Paraquat Emulsion Composition for Stable Multi-Herbicide Formulations
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Solution Overview
Problem
Formulating paraquat with other herbicides like butafenacil and S-metolachlor is challenging due to paraquat's high ionic strength, leading to formulation complications and surfactant incompatibility, and existing emulsifier systems fail to create stable emulsions.
Innovation Solution
A stable emulsion is achieved using an emulsifier package comprising a polyvinylalcohol-acetate copolymer, sorbitan ester surfactant, and polymeric ethoxylated sorbitan ester, which dissolves paraquat and maintains stability even with additional pesticidal active ingredients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If paraquat is formulated with additional herbicides using conventional emulsifier systems, then the formulation complexity increases, but the emulsion stability deteriorates due to surfactant incompatibility caused by paraquat's high ionic strength
Solution Approach 1:
The patent employs a composite emulsifier system comprising multiple components (polyvinyl alcohol, sorbitan esters, and ethoxylated sorbitan esters) that work synergistically to stabilize the emulsion. This composite approach allows the formulation to accommodate paraquat's high ionic strength while maintaining emulsion stability and enabling the inclusion of additional herbicides like butafenacil and S-metolachlor
Solution Approach 2:
The polyvinyl alcohol acts as an intermediary substance that mediates between the charged paraquat molecules and the oil phase containing additional herbicides. This intermediary component facilitates compatibility among ingredients that would otherwise be incompatible due to electrostatic repulsion and surfactant interference
2Device complexity
If polyvinyl alcohol is used as an emulsifier with highly charged active ingredients like glyphosate and gluphosinate, then the formulation simplicity is maintained, but the polyvinyl alcohol precipitates out of solution
Solution Approach 1:
The patent modifies the chemical parameters of the emulsifier system by selecting specific types of sorbitan esters and ethoxylated sorbitan esters that are compatible with polyvinyl alcohol in the presence of paraquat. This parameter optimization allows polyvinyl alcohol to remain soluble and functional with highly charged active ingredients, preventing precipitation while maintaining formulation simplicity
3Reliability
If a stable emulsion is achieved with paraquat and additional herbicides, then the pesticidal efficacy is enhanced, but the formulation development time increases due to surfactant compatibility challenges
Solution Approach 1:
The patent applies preliminary action by pre-selecting and optimizing the emulsifier package composition before final formulation development. The identified combination of polyvinyl alcohol, sorbitan esters, and ethoxylated sorbitan esters is pre-tested for compatibility with paraquat and additional herbicides, establishing a reliable base formulation that reduces subsequent development time and accelerates product deployment
Data Source
AI summary
The present invention relates to pesticidal emulsions comprising an aqueous continuous phase comprising paraquat and at least one polyvinylalcohol or polyvinylalcohol derivative; a dispersed oil phase; a pesticidal active ingredient; and at least two polymeric surfactants selected from a sorbitan ester and an ethoxylated sorbitan ester. It also relates to the use of a pesticidal emulsion to control undesired vegetation.