Polyurea Microcapsule Wall Composition for Lambda-Cyhalothrin
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Solution Overview
Problem
Existing microencapsulation technologies for lambda-cyhalothrin face challenges in balancing worker safety and pest control efficacy, as previously described polyurea walls do not meet the desired properties for improved toxicology profiles and rapid release in agricultural settings.
Innovation Solution
A microcapsule composition with a polyurea wall made from a specific mixture of polymethylene polyphenylisocyanate and isomeric toluene diisocyanate, encapsulating lambda-cyhalothrin and titanium dioxide particles, with controlled particle sizes and weight ratios, to enhance worker safety while maintaining effective pest control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polyurea wall is made from a specific mixture of isocyanates to improve worker safety and toxicology profile, then worker exposure characteristics are improved, but the release rate of lambda-cyhalothrin may be reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio of polymethylene polyphenylisocyanate to toluene diisocyanate (80:20) in the polyurea wall formulation, and by controlling wall content at 7-8% and microcapsule size at 1-4 microns, to achieve both improved worker safety and maintained release rate
Solution Approach 2:
The patent uses a composite polyurea wall structure formed from a specific mixture of two different isocyanates (polymethylene polyphenylisocyanate and toluene diisocyanate in 80:20 ratio), creating a material with optimized properties that balance protection and release characteristics
2Object-affected harmful factors
If the polyurea wall content is increased to improve worker safety, then toxicology profile is improved, but the microcapsule size and release characteristics may be affected
Solution Approach 1:
The patent optimizes the wall content parameter to a specific range of 7-8% by weight, which is sufficient to provide improved worker protection and toxicology profile while maintaining microcapsule size within the desired 1-4 micron range and preserving release characteristics
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides improved toxicology profiles and rapid release of lambda-cyhalothrin, ensuring better safety for workers and effective pest control, with the microcapsules being suitable for foliar application and other agricultural uses.
Implementation Method 1
hydrolysis of an isocyanate monomer to form an amine via a carbamic acid intermediate occurs, and that in turn reacts with another isocyanate monomer to form the polyurea
Implementation Method 2
hydrolysis of an isocyanate monomer to form an amine via a carbamic acid intermediate occurs
Implementation Method 3
dispersed titanium dioxide particles
Implementation Method 4
dispersed titanium dioxide particles
Data Source
AI summary
A composition comprising a microcapsule having a polyurea wall encapsulating a pyrethroid insecticide, wherein the polyurea wall of the microcapsule is made of polyurea polymers derived from a mixture of aromatic polyisocyanate (A) and aromatic diisocyanate (B), the weight ratio of (A) to (B) is 1:1, the polymer (or wall) content of each microcapsule is from 6 to 9 % by weight, and the amount of the pyrethroid insecticide is from 15 to 60 % by weight, each based on the weight of the microcapsule; such a composition providing improved worker exposure characteristics.