Cationic Microcapsule Particles via Interfacial Polymerization
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Solution Overview
Problem
Existing microencapsulation methods fail to produce cationic microcapsules with low permeance and adherence to anionic surfaces, often requiring multiple layers or being commercially unattractive.
Innovation Solution
A method involving the reaction of an oil-phase composition with a water-phase composition using cationic or nonionic emulsifiers, resulting in microcapsules with a zeta potential of -5 millivolts or greater, enhancing adherence to anionic surfaces while maintaining low permeance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microencapsulation methods are used, then microcapsules can be formed, but they cannot achieve both low permeance and cationic charge for adherence to anionic surfaces
Solution Approach 1:
The patent changes the chemical parameters of the capsule wall by incorporating cationic surfactants (quaternary ammonium compounds) into the wall formulation. This modifies the surface charge from neutral or anionic to cationic, enabling electrostatic attraction to anionic surfaces while maintaining structural integrity and low permeance properties of the original wall material.
Solution Approach 2:
The patent creates a composite capsule wall structure by combining traditional wall-forming polymers (such as acrylic acid esters) with cationic surfactants. This composite approach allows the wall to simultaneously exhibit low permeance characteristics from the polymer matrix and cationic charge properties from the surfactant components, resolving the contradiction between structural performance and surface charge capability.
2Reliability
If multiple layers are added to achieve cationic charge and adherence, then surface interaction improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the wall-forming function and the surface charge function into a single integrated capsule wall structure. By incorporating cationic surfactants directly into the wall formulation during the encapsulation process, the patent eliminates the need for separate coating layers or post-treatment steps, thereby reducing manufacturing complexity while achieving the desired adherence performance.
3Reliability
If conventional encapsulation methods are used, then core material can be enclosed, but permeance is not sufficiently low for targeted release profiles
Solution Approach 1:
The patent modifies the physical and chemical parameters of the capsule wall by adjusting polymer concentration, molecular weight, and cross-linking density to achieve low permeance. The incorporation of cationic surfactants also affects the wall's packing density and intermolecular forces, further reducing permeance while enabling controlled release through electrostatic interactions with target surfaces.
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 method effectively produces microcapsules with strong adherence to anionic surfaces and low permeance, addressing the limitations of existing techniques by ensuring targeted release profiles and improved surface interaction.
Implementation Method 1
Interfacial polymerization is a process wherein a microcapsule wall of a polyamide, an epoxy resin, a polyurethane, a polyurea or the like is formed at an interface between two phases
Implementation Method 2
A method involving the reaction of an oil-phase composition with a water-phase composition using cationic or nonionic emulsifiers
Implementation Method 3
using cationic or nonionic emulsifiers, resulting in microcapsules
Implementation Method 4
microcapsules having a microcapsule wall of low permeance to the core material
Implementation Method 5
having a zeta potential of -5 millivolts or greater, the resulting microcapsules having strong adherence to anionic surfaces
Data Source
AI summary
The present invention teaches a cationically charged or neutral microcapsule particle comprising an oil soluble or dispersible core material and a wall material at least partially surrounding the core material, the microcapsule wall material comprising the reaction product of a first composition in the presence of a second composition comprising an emulsifier which is cationic or nonionic, the first composition comprising a reaction product of i) an oil soluble or dispersible amine with ii) a multifunctional acrylate or methacrylate monomer or oligomer, an oil soluble acid and an initiator. The cationic or nonionic emulsifier comprises a water soluble or water dispersible material and optionally a water phase initiator. The first composition initiator and the water phase initiator is an energy-activated initiator. The reaction product of the first composition and second composition results in the formation of a population of microcapsules having a microcapsule wall of low permeance to the core material and having a zeta potential of - 5 millivolts or greater. The resulting microcapsules have adherence to anionic surfaces.