathion introduced in 1974. Since then, the sustained release technology has received extensive attention in the pesticide industry. Every year, an "International Symposium on Controlled Release of Pesticides" was held in the United States to summarize the exchange of research results. The company subsequently introduced microencapsulated diazinon, microencapsulated permethrin, herbicides DDT, pyrethrin, chlormequat, etc., which have been microencapsulated by various wall materials. More than 50 kinds of microcapsule pesticides were commercialized in 1994.
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