Polyurea Microcapsule Zeta Potential and Composite Wall Design
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Solution Overview
Problem
Existing polyurea or polyurethane capsules face issues such as low olfactory intensity, low stability, high toxicity, and problematic deposition on target surfaces, making them unsuitable for applications like laundry, washing, and personal care where quick and efficient release is desired.
Innovation Solution
The development of microcapsule compositions comprising a first microcapsule with a zeta potential of 10 mV or greater and a second microcapsule with a zeta potential of 5 mV or less, along with specific encapsulating polymers and deposition aids, enhances the perceived olfactory intensity, stability, and deposition efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyurea or polyurethane capsules are used for encapsulation, then mechanical strength and ruggedness are improved, but olfactory intensity and stability deteriorate
Solution Approach 1:
The patent employs composite capsule wall materials comprising both polyurea and polyurethane components in specific ratios. This composite structure combines the mechanical strength advantages of polyurea with the stability benefits of polyurethane, resolving the contradiction between these two properties. The dual-polymer wall formulation allows simultaneous achievement of ruggedness and prolonged stability.
2Strength
If polyurea or polyurethane capsules are used for encapsulation, then mechanical strength is improved, but olfactory intensity deteriorates
Solution Approach 1:
The patent optimizes specific parameters including the ratio of polyurea to polyurethane in the capsule wall (controlled through stoichiometric ratios of isocyanate to amine/alcohol), molecular weights of starting materials, and crosslinking densities. These parameter adjustments fine-tune the balance between mechanical strength and olfactory intensity, allowing the capsule wall to be sufficiently strong while maintaining adequate fragrance release capability.
3Ease of manufacture
If conventional polycondensation processes are used, then capsule formation is achieved, but deposition on target surfaces deteriorates
Solution Approach 1:
The patent introduces deposition aids that selectively modify the surface properties of the capsule walls without affecting the bulk capsule formation process. These aids create localized changes in surface charge, hydrophobicity, or adhesion characteristics, enabling improved deposition on target surfaces while maintaining the simplicity of conventional polycondensation manufacturing.
4Ease of manufacture
If conventional polycondensation processes are used, then capsule formation is achieved, but toxicity increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the capsule wall by selecting specific isocyanates, amines, and alcohols with lower toxicity profiles. By adjusting the molecular structure and composition ratios of these starting materials, the patent achieves capsule formation through conventional polycondensation while reducing the toxicological impact of the final product.
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 proposed microcapsule compositions achieve high perceived olfactory intensity, prolonged stability, low toxicity, and improved deposition, making them suitable for various consumer applications such as personal care and fabric care products.
Implementation Method 1
the polycondensation reaction will take place. Thus, the small droplets of the water-immiscible phase will be surrounded by the capsule wall formed by polycondensation of the isocyanate and the polyalcohol or polyamine as starting materials
Implementation Method 2
Interfacial polycondensation is a known technique for preparing capsules and versatile capsule wall materials are used including polyureas and polyurethanes
Data Source
AI summary
A microcapsule composition useful in delivering an active material contains a first microcapsule and a second microcapsule. The first microcapsule has a zeta potential of 10 mV or greater, the second microcapsule has a zeta potential of 5 mV or less, and the weight ratio of the first microcapsule and the second microcapsule is between 1:10 and 10:1. Also disclosed are consumer products containing such a microcapsule composition.